1. |
- Axenrot, Thomas, et al.
(author)
-
Behovsanalys och förslag på övervakning av fisk och kräfta : Underlag för beståndsbedömningar i Hjälmaren, Mälaren, Vänern och Vättern
- 2024
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Reports (other academic/artistic)abstract
- Under 2021-2023 hade SLU Aqua ett uppdrag från HaV att utvärdera den data som finns för fisk och kräftor i Sveriges stora sjöar. Projekten Miljöövervakning stora sjöarna och Bestånds- och ekosystemanalys i stora sjöar lyfter fram datainsamlingen utifrån olika syften och olika sätt.Denna rapport presenterar resultat från ett av dessa uppdrag.Eftersom uppdragen går ihop gällande inriktning och syfte är detta en sammanfattning av bägge uppdragen. Inom projektet Bestånds- och ekosystemanalys i stora sjöar gjordes en fördjupning i nuvarande datainsamling för att hitta förbättringar på hur man förvaltar fisket och ekosystemen.Inom projektet Miljöövervakning stora sjöarna utvärderades datainsamlingen och hur den utförs utifrån krav och behov inom följande direktiv:VattendirektivetArt- och habitatdirektivetEU:s förordning gällande invasiva arterBåda uppdragen gällde stora delar av den löpande fiskerioberoende datainsamlingen av fisk och kräftor i de stora sjöarna. Man har särskilt fokuserat på de stora, långsiktiga uppdragen HaV har gett till SLU Aqua – Institutionen för akvatiska resurser:hydroakustiska expeditioner med tillhörande provtrålning i den fria vattenmassan för bedömning av status hos pelagisk fisk och kvantitativ uppskattning av beståndsstorlekprovfisken med bottensatta översiktsnät för bedömning av status för bentiska arterkräftprovfisken med standardiserade betade burar.Den fiskerioberoende datainsamlingen har varit särskilt viktig för resursförvaltningen. Bedömningar av statusen hos de viktigaste fisk- och kräftbestånden baseras på data från programmen och publiceras kontinuerligt i SLU:s webbportal Fiskbarometern https://fiskbarometern.se/rapport/2023.Den fiskeriberoende datainsamlingen (till exempel fångststatistik från fisket) är också viktig för resursförvaltningen. Resultaten används inom flera områden som styr fisket, exempelvis licensprövningar, utfärdande av redskapsdispenser, utformning av tekniska fiskeregler, prioritering av fiskevårdsåtgärder med mera.Vattenförvaltningsförordningen ställer krav på kontrollerande och operativ övervakning av en rad biologiska kvalitetselement som används för bedömning av ekologisk status. Ett av dessa är fisk.Resultat från fiskundersökningar används därför också inom ramen för vattenförvaltningen. Enligt vattendirektivet ska särskild hänsyn tas till det som kallas betydande vatten, i Sverige handlar det om sjöar med en areal överstigande 100 km2. Storleken på sjöarna, att de ofta delas upp i flera vattenförekomster som fisk kan migrera mellan, den höga artrikedomen samt den ofta komplexa kombinationen av påverkanskällor medför utmaningar för bedömning av ekologisk status. I dagsläget saknas lämpliga bedömningsgrunder för fisk i betydande vatten och ofta används istället expertbedömningar.Viktigt hitta synergier mellan behov inom resurs- och vattenförvaltningÖvervakningen av fisk och kräftor ska möta behoven inom både resurs- och vattenförvaltningen. Dessa två uppdrag som nu rapporteras kan ses som ett första steg i att optimera övervakningen så att den på sikt kan tillfredsställa behov inom bägge områdena. I många fall finns betydande överlapp mellan behoven inom resurs- och vattenförvaltningen och därför behöver framtidens övervakning hitta välavvägda upplägg som genererar synergieffekter. Utvecklingen av övervakningen och dess användning inom olika förvaltningsområden behöver också samordnas med länsstyrelser, vattenvårdsförbund och andra relevanta aktörer.Betydelsen av målbilder och referenstillståndEn utmaning inom både resurs- och vattenförvaltningen är att definiera målbilder och referenstillstånd i sjöar som under lång tid varit lokalt påverkade av mänskliga aktiviteter. De stora sjöarna saknar dessutom referensområden som är opåverkade av lokala påverkanskällor. Påverkan går ofta långt tillbaka i historien, långt innan man började med datainsamling på fisk, därför är det också svårt att jämföra med opåverkade referensperioder.De båda uppdragen poängterar därför betydelsen av dels tydliga och välformulerade målbilder som tar hänsyn till lämpliga tidsperspektiv och dels att målformuleringar och uppföljning förankras med berörda aktörer som är involverade i resurs- och vattenförvaltningen. Viktigt är också att identifiera och hantera mål som står i konflikt med varandra, exempelvis gällande övergödning som sänker vattenkvalitet men i gengäld kan ge ökad resursproduktion.Betydelsen av geografisk täckningResultaten från de parallella uppdragen understryker behovet av övervakning med en god täckning av olika delområden i sjöarna. Det är statistiskt fördelaktigt med undersökningar i många olika delområden jämfört med en hög ansträngning i ett fåtal delområden. Förbättrad täckning ökar dessutom möjligheten att kunna följa och bedöma ekologisk status i de mindre vattenförekomster inom de stora sjöarna där det just nu inte sker någon datainsamling med avseende på fisk.En god täckning ger även data om fler geografiskt avgränsade delbestånd vilket kan ge bättre bedömningar av fiskresurserna. Då kan programmen också på ett bättre sätt fånga upp olika typer av habitat och olika miljö- och påverkansgradienter. Det kan bli lättare att bedöma effekter av fiske och andra påverkanskällor och även att identifiera och bevara de viktigaste områdena för fisken. Bättre täckning kan också öka sannolikheten att upptäcka och följa upp förekomsten av invasiva arter.Utveckling av indikatorer för uppföljningBåde inom resurs- och vattenförvaltningen används indikatorer för att bedöma status (hos fisk- och kräftbestånden samt miljön) och hur fiskbestånden utvecklas över tid. Indikatorerna som används är idag olika för resurs- respektive vattenförvaltningen men det finns tematiskt överlapp och behov av samordning i utvecklingen av indikatorer och tillhörande referensnivåer.De indikatorer som hittills har utvecklats för att bedöma ekologisk status i svenska sjöar kan inte tillämpas i större sjöar. Därför finns ett behov att utveckla nya indikatorer specifikt för dessa. Vissa påverkanskällor bedömdes vara särskilt viktiga att fånga upp. Dessa var övergödning, hydromorfologisk påverkan och påverkan på konnektivitet. Framtida arbete behöver identifiera hur dessa påverkanskällor påverkar enskilda fisk- och skaldjursbestånd och ekosystemet samt utveckla lämpliga indikatorer som kan följa utvecklingen.Det sker för tillfället en utveckling av indikatorer för att bättra kunna bedöma bestånden av fisk och kräfta (Nadaffi med flera 2023). Förhoppningsvis kan en del av dessa metoder och ansatser även tillämpas i utvecklingen av indikatorer inom vattenförvaltningen. Exempelvis används indikatorer för uppföljning av havsmiljödirektivet också för bedömning av beståndens status ur ett resursperspektiv (Östman med flera 2023).Urvalet av indikatorer som används inom förvaltningen kan få betydelse för prioriteringar inom datainsamlingen. Kraven på data kan skilja sig mellan olika indikatorer vilket innebär att olika indikatorer har olika behov vad gäller provtagningsdesign.Utveckling av nya metoder för datainsamlingÖkade krav och behov när både vatten- och resursförvaltning ska optimeras, i kombination med ytterligare aspekter som införande av ekosystembaserad förvaltning och krav på att antalet fiskar som dödas i undersökningarna ska minska, innebär att övervakningens metoder behöver utvecklas. Detta kan delvis lösas genom att man ser över utformning, inriktning och omfattning av befintlig övervakning men det kan också innebära att man behöver komplettera datainsamlingen med andra, nya, metoder.Nuvarande övervakning fångar dessutom inte upp alla relevanta arter, exempelvis gädda som är viktig för både fisket och ekosystemen, varför alternativa metoder som kan följa fler arter behövs. De senaste åren har det skett en teknisk utveckling av insamlings- och analysmetoder för fisk och kräftor (e-DNA, akustik till exempel) vilket kan vara aktuellt att implementera. Revidering av metodik inom övervakning tar dock tid och innebär, initialt, högre kostnader.Förutom fiskerioberoende metoder och den fiskeriberoende datainsamlingen som görs idag lyfter bägge rapporterna möjligheten att samla in ytterligare data från fisket som en alternativ metod. Trots att det finns skillnader i val av metoder, upplägg och prioriteringar kan dessutom samverkan med våra grannländer också vara ett sätt att utveckla datainsamlingen och dess tillämpningar inom både vatten- och resursförvaltningen.
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2. |
- Eckerström-Liedholm, Simon, 1988-
(author)
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Behavioural, physiological and morphological correlates of life-history in killifishes − a macroevolutionary approach
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Life-histories commonly evolve along a continuum from short-lived and fecund, to long-lived and less fecund. Because life-history traits are mostly components of reproduction and survival, understanding the causes and consequences of life-history variation is at the core of evolutionary biology. This thesis aims to identify what other key traits (e.g. behavioural, physiological and morphological traits) covary with life-history, and why. Numerous hypotheses describe how life-history might be associated with other traits, with life-history trade-offs often considered to be a primary driver of any such relationships. For example, since resources are limited, increased investment in one trait must lead to decreased investment in one or several other traits, all else equal. Hypotheses on the relationship between life-history and other traits have been tested in many studies, but empirical studies in controlled experimental settings are rare. In this thesis I explore how behaviour, physiology and morphology relate to variation along the life-history continuum from fast to slow, in a system with substantial variation in life-history traits - the killifishes.I began by exploring the patterns of egg to body size allometry in killifishes (Paper I), where species with faster life-histories showed indications of constraints on the independent evolution of egg size and body size. Furthermore, I found evidence of differences in variance and in the rates of evolution of egg size and body size across species, potentially caused by the colonisation of ephemeral habitats, which could have selected for adaptations that lead to differences in size.I then performed a comparative common garden study (Paper II) of the pace-of-life syndrome hypothesis, which predicts that species with fast life-histories should take larger risks in order to maintain their increased reproductive rate. I obtained data on risk taking behaviours, including movement, tendency to enter an open environment, and aggressiveness, in addition to metabolic rate, for 20 species of killifish, with multiple replicates per species. The results indicated trait dependent associations with life-history, where aggression seemed to correlate positively with speed of life-history, in congruence with our prediction.Next, my colleagues and I assessed the association between life-history and sexual selection (Paper III), in order to determine if investment in secondary sexual traits might be traded off against survival in killifish. Fin size was found to be negatively associated with escape performance in a simulated predator attack, suggesting survival costs for individuals with large fins. Importantly, fin size was also positively associated with the speed of life-history, supporting the hypothesis that costs to survival probability is lower in fast-living species.Lastly, I tested the hypothesized negative covariation between relative brain size and speed of life-history, by collecting and analysing brain size measurements for 21 species of killifish (Paper IV). Surprisingly, a positive relationship between speed of life-history and relative brain size was found for adults, although juveniles did not differ in relative brain size. This implies at least one of two things: either there is no need to trade off brain size with life-history since resource acquisition is higher, or brain size and life-history are traded-off with other traits.In conclusion, I show that previously found trade-offs between life-history and investment in other costly traits are only sometimes present, when tested in a system with substantial divergences in the speed of life-history. I also provide evidence for a trait dependent association between life-history and among species differences in risk-taking and metabolic rate.
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3. |
- Eckerström-Liedholm, Simon, 1988-, et al.
(author)
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Fast life-histories are associated with larger brain size in killifishes
-
Other publication (other academic/artistic)abstract
- Comparative studies suggest a negative relationship between pace of life-history, and relative energetic investment into brain size. However, since brain size typically evolves as a correlated response to selection on body size, any lag in brain size evolution will result in a shift in relative brain size (e.g. small body – large relative brain size).Coevolution between body size and life-history hence has the potential to drive secondary associations between relative brain size and life-history, when body size is correlated with life history. However, as far as we know, the relationship between relative brain size and life-history strategy has not been examined in systems that simultaneously present marked contrasts in life-history but no concordant shifts in body size. Using a common garden approach, we test the association between relative brain size and life-history in 21 species of killifish; a study system that fulfils the aforementioned requirements. Contrary to the prediction that brain size evolves through energetic trade-offs with life-history, we found that adults, but not juveniles, of fast-living species had larger relative brain sizes. Rather than an energetic link to life-history, our results suggest that fast- and slow-living species differ in terms of how cognitively demanding environments they inhabit are, or alternatively in the ontogenetic timing of somatic vs. neural growth.
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4. |
- Eckerström-Liedholm, Simon, et al.
(author)
-
Macroevolutionary evidence suggests trait-dependent coevolution between behavior and life-history
- 2019
-
In: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 73:11, s. 2312-2323
-
Journal article (peer-reviewed)abstract
- Species with fast life-histories typically prioritize current over future reproductive events, compared to species with slow life-histories. These species therefore require greater energetic input into reproduction, and also likely have less time to realize their reproductive potential. Hence, behaviors that increase access to both resources and mating opportunities, at a cost of increased mortality risk, could coevolve with the pace of life-history. However, whether this prediction holds across species, remains untested under standardized conditions. Here, we test how risky behaviors, which facilitate access to resources and mating opportunities (i.e., activity, boldness, and aggression), along with metabolic rate, coevolve with the pace of life-history across 20 species of killifish that present remarkable divergences in the pace of life-history. We found a positive association between the pace of life-history and aggression, but interestingly not with other behavioral traits or metabolic rate. Aggression is linked to interference competition, and in killifishes is often employed to secure mates, while activity and boldness are more relevant for exploiting energetic resources. Our results suggest that the trade-off between current and future reproduction plays a more prominent role in shaping mating behavior, while behaviors related to energy acquisition may be influenced by ecological factors.
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5. |
- Eckerström-Liedholm, Simon, 1988-, et al.
(author)
-
Macroevolutionary evidence suggests trait-dependent coevolution between behaviour and life-history
-
Other publication (other academic/artistic)abstract
- Species with fast life-histories prioritize current over future reproduction, which ought to require greater energetic resources, but also results in a shorter time-period to realize their reproductive potential, compared to slow life-histories, which prioritize future reproduction. Hence, behaviours that increase access to both resources and mating opportunities, at a cost of increased mortality risk, are thought to coevolve with the pace of life-history. However, whether this prediction holds across species, is yet to be tested under standardized conditions. Here, we test how potentially risky behaviours, which facilitate access to resources and mating opportunities (i.e. activity, boldness and aggression), along with metabolic rate, correlates with the pace of life-history across 20 species of killifish, which present a remarkable divergence in the pace of their life-histories. We found a positive correlation between the pace of life-history and aggression, but not with any other behavioural traits or metabolic rate. Aggression is often expressed in the context of mating, while the other behaviours we measured might be more relevant for access to energetic resources. Our results therefore suggest that the trade-off between current and future reproduction plays a more prominent role in shaping mating behaviour, while behaviours related to acquisition of energetic resources may be more affected by ecological factors.
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6. |
- Eckerström-Liedholm, Simon, et al.
(author)
-
Time-limited environments affect the evolution of egg-body size allometry
- 2017
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In: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 71:7, s. 1900-1910
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Journal article (peer-reviewed)abstract
- Initial offspring size is a fundamental component of absolute growth rate, where large offspring will reach a given adult body size faster than smaller offspring. Yet, our knowledge regarding the coevolution between offspring and adult size is limited. In time-constrained environments, organisms need to reproduce at a high rate and reach a reproductive size quickly. To rapidly attain a large adult body size, we hypothesize that, in seasonal habitats, large species are bound to having a large initial size, and consequently, the evolution of egg size will be tightly matched to that of body size, compared to less time-limited systems. We tested this hypothesis in killifishes, and found a significantly steeper allometric relationship between egg and body sizes in annual, compared to nonannual species. We also found higher rates of evolution of egg and body size in annual compared to nonannual species. Our results suggest that time-constrained environments impose strong selection on rapidly reaching a species-specific body size, and reproduce at a high rate, which in turn imposes constraints on the evolution of egg sizes. In combination, these distinct selection pressures result in different relationships between egg and body size among species in time-constrained versus permanent habitats.
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7. |
- Fong, Stephanie, 1990-
(author)
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Brain morphology and behaviour in the guppy (Poecilia reticulata) : Effects of plasticity and mosaic brain evolution
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Understanding how brains have evolved and subsequently culminated in the huge variation in brain morphology among contemporary vertebrate species has fascinated researchers for many decades. It has been recognized that brain morphology is both genetically and environmentally determined. Adaptations to ecological challenges, for one, has been proposed to be a major force in brain diversification processes. Considering the large energetic costs of neural tissue, it is believed that brain evolution is a highly complex process, involving a delicate balance between the corresponding costs and benefits. Using the guppy (Poecilia reticulata) as the model organism, I first examined the conditions under which diversity in brain morphology is generated. This was done by investigating factors known to exert an influence on brain plasticity, namely environmental and cognitive effects (Paper I). Existing studies generally indicate that the provision of environmental enrichment lead to the enlargement of specific brain structures. While plastic alterations in brain morphology was found to respond to environmental complexity in my study, successful performance in two cognitive tasks did not produce any significant changes. I next assessed the feasibility of the mosaic brain evolution hypothesis by artificially selecting for an increase and decrease in the relative size of the telencephalon (Paper II). Telencephalon size was shown to respond rapidly to divergent selection pressures, with no substantial changes in any of the other brain regions. A comparison with wild fish revealed that fish from the unselected control treatment had telencephalon sizes most similar to that of wild populations, whereas both up-selected and down-selected fish had considerably larger and smaller telencephalon, respectively. I tested fish from the artificial selection lines in a test battery to determine if known differences in telencephalon size affects boldness (Paper III). Individuals were subjected to an emergence test, an open field test and a novel object test. I found no differences in boldness levels across selection treatments, but distinct sex differences were noted whereby males were more active and bolder. The cognitive benefits associated with a larger telencephalon were examined in males in a test of self-control (Paper IV). Guppies from the up-selected lines attained a steeper learning curve and made more correct detours compared to their down-selected conspecifics. In conclusion, I provide experimental evidence for the mosaic brain evolution hypothesis by showing that a specific brain region (telencephalon) can evolve rapidly and independently under directed selection. Future tests on other cognitive benefits as well as implicated costs, together with underlying neuronal changes would help to further unravel the factors governing brain evolution.
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8. |
- Fong, Stephanie, 1990-, et al.
(author)
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Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (Poecilia reticulata)
-
Other publication (other academic/artistic)abstract
- The vertebrate brain displays enormous morphological variation and the quest to understand the evolutionary causes and consequences of this variation has spurred over a century of research. The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently, is a highly influential idea in this research field. Here we provide the first experimental support for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After three generations of selection on relative telencephalon volume in replicated up-selected, down-selected and control selection lines, we found substantial overall changes in relative telencephalon size (i.e. relative to brain size), but no changes in other brain regions. The differences were not evident at birth but present at the time of sexual maturation. There was a non-significant trend towards asymmetry in the response to selection in both sexes, with larger changes occurring during upwards selection as opposed to downwards selection. Our results demonstrate that independent evolutionary changes in specific brain regions can be an important mechanism during cognitive evolution.
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9. |
- Fong, Stephanie, et al.
(author)
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Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (Poecilia reticulata)
- 2021
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In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:46
-
Journal article (peer-reviewed)abstract
- The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently during cognitive evolution, is an important idea to understand how brains evolve with potential implications even for human brain evolution. Here, we provide the first experimental evidence for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After four generations of selection on relative telencephalon volume (relative to brain size), we found substantial changes in telencephalon size but no changes in other regions. Further comparisons revealed that up-selected lines had larger telencephalon, while down-selected lines had smaller telencephalon than wild Trinidadian populations. Our results support that independent evolutionary changes in specific brain regions through mosaic brain evolution can be important facilitators of cognitive evolution.
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10. |
- Hansen Wheat, Christina, et al.
(author)
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Behavioural correlations of the domestication syndrome are decoupled in modern dog breeds
- 2019
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10
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Journal article (peer-reviewed)abstract
- Domestication is hypothesized to drive correlated responses in animal morphology, physiology and behaviour, a phenomenon known as the domestication syndrome. However, we currently lack quantitative confirmation that suites of behaviours are correlated during domestication. Here we evaluate the strength and direction of behavioural correlations among key prosocial (sociability, playfulness) and reactive (fearfulness, aggression) behaviours implicated in the domestication syndrome in 76,158 dogs representing 78 registered breeds. Consistent with the domestication syndrome hypothesis, behavioural correlations within prosocial and reactive categories demonstrated the expected direction-specificity across dogs. However, correlational strength varied between dog breeds representing early (ancient) and late (modern) stages of domestication, with ancient breeds exhibiting exaggerated correlations compared to modern breeds across prosocial and reactive behaviours. Our results suggest that suites of correlated behaviours have been temporally decoupled during dog domestication and that recent shifts in selection pressures in modern dog breeds affect the expression of domestication-related behaviours independently.
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11. |
- Herbert-Read, James E., et al.
(author)
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How predation shapes the social interaction rules of shoaling fish
- 2017
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In: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 284:1861
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Journal article (peer-reviewed)abstract
- Predation is thought to shape the macroscopic properties of animal groups, making moving groups more cohesive and coordinated. Precisely how predation has shaped individuals' fine-scale social interactions in natural populations, however, is unknown. Using high-resolution tracking data of shoaling fish (Poecilia reticulata) from populations differing in natural predation pressure, we show how predation adapts individuals' social interaction rules. Fish originating from high predation environments formed larger, more cohesive, but not more polarized groups than fish from low predation environments. Using a new approach to detect the discrete points in time when individuals decide to update their movements based on the available social cues, we determine how these collective properties emerge from individuals' microscopic social interactions. We first confirm predictions that predation shapes the attraction-repulsion dynamic of these fish, reducing the critical distance at which neighbours move apart, or come back together. While we find strong evidence that fish align with their near neighbours, we do not find that predation shapes the strength or likelihood of these alignment tendencies. We also find that predation sharpens individuals' acceleration and deceleration responses, implying key perceptual and energetic differences associated with how individuals move in different predation regimes. Our results reveal how predation can shape the social interactions of individuals in groups, ultimately driving differences in groups' collective behaviour.
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12. |
- Höglund, Jacob, et al.
(author)
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Low MHC variation in isolated island populations of the Natterjack toad (Bufo calamita)
- 2015
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In: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 16:4, s. 1007-1010
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Journal article (peer-reviewed)abstract
- We studied variation at the class II gene of the major histocompatibility complex (MHC) in Natterjack toad populations (Bufo [Epidalea] calamita) on islands off the west coast of Sweden. These isolated populations have previously been shown to exhibit low levels of neutral genetic variation. On seven investigated islands we found only two different MHC alleles, indicating that the genetic variation at this locus is also low. The two alleles were found in all populations, although in one population there was only a single heterozygous individual. The Swedish toads showed similar low levels of MHC variation as revealed by previously published data from populations in northern Europe. We did not find a correlation between MHC and neutral genetic variation (as determined by AFLP). However, our findings show that reduced genetic variation in the Swedish Natterjack toads is not restricted to neutral markers, but is likewise reflected at the MHC.
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13. |
- Kotrschal, Alexander, et al.
(author)
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Artificial selection on relative brain size in the guppy reveals costs and benefits of evolving a larger brain
- 2013
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In: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 23:2, s. 168-171
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Journal article (peer-reviewed)abstract
- The large variation in brain size that exists in the animal kingdom has been suggested to have evolved through the balance between selective advantages of greater cognitive ability and the prohibitively high energy demands of a larger brain (the "expensive-tissue hypothesis" [1]). Despite over a century of research on the evolution of brain size, empirical support for the trade-off between cognitive ability and energetic costs is based exclusively on correlative evidence [2], and the theory remains controversial [3, 4]. Here we provide experimental evidence for costs and benefits of increased brain size. We used artificial selection for large and small brain size relative to body size in a live-bearing fish, the guppy (Poecilia reticulata), and found that relative brain size evolved rapidly in response to divergent selection in both sexes. Large-brained females outperformed small-brained females in a numerical learning assay designed to test cognitive ability. Moreover, large-brained lines, especially males, developed smaller guts, as predicted by the expensive-tissue hypothesis [1], and produced fewer offspring. We propose that the evolution of brain size is mediated by a functional trade-off between increased cognitive ability and reproductive performance and discuss the implications of these findings for vertebrate brain evolution.
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14. |
- Kotrschal, Alexander, et al.
(author)
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Sex-specific plasticity in brain morphology depends on social environment of the guppy, Poecilia reticulata
- 2012
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In: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 66:11, s. 1485-1492
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Journal article (peer-reviewed)abstract
- The vertebrate brain is a remarkably plastic organ, which responds quickly to environmental changes. However, to date, studies investigating plasticity in brain morphology have focused mostly on the physical properties of the surrounding environment, and little is known about brain plasticity in response to the social environment. Moreover, sex differences in brain plasticity remain virtually unexplored. Here, we tested how the social environment influenced brain morphology in adult males and females using experimental manipulation of the sex composition of social pairs (same sex vs. mixed sex) in the guppy (Poecilia reticulata). We detected substantial sex-specific plasticity in both the overall brain size (controlling for body size) and separate brain structures. The brain size was larger in males that interacted with females, and female optic tectum was larger in female-only groups. Overall, females had larger olfactory bulbs and cerebellum in comparison to males. While net sexual dimorphism in the brain structure can be explained in light of the known differences in boldness and foraging behaviour between the sexes, our results also support that cognitive demands associated with courtship behaviour can lead to plastic changes in the brain size. Our findings demonstrate that not only social environment can generate rapid, plastic responses in the vertebrate brain but also that such responses can depend strongly on sex.
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15. |
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16. |
- Kotrschal, Alexander, et al.
(author)
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The mating brain : early maturing sneaker males maintain investment into the brain also under fast body growth in Atlantic salmon (Salmo salar)
- 2014
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In: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 28:6, s. 1043-1055
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Journal article (peer-reviewed)abstract
- It has been suggested that mating behaviours require high levels of cognitive ability. However, since investment into mating and the brain both are costly features, their relationship is likely characterized by energetic trade-offs. Empirical data on the subject remains equivocal. We investigated if early sexual maturation was associated with brain development in Atlantic salmon (Salmo salar), in which males can either stay in the river and sexually mature at a small size (sneaker males) or migrate to the sea and delay sexual maturation until they have grown much larger (anadromous males). Specifically, we tested how sexual maturation may induce plastic changes in brain development by rearing juveniles on either natural or ad libitum feeding levels. After their first season we compared brain size and brain region volumes across both types of male mating tactics and females. Body growth increased greatly across both male mating tactics and females during ad libitum feeding as compared to natural feeding levels. However, despite similar relative increases in body size, early maturing sneaker males maintained larger relative brain size during ad libitum feeding levels as compared to anadromous males and females. We also detected several differences in the relative size of separate brain regions across feeding treatments, sexes and mating strategies. For instance, the relative size of the cognitive centre of the brain, the telencephalon, was largest in sneaker males. Our data support that a large relative brain size is maintained in individuals that start reproduction early also during fast body growth. We propose that the cognitive demands during complex mating behaviours maintain a high level of investment into brain development in reproducing individuals.
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17. |
- Kärvemo, Simon, et al.
(author)
-
Dynamics of spruce bark beetle infestation spots : Importance of local population size and landscape characteristics after a storm disturbance
- 2014
-
In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 334, s. 232-240
-
Journal article (peer-reviewed)abstract
- The European spruce bark beetle Ips typographus (L) is one of the most important pests of mature Norway spruce in Europe. Outbreaks are often triggered by large-scale storm disturbances, which provide the beetles with a large surplus of suitable breeding material in the form of wind-felled spruces in storm gaps. Due to high reproductive success in storm-felled trees beetle populations may become large enough to overcome defences of living trees in the summers following a storm. From a management perspective, procedures enabling reliable predictions of local tree mortality based on the size of storm gaps would be highly valuable. Thus, in the presented study we recorded tree mortality caused by I. typographus during a five-year period around 35 storm gaps hosting local beetle populations, differing in size with 0-818 colonised wind-felled spruces. We then developed models to address the following questions. How does local population size in wind-felled trees influence tree mortality in the subsequent years? What other storm gap and landscape variables influence tree mortality? How does the tree mortality compare with results of earlier studies? Four gap variables and three landscape variables at four scales (500-2000 m) were included in the models. In total, 21,486 standing spruces were killed by I. typographus around the gaps. Tree mortality started in the second summer after the storm and peaked in the third year around most gaps. The models explained most of the variation in tree mortality around the gaps during the five-year period, accounting for 60-67% of the deviance from null models. The most important variable influencing tree mortality was the number of colonised wind-felled trees (a proxy for the size of local populations), explaining 60-64% of the null deviance. Other gap variables that significantly, and positively, affected tree mortality were the mean diameter of colonised wind-felled trees and basal area of living spruce trees in stands adjacent to the storm gaps. Of the landscape variables, the area of storm gaps in the surrounding landscape explained most of the variation in the models. The area of spruce forest also had a significant positive effect at the largest scales. The finding that the number of colonised wind-felled trees was closely related to the number of killed trees in the forest around the gaps implies that areas with numerous large storm gaps should be harvested first after large-scale storm disturbances. (C) 2014 Elsevier B.V. All rights reserved.
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18. |
- Marzal, Julia Carolina Segami, et al.
(author)
-
Cryptic female Strawberry poison frogs experience elevated predation risk when associating with an aposematic partner
- 2017
-
In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:2, s. 744-750
-
Journal article (peer-reviewed)abstract
- Population divergence in sexual signals may lead to speciation through prezygotic isolation. Sexual signals can change solely due to variation in the level of natural selection acting against conspicuousness. However, directional mate choice (i.e., favoring conspicuousness) across different environments may lead to gene flow between populations, thereby delaying or even preventing the evolution of reproductive barriers and speciation. In this study, we test whether natural selection through predation upon mate-choosing females can favor corresponding changes in mate preferences. Our study system, Oophaga pumilio, is an extremely color polymorphic neotropical frog with two distinctive antipredator strategies: aposematism and crypsis. The conspicuous coloration and calling behavior of aposematic males may attract both cryptic and aposematic females, but predation may select against cryptic females choosing aposematic males. We used an experimental approach where domestic fowl were encouraged to find digitized images of cryptic frogs at different distances from aposematic partners. We found that the estimated survival time of a cryptic frog was reduced when associating with an aposematic partner. Hence, predation may act as a direct selective force on female choice, favoring evolution of color assortative mating that, in turn, may strengthen the divergence in coloration that natural selection has generated.
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19. |
- Nilsson-Oertman, V., et al.
(author)
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Ontogenetic changes in genetic variances of age-dependent plasticity along a latitudinal gradient
- 2015
-
In: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 115:4, s. 366-378
-
Journal article (peer-reviewed)abstract
- The expression of phenotypic plasticity may differ among life stages of the same organism. Age-dependent plasticity can be important for adaptation to heterogeneous environments, but this has only recently been recognized. Whether age-dependent plasticity is a common outcome of local adaptation and whether populations harbor genetic variation in this respect remains largely unknown. To answer these questions, we estimated levels of additive genetic variation in age-dependent plasticity in six species of damselflies sampled from 18 populations along a latitudinal gradient spanning 3600 km. We reared full sib larvae at three temperatures and estimated genetic variances in the height and slope of thermal reaction norms of body size at three points in time during ontogeny using random regression. Our data show that most populations harbor genetic variation in growth rate (reaction norm height) in all ontogenetic stages, but only some populations and ontogenetic stages were found to harbor genetic variation in thermal plasticity (reaction norm slope). Genetic variances in reaction norm height differed among species, while genetic variances in reaction norm slope differed among populations. The slope of the ontogenetic trend in genetic variances of both reaction norm height and slope increased with latitude. We propose that differences in genetic variances reflect temporal and spatial variation in the strength and direction of natural selection on growth trajectories and age-dependent plasticity. Selection on age-dependent plasticity may depend on the interaction between temperature seasonality and time constraints associated with variation in life history traits such as generation length.
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20. |
- Ogonowski, Martin, et al.
(author)
-
Microplastics could be marginally more hazardous than natural suspended solids – A meta-analysis
- 2023
-
In: Ecotoxicology and Environmental Safety. - 0147-6513 .- 1090-2414. ; 264
-
Journal article (peer-reviewed)abstract
- Microplastics (MP) are perceived as a threat to aquatic ecosystems but bear many similarities to suspended sediments which are often considered less harmful. It is, therefore pertinent to determine if and to what extent MP are different from other particles occurring in aquatic ecosystems in terms of their adverse effects. We applied meta-regressions to toxicity data extracted from the literature and harmonized the data to construct Species Sensitivity Distributions (SSDs) for both types of particles. The results were largely inconclusive due to high uncertainty but the central tendencies of our estimates still indicate that MP could be marginally more hazardous compared to suspended sediments. In part, the high uncertainty stems from the general lack of comparable experimental studies and dose-dependent point estimates. We therefore argue that until more comparable data is presented, risk assessors should act precautionary and treat MP in the 1–1000 µm size range as marginally more hazardous to aquatic organisms capable of ingesting such particles.
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21. |
- Persson, John, et al.
(author)
-
Beståndsutveckling för signalkräfta i de stora sjöarna 2023 : resultat inom projektet datainsamling sötvattenskräftor fram till och med 2023
- 2024
-
Reports (other academic/artistic)abstract
- Efter att flodkräftan slagits ut av kräftpest i samtliga stora sjöarna introducerades signalkräfta 1969 i Vättern, Hjälmaren och Mälaren. Idag finns livskraftiga och fiskbara bestånd av signalkräfta i Hjälmaren och Vättern. I Vänern har det skett två lagliga utsättningar av signalkräfta, den första skedde 1988 i sjöns norra delar (Länsstyrelsen i Västra Götalands län 2011). I Vänern är beståndsutvecklingen positiv och större andelen av landningarna tas i sydöstra delarna av sjön. Beståndet av signalkräfta i Mälaren, som till en början utvecklades gynnsamt, minskade kraftigt efter år 2000. Numera finns inget yrkesfiske på kräftor i Mälaren med anledning av de låga tätheterna. De senaste åren finns dock tecken på att kräftbestånden återhämtat sig i åtminstone delar av sjön.Denna rapport redovisar resultaten från provfiskena och provtagningen av yrkesfiskares landningar av signalkräfta i Hjälmaren, Vättern, Vänern samt Mälaren under 2023. Resultaten jämförs även med en sammanställning av tidigare års data (2009–2022). Resultaten från analyserna ligger bland annat till grund för SLU Aqua’s bedömning av den biologiska statusen för arten i de olika sjöarna (Sveriges lantbruksuniversitet 2023).Beståndssituationen skiljer sig både inom och mellan de olika provfiskade lokalerna i sjöarna. Samtliga sex lokaler som SLU provfiskar i Vättern har hög fångst per ansträngning. På dessa lokaler (utom en i norra delarna) har dock medelstorleken minskat samtidigt som antalet kräftor har ökat. I Hjälmaren undersöks tre lokaler och även där är fångsterna jämförelsevis höga. På en av dessa lokaler har antalet kräftor ökat och medelstorlek samt andelen kräftor över minimimåttet (11 cm) minskat. För övriga två lokaler i sjön finns ingen tydlig trend rörande kräftornas medelstorlek eller antal. I Vänern provfiskar SLU endast två lokaler. Kräftbestånden i Vänern befinner sig i en expansionsfas där det sker en långsam men stadig ökning av kräftornas antal och medelstorlek. Nuvarande landningar ligger dock (likt föregående) år på en betydligt lägre nivå jämfört med Vättern och Hjälmaren. Under provfiskeperioden 2010-2023 har det totala antalet kräftor och andelen över minimimåttet ökat på den ena av lokalerna. På den andra lokalen finns inga tydliga trender. Inom yrkesfisket i Mälaren rapporteras landningar endast på några kilon sedan 2000, och fritidsfisket i sjön har tidigare endast förekommit i liten omfattning. På de provfiskade lokalerna i Mälaren har antal kräftor och andelen kräftor över minimimåttet successivt ökat från 2010. Det är möjligt att det sker en förändring av bestånden i Mälaren då det under senare år finns tecken på en återhämtning genom inrapporterad fångstdata. SLU Aqua kommer tillsammans med ansvariga länsstyrelser runt Mälaren att lägga upp en bättre strategi för att följa kräftbeståndens utveckling de kommande åren.
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22. |
- Persson, John, et al.
(author)
-
Signalkräftbeståndens utveckling i de stora sjöarna 2021 – resultat från fångstprovtagning och provfske inom projekt datainsamling sötvattenskräftor
- 2022
-
Reports (other academic/artistic)abstract
- Denna rapport redovisar resultat från provfisken och provtagning av yrkesfiskares fångster av signalkräfta iHjälmaren, Vättern, Vänern och Mälaren år 2021, med en resultatsammanställning och jämförelse med tidigare års data (2009–2021). Resultaten skiljer sig inom och mellan de olika lokalerna i sjöarna. Generellt sett ger samtliga sex kräftlokaler i Vättern höga fångster av kräftor särskilt sett till antal fångade kräftor. På alla lokaler (utom en i norra Vättern) så har medelstorleken minskat samtidigt som antalet kräftor har ökat. I Hjälmaren följer SLU tre kräftlokaler. Även här är fångsterna generellt höga. På en av lokalerna i Hjälmaren har antalet kräftor ökat och medelstorlek och andelen kräftor över minimimåttet minskat. För övriga lokaler i sjön syns ingen tydlig trend rörande kräftornas medelstorlek och antal. I Vänern har SLU två kräftlokaler. I Vänern befinner sig kräftorna i en expansionsfas och fångsterna är fortfarande på en betydligt blygsammare nivå jämfört med Vättern och Hjälmaren. Det sker dock en långsam generell ökning av kräftornas antal och medelstorlek. Under den provfiskade perioden visar den ena av de två lokalerna ingen signifikant förändring medan den andra har ökat antal kräftor men också en ökad andel kräftor över minimimåttet. I Mälaren sker inga fångster i yrkesfisket sedan 2000 och fritidsfisket har tidigare endast tagit sporadiska fångster. Det är möjligt att det nu sker en förändring av bestånden i Mälaren då det på senare år finns vissa tecken på en återhämtning om än från mycket låga nivåer. SLU Aqua kommer tillsammans med länsstyrelserna runt sjön att lägga upp en strategi för att följa Mälarens kräftbestånds utveckling närmare de kommande åren. På den provfiskade lokalen i Mälaren har antal kräftor och andelen kräftor över minimimåttet ökat. Under 2021 utfördes även ett burexperiment på en av lokalerna i Vättern där skillnaden i kräftfångster mellan yrkesfiskeburar och provfiskeburar jämfördes över en, två och fem nätter. Resultaten visade att både storleksstrukturen och antalet fångade kräftor påverkas av hur länge burarna ligger ute och fiskar.
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23. |
- Persson, John, et al.
(author)
-
Signalkräftbeståndens utveckling i de stora sjöarna 2022 – resultat från fångstprovtagning och provfiske inom projekt datainsamling sötvattenskräftor
- 2023
-
Reports (other academic/artistic)abstract
- Efter att flodkräftan slagits ut av kräftpest i samtliga av de stora sjöarna introducerades signalkräfta i Vättern, Hjälmaren och Mälaren med start 1969. Idag finns fiskbara bestånd av signalkräfta i huvuddelen av Hjälmaren och Vättern. I Vänern är bestånden på uppgång men större delen av fångsterna tas i sydöstra delen av sjön. Beståndet av signalkräfta i Mälaren, som till en början utvecklades gynnsamt, minskade kraftigt efter år 2000. Idag finns inget yrkesfiske på kräftor i Mälaren, på grund av alltför låga fångster, men de senaste åren har visat tecken på viss återhämtning i sjön.Denna rapport redovisar resultat från provfisken och provtagning av yrkesfiskares fångster av signalkräfta i Hjälmaren, Vättern, Vänern samt Mälaren för 2022, med en resultatsammanställning och jämförelse med tidigare års data (2009–2021). Resultat från dessa analyser ligger bland annat till grund för hur SLU Aqua bedömer den biologiska statusen av arten i de olika sjöarna (SLU 2022). Resultaten skiljer sig inom och mellan de olika provfiskade lokalerna i sjöarna. Generellt sett ger samtliga sex lokaler i Vättern höga antal fångade kräftor. På alla lokaler (utom en i norra Vättern) så har medelstorleken minskat samtidigt som antalet kräftor har ökat. I Hjälmaren följer SLU tre lokaler. Även här är fångsterna jämförelsevis höga. På en av lokalerna i Hjälmaren har antalet kräftor ökat och medelstorlek och andelen kräftor över minimimåttet minskat. För övriga lokaler i sjön syns ingen tydlig trend rörande kräftornas medelstorlek och antal. I Vänern provfiskar SLU två lokaler. I Vänern befinner sig kräftorna i en expansionsfas och fångsterna är fortfarande på en betydligt lägre nivå jämfört med Vättern och Hjälmaren. Det sker dock en långsam ökning av kräftornas antal och medelstorlek. Under den provfiskade perioden visar den ena av de två lokalerna på ett ökat antal kräftor men också på en ökad andel kräftor över minimimåttet medan den till synes ökande trenden i den andra lokalen inte kan beläggas statistiskt. I Mälaren rapporteras inga fångster i yrkesfisket sedan 2000 och fritidsfisket har tidigare endast tagit sporadiska fångster. På den provfiskade lokalen i Mälaren har antal kräftor och andelen kräftor över minimimåttet ökat. Det är möjligt att det nu sker en förändring av bestånden i Mälaren då det på senare år finns vissa tecken på en återhämtning, om än från mycket låga nivåer. SLU Aqua kommer tillsammans med länsstyrelserna runt sjön att lägga upp en strategi för att följa Mälarens kräftbestånds utveckling närmare de kommande åren.
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24. |
- Richter-Boix, Alex, et al.
(author)
-
Local selection modifies phenotypic divergence among Rana temporaria populations in the presence of gene flow
- 2010
-
In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 19:4, s. 716-731
-
Journal article (peer-reviewed)abstract
- In ectotherms, variation in life history traits among populations is common and suggests local adaptation. However, geographic variation itself is not a proof for local adaptation, as genetic drift and gene flow may also shape patterns of quantitative variation. We studied local and regional variation in means and phenotypic plasticity of larval life history traits in the common frog Rana temporaria using six populations from central Sweden, breeding in either open-canopy or partially closed-canopy ponds. To separate local adaptation from genetic drift, we compared differentiation in quantitative genetic traits (Q(ST)) obtained from a common garden experiment with differentiation in presumably neutral microsatellite markers (F-ST). We found that R. temporaria populations differ in means and plasticities of life history traits in different temperatures at local, and in F-ST at regional scale. Comparisons of differentiation in quantitative traits and in molecular markers suggested that natural selection was responsible for the divergence in growth and development rates as well as in temperature-induced plasticity, indicating local adaptation. However, at low temperature, the role of genetic drift could not be separated from selection. Phenotypes were correlated with forest canopy closure, but not with geographical or genetic distance. These results indicate that local adaptation can evolve in the presence of ongoing gene flow among the populations, and that natural selection is strong in this system.
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25. |
- Rogell, Björn, et al.
(author)
-
Adaptive divergence in body size overrides the effects of plasticity across natural habitats in the brown trout
- 2013
-
In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:7, s. 1931-1941
-
Journal article (peer-reviewed)abstract
- The evolution of life-history traits is characterized by trade-offs between different selection pressures, as well as plasticity across environmental conditions. Yet, studies on local adaptation are often performed under artificial conditions, leaving two issues unexplored: (i) how consistent are laboratory inferred local adaptations under natural conditions and (ii) how much phenotypic variation is attributed to phenotypic plasticity and to adaptive evolution, respectively, across environmental conditions? We reared fish from six locally adapted (domesticated and wild) populations of anadromous brown trout (Salmo trutta) in one semi-natural and three natural streams and recorded a key life-history trait (body size at the end of first growth season). We found that population-specific reaction norms were close to parallel across different streams and Q(ST) was similar - and larger than F-ST - within all streams, indicating a consistency of local adaptation in body size across natural environments. The amount of variation explained by population origin exceeded the variation across stream environments, indicating that genetic effects derived from adaptive processes have a stronger effect on phenotypic variation than plasticity induced by environmental conditions. These results suggest that plasticity does not swamp the phenotypic variation, and that selection may thus be efficient in generating genetic change.
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26. |
- Rogell, Björn, et al.
(author)
-
Controlling for body size leads to inferential biases in the biological sciences
- 2020
-
In: Evolution Letters. - : Oxford University Press (OUP). - 2056-3744. ; 4:1, s. 73-82
-
Journal article (peer-reviewed)abstract
- Many traits correlate with body size. Studies that seek to uncover the ecological factors that drive evolutionary responses in traits typically examine these responses relative to associated changes in body size using multiple regression analysis. However, it is not well appreciated that in the presence of strongly correlated variables, the partial (i.e., relative) regression coefficients often change sign compared to the original coefficients. Such sign reversals are difficult to interpret in a biologically meaningful way, and could lead to erroneous evolutionary inferences if the true mechanism underlying the sign reversal differed from the proposed mechanism. Here, we use simulations to demonstrate that sign reversal occurs over a wide range of parameter values common in the biological sciences. Further, as a case-in-point, we review the literature on brain size evolution; a field that explores how ecological traits relate to the evolution of relative brain size (brain size relative to body size). We find that most studies show sign reversals and thus that the inferences of many studies in this field may be inconclusive. Finally, we propose some approaches to mitigating this issue.
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27. |
- Rogell, Björn, et al.
(author)
-
Fitness costs associated with low genetic variation are reduced in a harsher environment in amphibian island populations
- 2010
-
In: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11:2, s. 489-496
-
Journal article (pop. science, debate, etc.)abstract
- A basic premise of conservation geneticists is that low levels of genetic variation are associated with fitness costs in terms of reduced survival and fecundity. These fitness costs may frequently vary with environmental factors and should increase under more stressful conditions. However, there is no consensus on how fitness costs associated with low genetic variation change under natural conditions in relation to the stressfulness of the environment. On the Swedish west coast, natterjack toad Bufo calamita populations show a strong population genetic structure and large variation in the amount of within-population genetic variation. We experimentally examined the survival of natterjack larvae from six populations with different genetic variation in three thermal environments corresponding to (a) the mean temperature of natural ponds (stable, laboratory), (b) a high temperature environment occurring in desiccating ponds (stable, laboratory) and (c) an outdoor treatment mimicking the natural, variable thermal conditions (fluctuating, semi-natural). We found that larvae in the outdoor treatment had poorer survival than larvae in the stable environments suggesting that the outdoor treatment was more stressful. Overall, populations with higher genetic variation had higher larval survival. However, a significant interaction between treatments and genetic variation indicated that fitness costs associated with low genetic variation were less severe in the outdoor treatment. Thus, we found no support for the hypothesis that fitness costs associated with low genetic variation increase under more stressful conditions. Our results suggest that natural thermal stress may mask fitness losses associated with low genetic variation in these populations.
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28. |
- Rogell, Björn, 1979-, et al.
(author)
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Genetic structure in peripheral populations of the natterjack toad, Bufo calamita, as revealed by AFLP
- 2010
-
In: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11:1, s. 173-181
-
Journal article (peer-reviewed)abstract
- Decreased fitness due to loss of genetic variation is a well recognised issue in conservation biology. Along the Swedish west coast, the endangered natterjack toad (Bufo calamita) occurs on, for the species, highly unusual habitat of rocky islands. Although the toads inhabit a restricted geographical area (maximum distance between the populations is 71 km), the fragmented nature of the landscape makes the genetic properties of the populations of conservation interest. However, lack of genetic variation found using conventional methods (microsatellites) has impeded genetic studies within these peripheral populations so far. In this study we assess population structure and genetic variation among seven of these fringe populations using 105 polymorphic Amplified Fragment Length Polymorphism (AFLP) loci. We found a well-defined population structure without evidence for isolation by distance, implying restricted gene flow between populations. Additionally, the populations differed in their amount of genetic variation, emphasizing the need to monitor genetically impoverished populations for possible declines mediated by inbreeding depression and reduced adaptive potential. Conservation implications for these unique populations are discussed in the light of our results.
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29. |
- Rogell, Björn, 1979-
(author)
-
Genetic variation and local adaptation in peripheral populations of toads
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Northern fringe populations generally have low amounts of genetic variation and inhabit habitats where specific adaptations are needed. On the Swedish west coast, the natterjack toad (Bufo calamita) inhabits skerry islands. I have examined: I) adaptation to two environmental stressors in this habitat; II) the genetic population structure within the skerry habitat; III) the effects of neutral genetic variation, selection and genetic drift on trait divergence within the skerry habitat; and IV) the effects of genetic variation on fitness under three thermal conditions of varying stressfulness. V) I have also studied the impact of putative local adaptations on the Scandinavian green toad (Bufo viridis) conservation programme. The results suggest that the skerry natterjack toads are locally adapted to the desiccation risk in their habitat. However, despite inhabiting a more saline habitat, they had a lower salinity tolerance when compared to their conspecifics in the more general habitat. The lowered salinity tolerance is most likely explained by the presence of negative genetic correlations between salinity tolerance and desiccation avoidance and suggests that the occurrence of multiple environmental stressors may constrain adaptation. Within the skerry habitat, the toads exhibited a strong population structure with populations differing in their levels of genetic variation. Moreover, within the skerry habitat, the results suggest uniform selection pressures. However, correlations between trait values and neutral genetic variation suggest that inbreeding depression may affect trait values and thus potentially constrain adaptation. In the natterjack toad, fitness costs associated with lack of genetic variation were only present under benign conditions and not under more natural conditions. This suggests that environmental stress masks inbreeding depression in these traits under natural conditions. In the study regarding the Scandinavian green toads, I found that one population inhabiting a saline habitat had a higher salinity tolerance than other populations in less saline habitats. This suggests the presence of local adaptation, which should be acknowledged in the green toad conservation programme. Several of the northern fringe populations of toads fulfill the criteria of being Evolutionary Significant Units and their conservation thus should be prioritized.
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30. |
- Rogell, Björn, et al.
(author)
-
Pelagisk fisk i Mälaren 2022
- 2023
-
Reports (other academic/artistic)abstract
- Sötvattenslaboratoriet vid Institutionen för akvatiska resurser, SLU, genomförde hösten 2022 en hydroakustisk undersökning i fyra delområden av Mälaren. Studien genomfördes mellan 2022-09-26 och 2022-09-29, och är en del av årliga hydroakustiska undersökningar som utförs i Mälaren, Vänern och Vättern. De delområden som undersöktes var Ekoln, Granfjärden, Prästfjärden och Görväln. Det var möjligt att analysera åtta 8 arter inklusive kombinationer av art och åldersklass (nors 0+, nors >0+, siklöja 0+, siklöja >0+, storspigg, gös 0+, gös >0+ och braxen). Beståndstrender av årsyngel av siklöja och gös (0+) undersöktes genom förekomster i tråldrag. För de undersökta arterna var populationsutvecklingen över tid relativt likartad. Jämförelser gjordes mellan medelvärdet för de senaste två åren (2022 och 2021) med medelvärdet för en referensperiod, bestående av de fem föregående åren (2016 och 2020).• Norsbeståndet var generellt stabilt med god rekrytering.• Fortsatt god rekrytering av gös i Granfjärden.• Siklöjebeståndet är stabilt sedan 2012, med en relativt god rekrytering i Görväln.• Antalet stora fiskar (>17 cm) tenderar att minska i Ekoln.
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31. |
- Rogell, Björn, et al.
(author)
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Pelagisk fisk i Vättern 2022
- 2023
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Reports (other academic/artistic)abstract
- Sötvattenslaboratoriet vid Institutionen för akvatiska resurser, SLU, genomförde hösten 2022 hydroakustiska undersökningar med provtrålning i Vättern. Undersökningarna genomfördes mellan 2022-09-05 och 2022-09-14, och är ett i raden av de årliga hydroakustiska undersökningar som utförs i Mälaren, Vänern och Vättern. I undersökningen delades Vättern in i fyra delområden (Norra (N), Mellersta-Norra (MN), Mellersta-södra (MS) och Södra (S) Vättern). Resultat av analyserna 2022 omfattar 7 arter, inklusive kombinationer av art och åldersklass (nors 0+, nors >0+, sik, siklöja 0+, siklöja >0+ och storspigg). För att dra slutsatserom beståndens utveckling jämfördes medelvärdet för de senaste två åren (2022 och 2021), med medelvärdet för de föregående fem åren (2016-2020). Resultaten indikerade att antalet ekon från större fiskar (> 17 cm) ökat, att biomassan per hektar var relativt hög, samt att den starka rekryteringen av siklöja 2021 har gett upphov till en ökning av beståndet av siklöja 2022. Rådgivning till förvaltningen ges endast för siklöja och nors då övriga arter inte fångas i tillräckliga antal.• Siklöja hade en mycket stark rekrytering år 2021. För 2022 noterades en normalstark rekrytering. Antalet ettåriga och äldre siklöjor har börjat öka. Detta beror på måttliga till starka rekryteringar 2013, 2016, 2018, 2021 och nu även 2022, vilket är ovanligt frekvent för Vättern.• Siklöja utgjorde 2022 68 % av den totala biomassan i öppet vatten.• Sett till antal fiskar bestod det pelagiska fisksamhället i september till 73 % av små bytesfiskar (<81 mm), huvudsakligen årsyngel av nors. Antalet stora fiskar har dock ökat, och andelen potentiell bytesfisk relativt potentiella rovfiskar är lägre jämfört med tidigare år.• Norsbeståndet har varit relativt stabilt sedan 2015, och har haft god rekrytering under flera år.
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32. |
- Rogell, Björn, 1979-, et al.
(author)
-
Population divergence of life history traits in the endangered green toad : implications for a support release programme
- 2011
-
In: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 285:1, s. 46-55
-
Journal article (peer-reviewed)abstract
- There is an increasing awareness that adaptive differences among local populations may affect the success of translocation programmes. A mismatch in habitat quality of the target localities and in the local adaptations of the translocated individuals may reduce the success rate of the translocation programme. The green toad Bufo viridis is the most threatened amphibian in Sweden and has been the focus of an extensive translocation programme of eggs, tadpoles and juvenile toads to several localities with apparently favourable conditions for green toads. However, the success of these measures has been poor. In this study, we investigated the extent of local adaptation in the green toad by examining population divergence and the effect of thermal and saline conditions on larval performance in four Scandinavian populations. In a common garden experiment, we measured larval survival and development as well as the occurrence of spinal deformations. In addition, we quantified pond temperature and water salinity, two important environmental variables for larval performance in anurans in the breeding ponds as well as in seven additional localities included in the conservation programme. We found significant variation among the localities in water temperature and salinity, and significant among-population divergence in larval life history traits and spinal deformations, including both trait means and plastic responses to salinity and temperature. The available evidence suggests that at least part of this divergence is adaptive. We did not find direct support for local adaptation affecting the success of the translocations, however, we argue that the population origin and the impact of rearing conditions on the fitness-related larval traits should be taken into account in the introduction measures of the Swedish green toad conservation programme as well as in translocation programmes in general.
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33. |
- Rogell, Björn, et al.
(author)
-
Sambandet mellan fisketid och fångst i yrkesfisket efter signalkräfta i Vättern : en experimentell undersökning
- 2021
-
Reports (pop. science, debate, etc.)abstract
- Tidigare ramöverenskommelse mellan HaV och SLU (HaV dnr 1886-19)beslutades utökas 2021 genom att bl.a. genomföra ett försök tillsammansmed yrkesfiskarna inom projekt ”Datainsamling sötvattenskräftor” (projekt#29). Beställningen löd: ”Underlaget från fältförsöket med yrkesfiskarekommer att ligga till grund för hur SLU Aqua utvärderar årets provfiskenoch provtagningar för Vättern. En skriftlig årlig rapport kommer att skrivasunder början av 2022 och publiceras inom SLU Aquas granskade serieAqua reports.” Detta PM kommer att utgöra ett underlag för kommandeAqua report. Det utgör också ett viktigt dokument vid kommandeförändringar vid inrapportering av yrkesfiskets loggböcker gällandesignalkräfta samt vid SLU Aquas översyn av projekt ”datainsamlingkräftor”. Detta PM utgör leverans av beställt underlag.Dokumentet är framtaget av Björn Rogell tillsammans med Patrik Bohman(projektledare). För granskning och kvalitetssäkring har Martin Ogonowski ochAlfred Sandström bidragit. Alla inblandade personer är verksamma inom enhetenför stora sjöarna.
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34. |
- Rogell, Björn, et al.
(author)
-
Sex-dependent evolution of life-history traits following adaptation to climate warming
- 2014
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In: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 28:2, s. 469-478
-
Journal article (peer-reviewed)abstract
- SummaryThermodynamic processes increase metabolic rate and decrease longevity at high temperatures in ectotherms. However, how sustained long-term increase in temperature affects the evolution of longevity is poorly understood.Stress theory of ageing predicts that increased longevity is positively genetically correlated with resistance to different types of environmental stressors implying that evolutionary trajectories of ageing may be mediated by correlative selection for robust phenotypes under thermal stress.Here, we test this hypothesis by using replicate populations of the seed beetle Callosobruchus maculatus, evolving under two thermal environments: ancestral 30 °C and incremental increase towards novel 36 °C.Beetles evolving under climate warming became larger, more fecund and lived longer than the beetles evolving under 30 °C across both environments. However, the increase in longevity was partly due to parental effects because after two generations of acclimatization it persisted only in males.Our results support the hypothesis that evolution of stress resistance confers increased longevity through positive pleiotropy but demonstrate that such effects can be sex specific. These findings suggest that sex differences can evolve as correlated responses to selection under environmental change.
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35. |
- Rogell, Björn, et al.
(author)
-
Six polymorphic microsatellite loci in the Natterjack toad, Bufo calamita
- 2005
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In: Molecular Ecology Notes. - : Wiley. - 1471-8278 .- 1471-8286. ; 5:3, s. 639-640
-
Journal article (peer-reviewed)abstract
- The Natterjack toad, Bufo calamita, is a locally endangered anuran endemic to Europe. It has been used as a model organism in several ecological studies. When studying the genetic structure of marginalized populations of the species, there was a need to involve more loci in the study than those previously published. Here we present the development of six polymorphic microsatellite loci in the Natterjack. The loci will be used for studying population genetic structure and gene flow between populations.
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36. |
- Rogell, Björn, et al.
(author)
-
Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta
- 2012
-
In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 21:12, s. 2963-2976
-
Journal article (peer-reviewed)abstract
- There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A QST - FST approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in 1 year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. QST in body size did not differ between the rearing environments, and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system, constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a suboptimal management strategy for trout populations facing selection in the stream environment.
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37. |
- Rogell, Björn, 1979-, et al.
(author)
-
The effects of selection, drift and genetic variation on life-history trait divergence among insular populations of natterjack toad, Bufo calamita
- 2010
-
In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 19:11, s. 2229-2240
-
Journal article (peer-reviewed)abstract
- Although loss of genetic variation is frequently assumed to be associated with loss of adaptive potential, only few studies have examined adaptation in populations with little genetic variation. On the Swedish west coast, the northern fringe populations of the natterjack toad Bufo calamita inhabit an atypical habitat consisting of offshore rock islands. There are strong among-population differences in the amount of neutral genetic variation, making this system suitable for studies on mechanisms of trait divergence along a gradient of within-population genetic variation. In this study, we examined the mechanisms of population divergence using Q(ST)-F-ST comparisons and correlations between quantitative and neutral genetic variation. Our results suggest drift or weak stabilizing selection across the six populations included in this study, as indicated by low Q(ST)-F-ST values, lack of significant population x temperature interactions and lack of significant differences among the islands in breeding pond size. The six populations included in this study differed in both neutral and quantitative genetic variation. Also, the correlations between neutral and quantitative genetic variation tended to be positive, however, the relatively small number of populations prevents any strong conclusions based on these correlations. Contrary to the majority of Q(ST)-F-ST comparisons, our results suggest drift or weak stabilizing selection across the examined populations. Furthermore, the low heritability of fitness-related traits may limit evolutionary responses in some of the populations.
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38. |
- Rogell, Björn, 1979-, et al.
(author)
-
The interaction of multiple environmental stressors affects adaptation to a novel habitat in the natterjack toad Bufo calamita
- 2009
-
In: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 22:11, s. 2267-2277
-
Journal article (peer-reviewed)abstract
- The potential to adapt to novel environmental conditions is a key area of interest for evolutionary biology. However, the role of multiple selection pressures on adaptive responses has rarely been investigated in natural populations. In Sweden, the natterjack toad Bufo calamita inhabits two separate distribution areas, one in southernmost Sweden and one on the west coast. We characterized the larval habitat in terms of pond size and salinity in the two areas, and found that the breeding ponds of the western populations run higher desiccation risk and had higher salinity than the ponds used by the southern populations. In a common garden experiment manipulating salinity and temperature, we found that toads from the west coast populations were locally adapted to shorter pond duration as indicated by their higher development and growth rates. However, despite being subjected to higher salinity stress in nature, west coast toads had a poorer performance in saline treatments. We found that survival in the saline treatments in the west coast populations was positively affected by larger body mass and longer larval period. Furthermore, we found negative genetic correlations between body mass and growth rate and their non-adaptive plastic responses to salinity. These results implicate that the occurrence of multiple environmental stressors needs to be accounted for when assessing the adaptive potential of organisms and suggest that genetic correlations may play a role in constraining adaptation of natural populations.
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39. |
- Rowiński, Piotr K., et al.
(author)
-
Environmental stress correlates with increases in both genetic and residual variances : A meta-analysis of animal studies
- 2017
-
In: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 71:5, s. 1339-1351
-
Journal article (peer-reviewed)abstract
- Adaptive evolutionary responses are determined by the strength of selection and amount of genetic variation within traits, however, both are known to vary across environmental conditions. As selection is generally expected to be strongest under stressful conditions, understanding how the expression of genetic variation changes across stressful and benign environmental conditions is crucial for predicting the rate of adaptive change. Although theory generally predicts increased genetic variation under stress, previous syntheses of the field have found limited support for this notion. These studies have focused on heritability, which is dependent on other environmentally sensitive, but nongenetic, sources of variation. Here, we aim to complement these studies with a meta-analysis in which we examine changes in coefficient of variation (CV) in maternal, genetic, and residual variances across stressful and benign conditions. Confirming previous analyses, we did not find any clear direction in how heritability changes across stressful and benign conditions. However, when analyzing CV, we found higher genetic and residual variance under highly stressful conditions in life-history traits but not in morphological traits. Our findings are of broad significance to contemporary evolution suggesting that rapid evolutionary adaptive response may be mediated by increased evolutionary potential in stressed populations.
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40. |
- Rowiński, Piotr K., 1982-
(author)
-
Evolutionary consequences of maternal effects and stress
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Maternal effects occur when maternal environment or phenotype influence offspring phenotype, in addition to genetic contribution of the mother. As maternal effects often influence phenotypes that are under natural selection, they hence have evolutionary consequences. Further, the expression of both maternal effects and evolutionary potential has been argued to depend on environmental conditions, but the evidence of this dependency for the process of adaptation has been inconclusive. The main objective of this thesis was to investigate evolutionary consequences of maternal effects and stressful or variable environmental conditions.I started by performing a meta-analysis of quantitative genetic studies that investigated expression of additive genetic, maternal, and residual variance under both stressful and benign environmental conditions (Paper I). Data spanning over many animal taxa and stress types revealed that high levels of environmental stress correlated with increased expression of genetic and residual variances. However, against our predictions, maternal effects were relatively unaffected by stress.In Paper II and III, I explored the evolutionary divergences of traits previously shown to be under maternal control. Specifically, in Paper II, I performed a second meta-analysis, that investigated if parents of common frogs (Rana temporaria) influenced offspring development time to mediate the effects of time constraints, across a latitudinal cline. I found that reproductive delay in the parental generation correlated with decreased development time in tadpoles of northern R. temporaria populations, suggesting that parental effects may further decrease development time in populations from time-constrained environments.In Paper III, I used an annual killifish system, to explore if environmental unpredictability, measured by variation in precipitation during rainy season, correlated with maternally mediated variation in embryo development time (bet-hedging). Although I found significant among-species differences in variation in development time, there was no clear linear relationship between variation in development time and precipitation. The results suggest that either bet-hedging is not important for persistence in the unpredictable annual killifish habitats, or that other ecological factors, rather than precipitation unpredictability, influenced evolution of variation in development times.Lastly, I investigated if occurrence of placenta correlated with increased offspring brain size among poeciliid fish (Paper IV). In contrast to our prediction, I did not find any consistent differences in relative brain size between the fry of placental and non-placental species. It is possible that either the poeciliid placental structures do not have a sufficient capacity to transfer resources necessary for increased brain development, or that other factors, such as sexual selection, or differences in food abundance and competition, shaped brain evolution among poeciliids.In conclusion, the results of this thesis suggest that environmental stress may influence evolutionary potential by increasing genetic variation available for selection, that time-constrained habitats may be conducive to evolution of parental effects on offspring development times, and that maternal influence on offspring traits may be difficult to detect, as many ecological factors may potentially influence evolution of life-history and morphology traits.
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41. |
- Rowiński, Piotr K., et al.
(author)
-
Parental effects influence life history traits and covary with an environmental cline in common frog populations
- 2020
-
In: Oecologia. - : Springer Nature. - 0029-8549 .- 1432-1939. ; 192:4, s. 1013-1022
-
Journal article (peer-reviewed)abstract
- Across latitudinal clines, the juvenile developmental rates of ectotherms often covary with the length of the growing season, due to life-history trade-offs imposed by the time-constrained environments. However, as the start of the growing season often varies substantially across years, adaptive parental effects on juvenile developmental rates may mediate the costs of a delayed season. By employing a meta-analysis, we tested whether larval developmental rates across a latitudinal cline of the common frog (Rana temporaria) are affected by fluctuating onsets of breeding, across years. We predicted that larval developmental rate will be inversely related to the onset of breeding, and that northern populations will be more prone to shorten their developmental rate in response to late breeding, as the costs of delayed metamorphosis should be highest in areas with a shorter growing season. We found that the larval period of both northern and southern populations responded to parental environmental conditions to a similar degree in absolute terms, but in different directions. In northern populations, a late season start correlated with decreased development time, suggesting that the evolution of parental effects aids population persistence in time-constrained environments. In southern populations, late season start correlated with increased development time, which could potentially be explained as a predator avoidance strategy. Our findings suggest that local ecological variables can induce adaptive parental effects, but responses are complex, and likely trade-off with other ecological factors.
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42. |
- Rowiński, Piotr K., et al.
(author)
-
Variation in developmental rates is not linked to environmental unpredictability in annual killifishes
- 2021
-
In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11:12, s. 8027-8037
-
Journal article (peer-reviewed)abstract
- Comparative evidence suggests that adaptive plasticity may evolve as a response to predictable environmental variation. However, less attention has been placed on unpredictable environmental variation, which is considered to affect evolutionary trajectories by increasing phenotypic variation (or bet hedging). Here, we examine the occurrence of bet hedging in egg developmental rates in seven species of annual killifish that originate from a gradient of variation in precipitation rates, under three treatment incubation temperatures (21, 23, and 25°C). In the wild, these species survive regular and seasonal habitat desiccation, as dormant eggs buried in the soil. At the onset of the rainy season, embryos must be sufficiently developed in order to hatch and complete their life cycle. We found substantial differences among species in both the mean and variation of egg development rates, as well as species-specific plastic responses to incubation temperature. Yet, there was no clear relationship between variation in egg development time and variation in precipitation rate (environmental predictability). The exact cause of these differences therefore remains enigmatic, possibly depending on differences in other natural environmental conditions in addition to precipitation predictability. Hence, if species-specific variances are adaptive, the relationship between development and variation in precipitation is complex and does not diverge in accordance with simple linear relationships.
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43. |
- Rowiński, Piotr, 1982-, et al.
(author)
-
The evolution of a placenta is not linked to increased brain size in poeciliid fishes
-
Other publication (other academic/artistic)abstract
- Maternal investment traits are considered to have a direct influence on the size of energetically costly organs, including the brain. In placental organisms, offspring are supplied with nutrients during pre-natal development, which in turn may modulate brain size evolution. While this hypothesis has received some support in mammals (i.e. in the marsupial/placental transition), how the evolution of the placenta affects brain size in other taxa is largely unknown.Here, we use eight poeciliid fish species to test if species with placental transferred nutrients, invest more resources into offspring brain development than species with no placental structures. We predicted that the evolution of the placenta would be associated with larger relative brain size in fry, and possibly also shallower ontogenetic brain size allometry, if cognitive demands are similar in adults across placental and non-placental species. We tested these hypotheses by taking non-invasive brain size measurements during the first four weeks of life, and relating these to corresponding somatic growth. Contrary to our expectations, we did not find any differences in brain size between the two maternal strategies. Furthermore, we did not find any differences in how relative brain size changed over ontogenetic development between placental and non-placental species. Elsewhere, maternal investment traits have been commonly linked to brain size, however the species investigated here only exhibit pre-natal provisioning, which may reduce the potential for maternal investment into brain size. Our results suggest that coevolution between placental structures and juvenile brain size is not a general pattern.
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44. |
- Rowiński, Piotr, 1982-, et al.
(author)
-
Thermally induced parental effects influence life history traits and covary with an environmental cline in common frog populations
-
Other publication (other academic/artistic)abstract
- Across latitudinal clines, the juvenile developmental rates of ectotherms often covary with the length of the growing season, due to life-history trade-offs imposed by time-constrained environments. However, as the start of the growing season often varies substantially across years, adaptive parental effects on juvenile developmental rates may mediate the costs of a delayed spring. By employing a meta-analysis, we tested whether larval developmental rates across a latitudinal cline of common frogs (Rana temporaria) are affected by fluctuating onsets of breeding, across years. We predicted that larval developmental rate will be inversely related to the onset of breeding, and that northern populations will be more prone to shorten their developmental rate in response to late breeding, as the costs of delayed metamorphosis should be highest in areas with a shorter growing season. We found that the larval period of both northern and southern populations responded to parental environmental conditions to similar degree in absolute terms, but in different directions. In northern populations, a late season start correlated with decreased development time, suggesting that the evolution of parental effects aid population persistence in time-constrained environments. In southern populations, late season start correlated with increased development time, which could potentially be explained as a predator avoidance strategy. Our findings suggest that local ecological variables can induce adaptive parental effects, but responses are complex, and likely trade-off with other ecological factors.
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45. |
- Rowiński, Piotr, 1982-, et al.
(author)
-
Variation in developmental rates is not linked to environmental unpredictability in annual killifishes
-
Other publication (other academic/artistic)abstract
- Comparative evidence suggests that adaptive plasticity may evolve as a response to predictable environmental variation. However, receiving less attention is unpredictable environmental variation, which is considered to affect evolutionary trajectories by increasing phenotypic variation (bet-hedging). If increased variance in development time evolved as an adaptation to unpredictable environmental conditions, we would expect species inhabiting locations with unpredictable conditions to have a higher variance in development time. Here, we examine the occurrence of bet-hedging in egg developmental rate in seven species of annual killifish, originating from a gradient of precipitation rate variation, under three different incubation temperatures (21°C, 23°C, and 25°C). These fish species persist as dormant eggs buried in the soil, in seasonal environments with regular habitat desiccation. At the onset of the rainy season, the eggs must be sufficiently developed in order to hatch, and complete their life-cycle. We found substantial differences among species in both mean and variation of egg development rates, as well as species-specific plastic temperature responses. However, there was no clear relationship between variation in egg development time and variation in precipitation (environmental predictability). Hence, if species specific variances are adaptive, they do not diverge in accordance with simple linear relationship to variation in precipitation.
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46. |
- Rudh, Andreas, et al.
(author)
-
Non-gradual variation in colour morphs of the strawberry poison frog Dendrobates pumilio : genetic and geographical isolation suggest a role for selection in maintaining polymorphism
- 2007
-
In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 16:20, s. 4284-4294
-
Journal article (peer-reviewed)abstract
- The relative roles that geographical isolation and selection play in driving population divergence remain one of the central questions in evolutionary biology. We approached this question by investigating genetic and morphological variation among populations of the strawberry poison frog, Dendrobates pumilio, in the Bocas del Toro archipelago, Panama. We found significant population genetic structure and isolation by distance based on amplified fragment length polymorphism markers. Snout vent length (SVL), coloration and the extent and size of dorsal black spots showed large variation among the studied populations. Differences in SVL correlated with genetic distance, whereas black spot patterns and other coloration parameters did not. Indeed, the latter characters were observed to be dramatically different between contiguous populations located on the same island. These results imply that neutral divergence among populations may account for the genetic patterns based on amplified fragment length polymorphism markers and SVL. However, selective pressures need to be invoked in order to explain the extraordinary variation in spot size and coverage, and coloration. We discuss the possibility that the observed variation in colour morphs is a consequence of a combination of local variation in both natural selection on an aposematic signal towards visual predators and sexual selection generated by colour morph-specific mate preferences.
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47. |
- Rudh, Andreas, et al.
(author)
-
Rapid population divergence linked with co-variation between coloration and sexual display in strawberry poison frogs
- 2011
-
In: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 65:5, s. 1271-1282
-
Journal article (peer-reviewed)abstract
- The likelihood of speciation is assumed to increase when sexually selected traits diverge together with ecologically important traits. According to sexual selection theory, the evolution of exaggerated display behavior is driven by increased mating success, but limited by natural selection, for example, through predation. However, the evolution of aposematic coloration (i.e., an ecologically important trait) could relieve the evolution of exaggerated display behavior from the bound of predation, resulting in joint divergence in aposematic coloration and sexual display behavior between populations. We tested this idea by examining conspicuousness, using color contrasts between individuals and their native backgrounds, and sexual display of 118 males from genetically diverged populations of the Strawberry poison frog, Dendrobates pumilio. Our results show that the level of conspicuousness of the population predicts the sexual display behavior of males. Males from conspicuous populations used more exposed calling sites. We argue that changes in aposematic coloration may rapidly cause not only postmating isolation due to poorly adapted hybrids, but also premating isolation through shifts in mating behaviors.
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48. |
- Sowersby, Will, et al.
(author)
-
Costly sexual ornaments coevolve with fast life-histories in killifishes
-
Other publication (other academic/artistic)abstract
- Sexually selected ornaments constitute an important investment into reproduction, increasing current mating success, at a potential cost to survival. Theory suggests that exaggerated sexual ornaments may coevolve with the life-history trade-off between current and future reproduction, however this hypothesis has remained unexplored. Here, we determine how the size of secondary sexual traits coevolves with the pace of life-histories (slow or fast), using a clade of killifishes, where independent adaptations to ephemeral environments have resulted in substantial divergences in life-history strategy. In addition, we assess costs to swimming performance driven by enlarged, ornamental fins. We predict that killifishes with fast life-histories, which inhabit time-limited environments and prioritize current reproduction, will have a greater tendency to evolve enlarged fins, compared to killifishes with slow life-histories. Indeed, we found that species with fast life-histories had more pronounced sexual size dimorphism, with males from these species having exaggerated dorsal and anal fins, compared to species with slow life-histories. Furthermore, males from species with fast life-histories and larger ornaments exhibited lower swimming performances compared to both conspecific females, and individuals from species with slow life-histories. Our results indicate that the trade-off between current and future reproduction, can be an evolutionary driver of costly sexual ornaments.
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49. |
- Sowersby, Will, et al.
(author)
-
Fast life-histories are associated with larger brain size in killifishes
- 2021
-
In: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:9, s. 2286-2298
-
Journal article (peer-reviewed)abstract
- The high energetic demands associated with the vertebrate brain are proposed to result in a trade-off between the pace of life-history and relative brain size. However, because both life-history and brain size also have a strong relationship with body size, any associations between the pace of life-history and relative brain size may be confounded by coevolution with body size. Studies on systems where contrasts in the pace of life-history occur without concordant contrasts in body size could therefore add to our understanding of the potential coevolution between relative brain size and life-history. Using one such system - 21 species of killifish - we employed a common garden design across two ontogenetic stages to investigate the association between relative brain size and the pace of life-history. Contrary to predictions, we found that relative brain size was larger in adult fast-living killifishes, compared to slow-living species. Although we found no differences in relative brain size between juvenile killifishes. Our results suggest that fast- and slow-living killifishes do not exhibit the predicted trade-off between brain size and life-history. Instead, fast and slow-living killifishes could differ in the ontogenetic timing of somatic versus neural growth or inhabit environments that differ considerably in cognitive demands.
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50. |
- Sowersby, Will, et al.
(author)
-
Sex ratios deviate across killifish species without clear links to life history
- 2020
-
In: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 34:3, s. 411-426
-
Journal article (peer-reviewed)abstract
- Sex ratios can differ from an expected equal proportion of males and females, carrying substantial implications for our understanding of how mating systems evolve. Typically, macro-evolutionary studies have been conducted without assessing how deviations from an equal sex ratio could be explained by sex-biased mortality or dispersal. Our understanding of sex ratio evolution independent of these confounds, in addition to any putative links between skewed sex ratios and other factors (e.g. life history), therefore remains largely unexplored. Here, we conducted an exploratory study investigating differences in sex ratios across closely related species while controlling for extrinsic mortality. We also tested two factors, non-overlapping/overlapping generations and the social environment, which have both been hypothesised to affect sex ratios. Specifically, we raised 15 species of killifish, which have either overlapping or discrete generations, under both solitary and social treatments. We found substantial divergences in sex ratios across closely related species, which exhibited both male and female biases. In conjunction with a low phylogenetic signal, our results suggest that sex ratios can evolve rapidly in this group. However, we found no evidence that overlapping generations or the social environment affected sex biases, suggesting that other factors drive the rapid evolution of sex ratios in killifishes.
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