| 1. |
- Abbott, Jessica, et al.
(författare)
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Ontogeny of sexual dimorphism and phenotypic integration in heritable morphs
- 2008
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 22:1, s. 103-121
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigated the developmental basis of adult phenotypes in a non-model organism, a polymorphic damselfly (Ischnura elegans) with three female colour morphs. This polymorphic species presents an ideal opportunity to study intraspecific variation in growth trajectories, morphological variation in size and shape during the course of ontogeny, and to relate these juvenile differences to the phenotypic differences of the discrete adult phenotypes; the two sexes and the three female morphs. We raised larvae of different families in individual enclosures in the laboratory, and traced morphological changes during the course of ontogeny. We used principal components analysis to examine the effects of Sex, Maternal morph, and Own morph on body size and body shape. We also investigated the larval fitness consequences of variation in size and shape by relating these factors to emergence success. Females grew faster than males and were larger as adults, and there was sexual dimorphism in body shape in both larval and adult stages. There were also significant effects of both maternal morph and own morph on growth rate and body shape in the larval stage. There were significant differences in body shape, but not body size, between the adult female morphs, indicating phenotypic integration between colour, melanin patterning, and body shape. Individuals that emerged successfully grew faster and had different body shape in the larval stage, indicating internal (non-ecological) selection on larval morphology. Overall, morphological differences between individuals at the larval stage carried over to the adult stage. Thus, selection in the larval stage can potentially result in correlated responses in adult phenotypes and vice versa.
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| 2. |
- Arct, Aneta, et al.
(författare)
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Heterozygosity-fitness correlations in blue tit nestlings (Cyanistis caeruleus) under contrasting rearing conditions
- 2017
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Ingår i: Evolutionary Ecology. - : SPRINGER. - 0269-7653 .- 1573-8477. ; 31:5, s. 803-814
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the relation between genetic variation and fitness remains a key question in evolutionary biology. Although heterozygosity has been reported to correlate with many fitness-related traits, the strength of the heterozygosity-fitness correlations (HFCs) is usually weak and it is still difficult to assess the generality of these associations in natural populations. It has been suggested that HFCs may become meaningful only under particular environmental conditions. Moreover, existing evidence suggests that HFCs may also differ between sexes. The aim of this study was to investigate correlations between heterozygosity in neutral markers (microsatellites) and fitness-related traits in a natural population of blue tits (Cyanistes caeruleus). Additionally, we tested whether sex and environmental conditions may influence the magnitude and direction of HFCs. We found a positive relationship between heterozygosity and body mass of 14 days post-hatching nestlings, but only among females. Our results suggest that the correlation between heterozygosity and nestling body mass observed among female offspring could be attributed to within-brood effects. We failed to find any evidence that environmental conditions as simulated by brood size manipulation affect HFCs.
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| 3. |
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| 4. |
- Berdan, Emma L, 1983, et al.
(författare)
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Inversion frequencies and phenotypic effects are modulated by the environment: insights from a reciprocal transplant study in Coelopa frigida
- 2018
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 32:6, s. 683-698
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how environmental variation drives phenotypic diversification within species is a major objective in evolutionary biology. The seaweed fly Coelopa frigida provides an excellent model for the study of genetically driven phenotypes because it carries an / inversion polymorphism that affects body size. Coelopa frigida inhabits highly variable beds of decomposing seaweed on the coast in Scandinavia thus providing a suitable test ground to investigate the genetic effects of substrate on both the frequency of the inversion (directional selection) and on the phenotype (genotypexenvironment effects). Here we use a reciprocal transplant experiment to test the effect of the / inversion on body size traits and development time across four suitable natural breeding substrates from the clinal distribution. We show that while development time is unaffected by GxE effects, both the frequency of the inversion and the relative phenotypic effects of the inversion on body size differ between populationxsubstrate combinations. This indicates that the environment modulates the fitness as well as the phenotypic effects of the inversion karyotypes. It further suggests that the inversion may have accumulated qualitatively different mutations in different populations that interact with the environment. Together our results are consistent with the idea that the inversion in C. frigida likely evolves via a combination of local mutation, GxE effects, and differential fitness of inversion karyotypes in heterogeneous environments.
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| 5. |
- Berger, David, et al.
(författare)
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What keeps insects small? - Size dependent predation on two species of butterfly larvae
- 2006
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 20:6, s. 575-589
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Tidskriftsartikel (refereegranskat)abstract
- Insect size usually increases greatly in the latter stages of development, while reproductive value increases strongly with adult size. Mechanisms that can balance the benefits associated with increased growth are poorly understood, raising the question: what keeps insects from becoming larger? If predation risk was to increase with juvenile size, it would make an extension of development very risky, favouring smaller final sizes. But field measures of juvenile mortality seldom show any general patterns of size dependence. We here therefore try to estimate a mechanistic relationship between juvenile size and predation risk by exposing the larvae of two closely related butterflies to a generalist invertebrate predator in a laboratory experiment. Predation risk increased with larval size but was not affected by the species-specific growth rate differences. These results indicate that predation risk may increase with the size of the juvenile even when predators are relatively small. By basing a model simulation on our data we also show that size dependent predation of the kind found in this study has potential to stabilise selection on body size in these species. Thus, these findings suggest that more detailed studies of the size dependence of predation risk on juvenile instars will increase the understanding of what it is that keeps insects small.
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| 6. |
- Berglund, Anders
(författare)
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To change or not to change sex : A comparison between two Ophryotrocha species (Polychaeta)
- 1991
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Ingår i: Evolutionary Ecology. - 0269-7653 .- 1573-8477. ; 5:2, s. 128-135
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Tidskriftsartikel (refereegranskat)abstract
- The polychaete Ophryotrocha puerilis is a male-to-female sex-changer, whereas O. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in some O. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that in O. puerilis males should not benefit reproductively from a size increase as much as males in O. labronica: hence O. puerilis but not O. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundity per se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. In O. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas in O. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained in O. puerilis, and why separate sexes are maintained in O. labronica.
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| 7. |
- Bjorklund, M
(författare)
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The importance of evolutionary constraints in ecological time scales
- 1996
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Ingår i: EVOLUTIONARY ECOLOGY. - : CHAPMAN HALL LTD. - 0269-7653. ; 10:4, s. 423-431
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The importance of constraints, defined as factors that retard or prevent a population from reaching its immediate adaptive peak on an ecological time scale is analysed. This is done by means of simple quantitative genetic models, which if anything underes
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| 8. |
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| 9. |
- Boalt, Elin, et al.
(författare)
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The association among herbivory tolerance, ploidy level, and herbivory pressure in cardamine pratensis
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:5, s. 1101-1113
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Tidskriftsartikel (refereegranskat)abstract
- We tested whether differences in ploidy level and previous exposure to herbivory can affect plant tolerance to herbivory. We conducted a common garden experiment with 12 populations of two ploidy levels of the perennial herb Cardamine pratensis (five populations of tetraploid ssp. pratensis and seven populations of octoploid ssp. paludosa). Earlier studies have shown that attack rates by the main herbivore, the orange tip butterfly Anthocharis cardamines, are lower in populations of octoploids than in populations of tetraploids, and vary among populations. In the common garden experiment, a combination of natural and artificial damage significantly reduced seed and flower production. We measured tolerance based on four plant-performance metrics: survival, growth, seed production and clonal reproduction. For three of these measurements, tolerance of damage did not differ between ploidy levels. For clonal reproduction, the octoploids had a higher tolerance than the tetraploids, although they experience lower herbivore attack rates in natural populations. Populations from sites with high levels of herbivory had higher tolerance, measured by seed production, than populations with low levels of herbivory. We did not detect any significant costs of tolerance. We conclude that high intensity of herbivory has selected for high tolerance measured by seed production in C. pratensis.
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| 10. |
- Brodin, Anders, et al.
(författare)
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Hybrid zone maintenance by non-adaptive mate choice
- 2009
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 23:1, s. 17-29
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Tidskriftsartikel (refereegranskat)abstract
- In a spatial simulation we show that formation of a stable, narrow hybrid zone requires no selection, only that individuals can recognize their own population type since this is a prerequisite for assortative mating. The European crow occurs in two species/subspecies that meet in a long hybrid zone, the black carrion crow Corvus corone and the grey and black hooded crow C. cornix. In a previous study (Brodin A, Haas F (2006) Anim Behav 72:139) we mimicked sexual imprinting in nestling crows with artificial neural networks, using a learning process that simulates proximate retina perception. The networks were trained on 700 images to recognize either carrion, hooded or hybrid phenotypes as their own. After training the networks were exposed to 300 new, unfamiliar pictures of crows. The networks that had been trained on pure subspecies then showed strong preference for their own type. Networks trained on hybrid crows showed weaker preference for their own type. Assuming that these preferences will determine mate choice preferences we have combined them with empirical data on dispersal of young crows to investigate what kind of geographical distribution pattern this would create. We then assume that the two subspecies meet and hybridize along a straight border. In only 60 generations a stable, narrow hybrid zone that resembles the real hybrid zone was formed. This zone remained stable over time. With minor adjustments of parameters the results would not only fit the width but also the shapes of the clines in the field.
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| 11. |
- Broggi, Juli, et al.
(författare)
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Idle slow as you grow old: longitudinal age-related metabolic decline in a wild passerine
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 24:1, s. 177-184
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Tidskriftsartikel (refereegranskat)abstract
- Physiological changes due to aging are intensively studied as they have far-reaching implications for the mechanistic and evolutionary theories of senescence. In this respect, metabolic rate has been suggested to play a role for the deterioration and damage of cells and tissues with age, partly due to the generation of reactive oxygen species. To mitigate such damage, individuals can be predicted to reduce basal metabolic rate (BMR) with age. This prediction has been verified in humans and some laboratory animals but never in wild animal populations. We analyzed the change in BMR within individuals across years in two wild populations of great tit (Parus major) differing in BMR. Great tits, living under stressful conditions towards the northern limit of their distribution, decreased their BMR as they aged whereas no such decrease was found in a southern population. Thus, we found a clear decline only in the population with the highest BMR levels. This study provides the first evidence of an age-related decline in BMR for a wild homeotherm.
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| 12. |
- Chakarov, Nayden, et al.
(författare)
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Immune responses link parasite genetic diversity, prevalence and plumage morphs in common buzzards
- 2017
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 31:1, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- The evolution and maintenance of conspicuous phenotypic polymorphisms has challenged evolutionary ecologists for centuries. Polymorphisms in pleiotropic cascades or genetic linkage may lead to correlations of life history traits such as immunity, parasite infection levels, pigmentation and lifetime reproductive success. The common buzzard Buteo buteo is a bird of prey occurring in several plumage morphs, which differ in pigmentation and in the prevalence, infection intensity and clone composition of their most common blood parasite, as well as in ectoparasite infestation levels. Buzzard morphs are heritable and exhibit a heterozygote advantage where intermediates have higher lifetime reproductive success (LRS). We explored the hypothesis that the differences in pigmentation also correspond to differences in immunity. We hence compared an inducible adaptive and an innate constitutive immune response between the buzzard plumage morphs. The increase of specific anti-tetanus antibodies after vaccination was explained by the morph of the nestling’s mother and was highest in offspring of intermediate mothers. Additionally, nestlings with higher humoral response were less infected with blood parasites and, if infected, harboured a lower genetic diversity of these parasites. The phytohaemagglutinin-induced skin swelling, a complex of cellular inflammatory responses, was lowest in intermediate nestlings. The higher LRS of intermediate buzzards suggests that the cellular immunity is an inferior fitness determinant compared to humoral immunity. The strength of immune responses was not linear along the melanisation gradient, indicating that there is most likely no simple genetic correlation between immune responses and plumage morphs.
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| 13. |
- Ellmer, Maarten, et al.
(författare)
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The structuring of quantitative genetic variation in a fragmented population of Briza media (Poaceae)
- 2011
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 25:2, s. 509-523
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Tidskriftsartikel (refereegranskat)abstract
- The structuring of quantitative genetic variation can have a significant impact on the adaptive potential and long-term viability of species in changing landscapes. The present study of the grass Briza media investigated the relationships between patterns of heritable variation in phenotypic characters and descriptors of landscape structure, land-use history and local habitat conditions in a landscape known to have undergone a progressive and massive loss of semi-natural grassland habitat over the past 300 years. Our analyses revealed significant levels of heritable variation for characters related to overall plant size and spikelet size-number ratio, with estimates of broad-sense heritability ranging between 29 and 34%. Differences between demes accounted for a minor fraction of the total variation. In contrast to previous allozyme results from the same plant material, which suggest significant impacts of both neutral and selective processes, neither the deme-specific means nor the heritabilities for the phenotypic characters were consistently associated with landscape structure or land-use history. The results of the study indicate that the structuring of quantitative variation has been relatively insensitive to habitat fragmentation, at least over the time frame considered in this study system.
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| 14. |
- Erlandsson, Johan, et al.
(författare)
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Migratory differences between ecotypes of the snail Littorina saxatilis on Galician rocky shores
- 1998
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Ingår i: Evolutionary Ecology. - 0269-7653. ; 12:8, s. 913-924
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Tidskriftsartikel (refereegranskat)abstract
- Local migration patterns may be crucial to gene flow in species of marine gastropods which do not broadcast pelagic larvae. In some species, dispersal over distances of a few metres may influence micro-scale population structures. We investigated the migration pattern in Galician populations of the snail Littorina saxatilis in which populations of contrasting morphologies occupy different tidal levels of the same rocky shore. Two distinct morphs, one at the upper and one at the lower shore, overlap in distribution in a small mid-shore region where hybrids are produced. We documented the distances and directions of migration of both parental morphs and hybrids 1 month after they had been marked and released at different shore levels. When placed at their native shore level, snails migrated less than about 2 m and usually in independent directions. This supports the suggestion of a low local gene flow. At an alien shore level, however, the morphs often moved further and more directionally compared with native morphs. These differences may help to keep the two morphs separated at different shore levels. As fitness of an individual is highest in its native habitat, this seems to be an adaptive strategy.
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| 15. |
- Esperk, Toomas, et al.
(författare)
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Distinguishing between anticipatory and responsive plasticity in a seasonally polyphenic butterfly
- 2013
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 27:2, s. 315-332
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Tidskriftsartikel (refereegranskat)abstract
- Seasonal generations of short-lived organisms often differ in their morphological, behavioural and life history traits, including body size. These differences may be either due to immediate effects of seasonally variable environment on organisms (responsive plasticity) or rely on presumably adaptive responses of organisms to cues signalizing forthcoming seasonal changes (anticipatory plasticity). When directly developing individuals of insects are larger than their overwintering conspecifics, the between-generation differences are typically ascribed to responsive plasticity in larval growth. We tested this hypothesis using the papilionid butterly Iphiclides podalirius as a model species. In laboratory experiments, we demonstrated that seasonal differences in food quality could not explain the observed size difference. Similarly, the size differences are not likely to be explained by the immediate effects of ambient temperature and photoperiod on larval growth. The qualitative pattern of natural size differences between the directly developing and diapausing butterflies could be reproduced in the laboratory as a response to photoperiod, indicating anticipatory character of the response. Directly developing and diapausing individuals followed an identical growth trajectory until the end of the last larval instar, with size differences appearing just a few days before pupation. Taken together, various lines of evidence suggest that between-generation size differences in I. podalirius are not caused by immediate effects of environmental factors on larval growth. Instead, these differences rather represent anticipatory plasticity and are thus likely to have an adaptive explanation. It remains currently unclear, whether the seasonal differences in adult size per se are adaptive, or if they constitute co-product of processes related to the diapause. Our study shows that it may be feasible to distinguish between different types of plasticity on the basis of empirical data even if fitness cannot be directly measured, and contributes to the emerging view about the predominantly adaptive nature of seasonal polyphenisms in insects.
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| 16. |
- Forsman, A, et al.
(författare)
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Fearful symmetry: pattern size and asymmetry affects aposematic signal efficacy
- 1999
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Ingår i: EVOLUTIONARY ECOLOGY. - : KLUWER ACADEMIC PUBL. - 0269-7653. ; 13:2, s. 131-140
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Tidskriftsartikel (refereegranskat)abstract
- Aposematic animals use anti-predator defence mechanisms such as distastefulness coupled with distinctive odours, sounds, or colour patterns to signal their unprofitability to potential predators. By subjecting artificial 'butterflies' with different visua
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| 17. |
- Forsman, Anders
(författare)
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Rethinking the thermal melanism hypothesis: rearing temperature and coloration in pygmy grasshoppers
- 2011
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 25:6, s. 1247-1257
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Tidskriftsartikel (refereegranskat)abstract
- Selection for efficient conversion of solar radiation to body heat has favored theevolution of dark coloration in many ectotherms. The thermal melanism hypothesis positsthat dark coloration is beneficial under conditions of low ambient temperatures because itresults in faster heating rates and higher body temperatures. Fast heating rates, however,may come at a cost of overheating unless compensated for by thermal physiology orbehaviour. Pygmy grasshopper (Orthoptera, Tetrigidae) populations that inhabit fire-ravagedareas characterized by blackened backgrounds and hot surface temperatures due tohigh absorbance of solar radiation show an increased frequency of black phenotypes. Iraised the progeny of wild-captured Tetrix undulata in cold and hot temperatures and useddata on color patterns and survival in a greenhouse to examine whether a cold thermalenvironment triggered the development of melanic coloration or differently affected survivalof melanic versus non-melanic individuals. My results indicate that melanism was notinfluenced by rearing temperature but by genes or epigenetic maternal effects. Temperaturealso did not affect survival. However, melanic individuals produced by melanic motherssurvived longer than melanic individuals produced by non- melanic mothers, whereas nonmelanicindividuals produced by non-black mothers survived longer than melanic individualsproduced by non-black mothers. This suggests a mismatch between color andphysiology in offspring belonging to a different color morph than their mother. Futureinvestigations into the evolution of melanism should consider conflicting selection pressureson thermal capacity and camouflage as well as the influence of correlated responsesto selection on traits associated with coloration.
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| 18. |
- Friberg, Magne, et al.
(författare)
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Divergence in selection of host species and plant parts among populations of a phytophagous insect
- 2016
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 30:4, s. 723-737
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Tidskriftsartikel (refereegranskat)abstract
- The diversification of phytophagous insects is often attributed to diverging processes of host plant specialization onto different, often closely related, host plants. Some insect clades have diversified by specializing not only on different plant species but also on different plant parts of the same hosts. This is the case in Greya moths (Prodoxidae) where both Greya obscura and G. politella are tightly linked to host plants of the genus Lithophragma (Saxifragaceae). We assess how these species differ in their choice of plants and use of plant parts. Previous work showed that strong local host specialization in G. politella is mediated by floral scent variation among Lithophragma species. Here, we identify geographic variation in host plant use in the close relative G. obscura, relate the emerging patterns to previous studies of geographic variation in host use in G. politella and evaluate potential processes underlying the variation among and within species. First, we show that G. obscura also uses floral chemistry to locate hosts but that additional plant cues must be involved in deciding whether to oviposit on a plant, because females did not discriminate against chemically different host species in no-choice trials. We also found that, although all known populations of G. politella oviposit only in flowers, all G. obscura populations examined here distributed their eggs among both floral and scape tissues both in the field and in laboratory experiments. The distribution of eggs among plant parts, however, varied among moth populations, and also depended on the Lithophragma species they attacked. Together, these results show the potential for phytophagous insect species and populations to diverge in use of plant parts as part of the process of speciation and adaptation. These two layers of specialization enhance the potential for subsequent diversification in phytophagous insect lineages.
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| 19. |
- Friberg, Magne, et al.
(författare)
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Niche separation in space and time between two sympatric sister species—a case of ecological pleiotropy
- 2008
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477.
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Tidskriftsartikel (refereegranskat)abstract
- Abstract We investigate the niche separation in space and time between the Palearctic sister species Leptidea sinapis and L. reali (Lepidoptera, Pieridae) in central Sweden. Using field sampling, we show that L. reali is a habitat specialist confined to meadows, whereas L. sinapis is a habitat generalist also inhabiting forests. This difference in habitat utilization was corroborated by experimental release of laboratory-reared L. sinapis and L. reali in two adjacent forest and meadow habitats during their natural flight period; virtually all recaptured L. reali that were released in the forest were later caught in the meadow, whereas L. sinapis shifted equally often from meadow to forest as in the opposite direction. In the field, both species fly in May–June, but L. reali appears on average a week earlier in spring and has a substantial second generation in July, whereas L. sinapis is practically univoltine. When overwintered pupae were incubated under identical conditions in the laboratory, females did, however, not differ in phenology, and L. sinapis males actually emerged earlier than L. reali males. When larvae were reared at 23°C on the host plant Lotus corniculatus at a range of daylengths, both species produced a substantial proportion of directly developing individuals at an 18.5 h daylength or longer. When reared at 23°C and a 22 h daylength, L. reali showed an overall higher propensity to develop directly than L. sinapis on plant species originating from both the meadow and the forest habitat. Both Leptidea species showed a lower propensity to enter direct development on forest associated plants than on meadow associated plants. Hence, we suggest that the difference in phenology and voltinism between L. sinapis and L. reali is largely the result of environmentally implemented ecological pleiotropic effects caused by the between-species difference in habitat preference.
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| 20. |
- Gamberale-Stille, Gabriella, 1969-, et al.
(författare)
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Change in protective coloration in the striated shieldbug Graphosoma lineatum (Heteroptera: Pentatomidae) : predator avoidance and generalization among different life stages
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:2, s. 423-432
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Tidskriftsartikel (refereegranskat)abstract
- There are two major forms of protective coloration, camouflage and warning coloration, which often entail different colour pattern characteristics. Some species change strategy between or within life stages and one such example is the striated shieldbug, Graphosoma lineatum. The larvae and the pale brownish-and-black striated pre-diapause adults are more cryptic in the late summer environment than is the red-and black striation that the adults change to after diapause in spring. Here we investigate if the more cryptic pre-diapause adult and larval coloration may affect the aposematic function of the coloration as compared to the red adult form. In a series of trials we presented fifth instar larvae, pale or red adults to shieldbug-naïve domestic chicks, Gallus gallus domesticus, to investigate the birds’ initial wariness, avoidance learning, and generalization between the three prey types. The naïve chicks found the red adults most aversive followed by pale adults, and they found the larvae the least aversive. The birds did not find the larvae unpalatable and did not learn to avoid them, while they learned to avoid the two adult forms and then to a similar degree. Birds generalized asymmetrically between life stages, positively from larvae to adults and negatively from adults to larvae. We conclude that the lower conspicuousness in the pale forms of G. lineatum may entail a reduced aposematic function, namely a reduced initial wariness in inexperienced birds. The maintenance of the colour polymorphism is discussed
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| 21. |
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| 22. |
- Gómez-Llano, Miguel, et al.
(författare)
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Environmental variation shapes and links parasitism to sexual selection
- 2023
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Ingår i: Evolutionary Ecology. - : Springer. - 0269-7653 .- 1573-8477. ; 37:4, s. 585-600
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Tidskriftsartikel (refereegranskat)abstract
- Parasite-driven population divergence in hosts can be exacerbated by environmental factors affecting host parasitism, as well as by increasing sexual selection against parasitized hosts. Environmental factors can influence parasitism directly by affecting parasite survival, and indirectly by affecting host condition, which can in turn shape host sexual selection. To disentangle these potential alternative paths, we used a damselfly (host) - water mite (parasite) system to examine how environmental factors directly and indirectly drive heterogeneity in parasitism across populations and influence the strength of sexual selection acting against parasitized males. We found substantial heterogeneity in parasitism across populations, driven mainly by lake pH, and damselfly density. Although this heterogeneity in parasitism did not translate directly into variation in sexual selection, the density of predatory fish increased sexual selection strength, likely through the effects on damselfly condition. These results imply that parasitism alone may not cause differences in sexual selection across populations, but when linked with underlying environmental conditions, parasitism can increase the strength of selection. More broadly, these results suggest that elucidating how parasitism may drive sexual selection requires consideration of the intwined effects of ecological processes.
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| 23. |
- Göransson, Pernilla, et al.
(författare)
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Genetic adaptation to soil acidification: experimental evidence from four grass species
- 2009
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 23:6, s. 963-978
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic acidification has reduced soil pH and released potentially toxic aluminium (Al) ions in many regions. This investigation examines whether increased acidity has caused genetic adaptation to acidic conditions within the grass species Elymus caninus, Poa nemoralis, Deschampsia cespitosa and D. flexuosa. We sampled tussocks (genets) of each species in two regions of southern Sweden, differing in their exposure to acidifying deposition. The tolerance of the genets was tested in a solution experiment with different pH and Al concentrations. Our data suggest that species found at lower pH field locations have a greater tolerance to low pH and high Al levels than species found on less acidic soils. Analysis of variance showed a significant average effect of population and (or) genet in most species; however, we found little evidence of genetic adaptation to acidic conditions at the regional, population and micro-site level. In fact, there was no consistent change in the ranking of populations or genets with varying pH or Al concentration. Based on these results, we hypothesize that phenotypic plasticity rather than genetic adaptation has been favoured as the predominant mechanism to cope with soil acidity in the four grass species.
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| 24. |
- Haileselassie, Teklehaimanot, et al.
(författare)
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Effects of nutrient level on maternal choice and siring success in Cucumis sativus (Cucurbitaceae)
- 2005
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 19:3, s. 275-288
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Tidskriftsartikel (refereegranskat)abstract
- Plants have evolved many mechanisms to increase the chance of gene dispersal mainly through pollen and environmental factors play an important role. Understanding the mechanism behind gene dispersal is therefore crucial in the correct evaluation of the use of genetically modified crops for cultivation. In this paper we address the question of weather nutrient availability for the female affects the outcome of pollen competition between two pollen donor cultivars of Cucumis sativus. We do this by carrying out controlled crosses of female plants grown at three different nutrient levels. We separated the effect of a specific donor from the effect of pollen tube growth rate by using reversed crosses of fast and slow pollen. Our results show that female effects on siring ability vary with nutrient level. Pollen with a high pollen tube growth rate was more successful when nutrient availability for the female was high. This could be the result of selection on the female to adjust preference according to environmental circumstances. Pollen tube growth rate was measured under nutrient rich circumstances, thus high performers possessed traits adapted to a nutrient rich situation. Due to trade-off effects, these traits might not be advantageous in poor environments. Instead, individuals adapted to low nutrient circumstances will have a higher pollen tube growth rate. If siring ability varies with the environment of the recipient plant, this means that assessments of gene flow must account for this variation and include both pollen donors and recipient plants subjected to a range of environmental circumstances. In risk assessments of transgenic plants, plants are often kept under experimental, homogenous conditions. If our results also apply to other species, estimates of gene flow under constant conditions may be misleading. Selection on siring ability and female preference have fundamental effects on gene flow and need to be considered in risk assessments of transgenic plants.
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| 25. |
- Holmér, Jennie, et al.
(författare)
-
Adaptive branching in source-sink habitats
- 2010
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 24:2, s. 479-489
-
Tidskriftsartikel (refereegranskat)abstract
- Evolution and ecological diversification in a heterogeneous environment is driven by an often complex interplay between local adaptation and dispersal between different habitat types. Heterogeneous environments also easily generate source-sink dynamics of populations coupled by dispersal. It follows that local adaptation and possible adaptive radiation almost by necessity involves adaptation to a (pseudo-)sink habitat, which is considered unlikely. We here study a model of 'parapatric branching' with this special focus on the spatial ecology of the process. We find that evolutionary branching can display a sequence of alternating adaptations to the source or the sink. In some circumstances a true sink can become a pseudo-sink through adaptation to the corresponding source habitat. The evolutionary endpoint is a spatially structured community consisting of two source populations with one corresponding sink or pseudo-sink each. Our results shed new light on the interpretation of extant source-sink systems and the process of parapatric branching.
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| 26. |
- Huang, Chun Hua, et al.
(författare)
-
Investigating the role of body size, ecology, and behavior in anuran eye size evolution
- 2019
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 33:4, s. 585-598
-
Tidskriftsartikel (refereegranskat)abstract
- Vertebrate eye size typically scales hypoallemetrically with body size-as animals grow larger their eyes get relatively smaller. Additionally, eye size is highly variable across species, and such variability often reflects functional adaptations to differences in behavior and/or ecology. The selective pressures underlying the evolution of eye size are especially well studied in birds, mammals, and fishes. However, whether similar scaling rules and selective pressures also underlie the evolution of eye size in amphibians remains enigmatic. Variation in eye size is intimately linked with variation in brain anatomy, as the retina is ontogenetically part of the brain. Eye size may therefore coevolve with brain size. Here we use phylogenetic comparative methods to study interspecific variation in eye volume across 44 species of anurans from 8 families from the Hengduan Mountains, China. We relate this variation to key factors known to impact eye size evolution in other vertebrate taxa such as body mass, habitat use, defense strategy and foraging mobility. We found that also in anurans eyes size scaled hypoallometrically with body mass. However, neither of the behavioral or ecological factors explained any variation in relative eye size in our sample. Whether this is representative for other frog species needs to be clarified. We therefore conclude that eye size in frogs is tightly linked to body mass evolution but that, at least in the species investigated here, none of our tested ecological and behavioral factors have a strong influence on eye size evolution.
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| 27. |
- Härdling, Roger, et al.
(författare)
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Antagonistic coevolution under sexual conflict
- 2005
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 19:2, s. 137-150
-
Tidskriftsartikel (refereegranskat)abstract
- The theory of sexual conflict predicts that sexual coevolution will be very dynamic, with in principle perpetual evolutionary arms races and chases. These arms races are expected to stop once the costs of conflict adaptations become too high. We argue that this prediction is contingent on specific assumptions about the sexual interaction and the adaptations involved in the arms race. More generally, evolutionary arms races stop when the fitness benefit of further escalations is outweighed by the fitness costs. For this it is not necessary that the absolute costs of conflict must be high at the stable state, or that the population fitness must be decreased at equilibrium. We expect the outcome of sexual antagonistic coevolution to be determined by the possibility to reach compromises and by the relative ability of each sex to control the outcome of the interaction. We exemplify with a theoretical conflict model, which leads to population extinction when conflict is settled by armaments with expression-level determined costs. The model predicts a compromise with small conflict costs for the population, if costs are in addition determined by the extent of conflict between the sexes, which may be the case when the cost depends on behavioural antagonism.
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| 28. |
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| 29. |
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| 30. |
- Härlin, Carina, et al.
(författare)
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Towards a historization of aposematism
- 2003
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Ingår i: Evolutionary Ecology. - 0269-7653 .- 1573-8477. ; 17:2, s. 197-212
-
Tidskriftsartikel (refereegranskat)abstract
- Aposematism is one of the oldest phenomena in evolutionary biology and still a major puzzle to biologists. Despite its evolutionary nature, most attempts to understand aposematism are devoid of phylogenetic components. In addition, most studies that do take phylogeny into account need to bring the analysis even further. We argue that in order to fully understand aposematism we must have a clear picture of the evolutionary history behind present behaviours. In this paper we frame aposematism in a phylogenetic context and argue that most studies still are wanting in terms of demonstrating aposematism. Aposematism is not an end product but rather evolutionary scenarios including character transformations as well as prey-predator interactions. Finally, we suggest that, regardless how we restrict the concept of aposematism, knowing the directions of events facilitate all kinds of comparisons with a promise of uniting functional and evolutionary aspects into a historization of aposematism.
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| 31. |
- Jack, C. N., et al.
(författare)
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Third-party mutualists have contrasting effects on host invasion under the enemy-release and biotic-resistance hypotheses
- 2017
-
Ingår i: Evolutionary Ecology. - : Springer International Publishing. - 0269-7653 .- 1573-8477. ; 31:6, s. 829-845
-
Tidskriftsartikel (refereegranskat)abstract
- Plants engage in complex multipartite interactions with mutualists and antagonists, but these interactions are rarely included in studies that explore plant invasiveness. When considered in isolation, we know that beneficial microbes can enhance an exotic plant’s invasive ability and that herbivorous insects often decrease an exotic plant’s likeliness of success. However, the effect of these partners on plant fitness has not been well characterized when all three species coevolve. We use computational evolutionary modeling of a trait-based system to test how microbes and herbivores simultaneously coevolving with an invading plant affect the invaders’ probability of becoming established. Specifically, we designed a model that explores how a beneficial microbe would influence the outcome of an interaction between a plant and herbivore. To model novel interactions, we included a phenotypic trait shared by each species. Making this trait continuous and selectable allows us to explore how trait similarities between coevolving plants, herbivores and microbes affect fitness. Using this model, we answer the following questions: (1) Can a beneficial plant-microbe interaction influence the evolutionary outcome of antagonistic interactions between plants and herbivores? (2) How does the initial trait similarity between interacting organisms affect the likelihood of plant survival in novel locations? (3) Does the effect of tripartite interactions on the invasion success of a plant depend on whether organisms interact through trait similarity [Enemy Release Hypothesis (ERH)] or dissimilarity (Biotic Resistance Hypothesis)? We found that it was much more difficult for plants to invade under the ERH but that beneficial microbes increase the probability of plant survival in a novel range under both hypotheses. To our knowledge, this model is the first to use tripartite interactions to explore novel species introductions. It represents a step towards gaining a better understanding of the factors influencing establishment of exotic species to prevent future invasions. © 2017, The Author(s).
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| 32. |
- Jakalaniemi, A., et al.
(författare)
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Variability of important vital rates challenges the demographic buffering hypothesis
- 2013
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 27:3, s. 533-545
-
Tidskriftsartikel (refereegranskat)abstract
- Selection is assumed to eliminate life-histories showing high variability in vital rates that have the greatest influence on population performance. Therefore, an inverse variability-importance relationship of vital rates is believed to be a universal pattern for diverse life-histories. We tested for such a relationship using multi-year demographic data on a large number of populations of two perennial plant species. Applying different approaches, we first examined the overall variability-importance relationship for the average main vital rates (survival, growth, retrogression, fecundity) per species, and then separately for each population. We found an overall inverse relationship between temporal variation and importance of the average main vital rates for both study species, but these negative species-level correlations were mainly caused by different scales of the examined vital rates. When variability-importance relationships were examined across individual demographic transitions within populations, the abundance of positive and negative correlations depended largely on the method used, and positive correlations were more common after correcting vital rates for sampling variation than when using uncorrected vital rates. Our results cast doubt on the generality of the demographic buffering hypothesis, suggesting that the inverse variability-importance relationship may not be a universal pattern when vital rates are examined for multiple populations of the same plant species.
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| 33. |
- Jakobsson, A, et al.
(författare)
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Local adaptation and the effects of isolation and population size - the semelparous perennial Carlina vulgaris as a study case
- 2005
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 19:5, s. 449-466
-
Tidskriftsartikel (refereegranskat)abstract
- We made a reciprocal transplantation experiment with Carlina vulgaris, among 12 semi-natural grassland sites situated in southwest Sweden. The fate of seeds and seedlings were followed during 2 years. Local adaptation was investigated both by native superiority over non-natives, and by comparing the observed performance of a population to the fitted value of a reduced statistical model that showed the populations' performance at all sites and the performance of all other populations at its home site. The latter method indicates presence of local adaptation even when natives are inferior to introduced populations as long as the negative difference in fitness between the populations is smaller at the native population's home site. The strength of local adaptation was measured as the ratio of the observed to the expected performance in reduced statistical models and regressed on the degree of isolation and population size. We found no evidence of local adaptation in terms of native superiority compared to non-natives, but with the relative method we found one of six fitness components, juvenile survival, to be 6% higher for natives at their home sites compared to how they performed at other sites and how others performed at their site. Further, our results indicate that both isolation and population size have a positive effect on the process of local adaptation.
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| 34. |
- Janz, Niklas, et al.
(författare)
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Frequency dependence of host plant choice within and between patches : a large cage experiment
- 2005
-
Ingår i: Evolutionary Ecology. - : Springer. - 0269-7653 .- 1573-8477. ; 19:3, s. 289-302
-
Tidskriftsartikel (refereegranskat)abstract
- Oviposition preference is considered to be one of the most important factors behind patterns of host use among herbivorous insects. However, preference is defined as host plant choice under equal host abundance and availability, and it is likely that frequency-dependent effects will alter the actual pattern of host use beyond what preference trials reveals. The effects of such alterations are poorly known but could be important for the understanding of specialization and host shifts. We investigated how changes in frequency of a preferred and a less preferred host affected movement patterns and egg deposition within and among patches in a polyphagous butterfly, Polygonia c-album. Two experiments were carried out in large (8 × 30 m) outdoor cages, artificially divided into distinct patches with different frequencies of the two hosts: one that allowed for limited movement between patches and one that did not. There was a clear effect of frequency on patch selection; females spent more time in and laid more eggs in patches with a high frequency of the preferred host, which will potentially have a large effect on host use by modifying encounter rates in favor of the preferred host. However, there was no significant frequency-dependent plant choice within patches in any experiment. Instead, results indicate that females are distributing their eggs among plants species according to specific likelihoods of oviposition, independent of encounter rates, which is compatible with a strategy of risk-spreading.
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| 35. |
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| 36. |
- Johansson, Frank, et al.
(författare)
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Evolution of the G-matrix in life history traits in the common frog during a recent colonisation of an island system
- 2012
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 26:4, s. 863-878
-
Tidskriftsartikel (refereegranskat)abstract
- Studies of genetic correlations between traits that ostensibly channel the path of evolution away from the direction of natural selection require information on key aspects such as ancestral phenotypes, the duration of adaptive evolution, the direction of natural selection, and genetic covariances. In this study we provide such information in a frog population system. We studied adaptation in life history traits to pool drying in frog populations on islands of known age, which have been colonized from a mainland population. The island populations show strong local adaptation in development time and size. We found that the first eigenvector of the variance-covariance matrix (g (max)) had changed between ancestral mainland populations and newly established island populations. Interestingly, there was no divergence in g (max) among island populations that differed in their local adaptation in development time and size. Thus, a major change in the genetic covariance of life-history traits occurred in the colonization of the island system, but subsequent local adaptation in development time took place despite the constraints imposed by the genetic covariance structure.
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| 37. |
- Johansson, Frank, et al.
(författare)
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Predation and the relative importance of larval colour polymorphisms and colour polyphenism in a damselfly
- 2013
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 27:3, s. 579-591
-
Tidskriftsartikel (refereegranskat)abstract
- Intraspecific body colour variation is common in many animal species. Predation could be a key selective agent giving rise to variation in body colour, and such variation could be due to genetics (polymorphisms) or phenotypic plasticity (polyphenisms). In this study we examined the degree of colour polymorphism and polyphenism in background colour matching in larvae of the damselfly Coenagrion armatum. In addition, we tested if predation risk is reduced when larvae are exposed to a matching compared to a non-matching background. By raising families of larvae at three different background colours we showed that polymorphism explained about 20 % of the total variation and polyphenism about 35 %. In a predation experiment with fish, we showed that larvae with a body colour matching the background had a higher survival success compared to larvae with a non-matching background colour. We suggest that the background matching is adaptive in terms of survival from predation and that colour diversity is maintained because of spatial and temporal variation in the background experienced by damselfly larvae under field conditions.
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| 38. |
- Jörgensen, Tove, et al.
(författare)
-
The potential for selection on pollen colour dimorphisms in Nigella degenii: morph-specific differences in pollinator visitation, fertilisation success and siring ability
- 2006
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; 20:4, s. 291-306
-
Tidskriftsartikel (refereegranskat)abstract
- Two subspecies of Nigella degenii (Ranunculaceae) possess a dimorphism in pollen colour and vary extensively in frequency of the two morphs in natural populations. Here we investigate the role of selection on pollen colour during the pollination phase in the two subspecies and its potential contribution to the maintenance of this colour variation. In a combination of common garden experiments and field observations, we obtained data on pollinator visitation rates and explored the effect of pollen colour on fertilisation success and siring ability under conditions of low vs. high pollen competition. In experimental gardens, naive pollinators responded differently to plants with different pollen colour, but the favoured morph varied between dates and locations, and colour morphs were not visited in a frequency-dependent manner. Donor plants with dark pollen had a reproductive advantage (higher seed set) in single-donor pollinations, but the realised siring ability (measured by progeny morph ratio) was highly variable between different two-donor crosses with no general bias towards the light or dark morph. Therefore, although the dark pollen type appears to have a general selective advantage in terms of fertilisation success, our data are also consistent with a scenario involving the maintenance of both colour morphs, particularly under conditions of high pollen competition, a variable genetic background and/or spatial or temporal variation in the pollinator fauna.
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| 39. |
- Karlsson, Magnus, et al.
(författare)
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Is melanism in pygmy grasshoppers induced by crowding?
- 2010
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:5, s. 975-983
-
Tidskriftsartikel (refereegranskat)abstract
- Color polymorphisms in animals may result from plasticity of the developmental system in response to genetic cues in the form of allelic variation at polymorphic loci, environmental cues, or a combination of genetic and environmental cues. An increased understanding of the evolution of color polymorphisms requires better knowledge of when we should expect genetic and environmental cues respectively to influence phenotype determination. Theory posits that the developmental systems of organisms should evolve sensitivity to such cues that most accurately predict coming selective conditions. Pygmy grasshoppers (Orthoptera, Tetrigidae) vary in color pattern within and among populations and show fire melanism, i.e., an increased frequency of black and dark colored phenotypes in high density populations inhabiting fire-ravaged areas. We examined if the population density experienced by individuals during development influenced the phenotypic expression of color pattern in Tetrix subulata. Individuals were experimentally reared either in solitude, at intermediate density or under crowded conditions. We found that color patterns of experimental individuals were independent of rearing density but strongly influenced by maternal color pattern. High population density and crowding may not constitute reliable predictors of the selective regime that characterizes post-fire environments.
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| 40. |
- Karpestam, Einat, et al.
(författare)
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Matching habitat choice by experimentally mismatched phenotypes
- 2012
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 26:4, s. 893-907
-
Tidskriftsartikel (refereegranskat)abstract
- Gene flow is often regarded a random process that homogenizes differencesbetween populations and constrains local adaptation. However, the matching habitat choicehypothesis posits that individuals actively choose those microhabitats that best match theirspecific phenotype to maximize fitness. Dispersal (and possibly gene flow) may thus bedirected. Many studies report associations between habitats and phenotypes, but they mayreflect selection, plasticity or adaptation rather than matching choice. Here, we test twopredictions from the matching habitat choice hypothesis by manipulating the dorsal colourof Tetrix subulata, a pygmy grasshopper. (1) Is microhabitat choice flexible such thatdifferently manipulated phenotypes distribute themselves differently in a microclimaticand solar radiation mosaic? (2) If they do, are their fitness prospects higher in the morepreferred microhabitat? We find that individuals painted white or black do distributethemselves differently, with black individuals residing in habitats with less radiation, onaverage, than white individuals, demonstrating that microhabitat choices are plastic. Furthermore,white females had more hatchlings than black ones in the increased radiationtreatment, and this was mainly due to increased mortality of black females under increasedradiation. These findings provide rare experimental evidence in line with predictions fromthe matching habitat choice hypothesis.
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| 41. |
- Kolb, Annette, et al.
(författare)
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Environmental context drives seed predator-mediated selection on a floral display trait
- 2010
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:2, s. 433-445
-
Tidskriftsartikel (refereegranskat)abstract
- Linking trait selection to environmental context is necessary to move beyond the simple recognition that selection is spatially variable and to understand what ultimately drives this variation. Natural selection acts through differences among individuals in lifetime fitness and information about effects on fitness components is therefore often not sufficient to gain such an understanding. We investigated how environmental context influenced intensity of seed predation, flower abortion and selection on floral display traits in 44-52 populations of the perennial herb Primula veris over 2 years. Phenotypic selection on both inflorescence height and flower number varied among populations and was mediated partly by pre-dispersal seed predation and flower abortion in one of the years. Among-population variation in selection on inflorescence height, but not flower number, was linked to variation in canopy cover via its effects on seed predation. Lifetime fitness was less sensitive to seed predator damage in shaded environments but estimates of selection based on lifetime fitness agreed qualitatively with those based on seed output. Our results demonstrate that seed predators constitute an important link between environmental conditions and trait evolution in plants, and that selection on plant traits by seed predators can depend on environmental context.
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| 42. |
- Kotrschal, Alexander, et al.
(författare)
-
Life-stage specific environments in a cichlid fish : implications for inducible maternal effects
- 2012
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 26:1, s. 123-137
-
Tidskriftsartikel (refereegranskat)abstract
- Through environmentally induced maternal effects females may fine-tune their offspring's phenotype to the conditions offspring will encounter after birth. If juvenile and adult ecologies differ, the conditions mothers experienced as juveniles may better predict their offspring's environment than the adult females' conditions. Maternal effects induced by the environment experienced by females during their early ontogeny should evolve when three ecological conditions are met: (1) Adult ecology does not predict the postnatal environmental conditions of offspring; (2) Environmental conditions for juveniles are correlated across successive generations; and (3) Juveniles occasionally settle in conditions that differ from the juvenile habitat of their mothers. By combining size-structured population counts, ecological surveys and a genetic analysis of population structure we provide evidence that all three conditions hold for Simochromis pleurospilus, a cichlid fish in which mothers adjust offspring quality to their own juvenile ecology. In particular we show (1) that the spatial niches and the habitat quality differ between juveniles and adults, and we provide genetic evidence (2) that usually fish of successive generations grow up in similar habitats, and (3) that occasional dispersal in populations with a different habitat quality is likely to occur. As adults of many species cannot predict their offspring's environment from ambient cues, life-stage specific maternal effects are likely to be common in animals. It will therefore be necessary to incorporate parental ontogeny in the study of parental effects when juveniles and adults inhabit different environments.
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| 43. |
- Kotrschal, Alexander, et al.
(författare)
-
Predation pressure shapes brain anatomy in the wild
- 2017
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 31:5, s. 619-633
-
Tidskriftsartikel (refereegranskat)abstract
- There is remarkable diversity in brain anatomy among vertebrates and evidence is accumulating that predatory interactions are crucially important for this diversity. To test this hypothesis, we collected female guppies (Poecilia reticulata) from 16 wild populations and related their brain anatomy to several aspects of predation pressure in this ecosystem, such as the biomass of the four major predators of guppies (one prawn and three fish species), and predator diversity (number of predatory fish species in each site). We found that populations from localities with higher prawn biomass had relatively larger telencephalon size as well as larger brains. Optic tectum size was positively associated with one of the fish predator's biomass and with overall predator diversity. However, both olfactory bulb and hypothalamus size were negatively associated with the biomass of another of the fish predators. Hence, while fish predator occurrence is associated with variation in brain anatomy, prawn occurrence is associated with variation in brain size. Our results suggest that cognitive challenges posed by local differences in predator communities may lead to changes in prey brain anatomy in the wild.
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| 44. |
- Kotrschal, Alexander, et al.
(författare)
-
The mating brain : early maturing sneaker males maintain investment into the brain also under fast body growth in Atlantic salmon (Salmo salar)
- 2014
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 28:6, s. 1043-1055
-
Tidskriftsartikel (refereegranskat)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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| 45. |
- Kristensen, Nadiah Pardede, et al.
(författare)
-
Evolution of resident bird breeding phenology in a landscape with heterogeneous resource phenology and carryover effects
- 2018
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 32:5, s. 509-528
-
Tidskriftsartikel (refereegranskat)abstract
- It is generally expected that, in environments with pronounced seasonal resource peaks, birds’ reproductive success will be maximised when nestlings’ peak food demand coincides with the timing of high food availability. However in certain birds that stay resident over winter, earlier breeding leads juveniles to join the winter flock earlier, which by the prior residence effect increases their success in breeding territory competition. This trade-off between reproduction and competition may explain why, in certain species, breeding phenology is earlier and asynchronous with the resource. This study extends a previous model of the evolution of breeding phenology in a single habitat type to a landscape with two habitat types: ‘early’ and ‘late’ resource phenology. The offspring’s natal habitat type has a carryover effect upon their competitive ability regardless of which habitat type they settle in to potentially breed. We find that, when the difference in resource phenology between habitats is small (weak carryover effect), breeding phenology in the late habitat evolves to occur earlier and more asynchronously than in the early habitat, to compensate for the competitive disadvantage to juveniles raised there. However if the difference is large (strong carryover effect), then the reproductive cost of earlier breeding outweighs the benefit of the compensation, so instead breeding phenology in the late habitat evolves to become more synchronous with the resource. Recruitment is generally asymmetric, from early to late habitat type. However if the early habitat is less frequent in the landscape or produces fewer offspring, then the asymmetry is reduced, and if there is some natal habitat-type fidelity, then recruitment can have an insular pattern, i.e. most recruits to each habitat type come from that same habitat type. We detail the different scenarios in which the different recruitment patterns are predicted, and we propose that they have implications for local adaptation.
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| 46. |
- Lankinen, Åsa, et al.
(författare)
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Conflicting selection pressures on reproductive functions and speciation in plants.
- 2009
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 23:1, s. 147-157
-
Konferensbidrag (refereegranskat)abstract
- Recent developments in the field of genetic divergence and speciation focus more on diversifying processes than on geographic mode of speciation (i.e. allopatric versus sympatric). Some of these new theories concern speciation driven by conflicts between the sexes. Even though it is well known that the two reproductive functions in plants can have different selective optima, sexual selection in plants is by many assumed to be weak or non-existent. Here we outline potential sexual conflicts in plants and discuss how selection pressures generated by such conflicts may influence genetic divergence. There is opportunity for conflicting selection pressures between individuals, such as manipulative pollen traits that enhance male reproductive success at the expense of the female reproductive function. Within individual plants, fitness of the male function (pollen export) and fitness of the female function (pollen import) may be optimised by different traits, leading to conflicting selection pressures in relation to pollen transfer. This may affect selection for floral specialisation versus floral generalisation in animal-pollinated species. We believe that selection pressures generated by sexual conflict need to be appreciated in order to fully understand microevolutionary processes which may lead to genetic divergence and speciation in plants.
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| 47. |
- Lankinen, Åsa, et al.
(författare)
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Effect of root contact on pollen competitive ability in a hermaphroditic winter-annual herb
- 2016
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 30:4, s. 739-754
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Tidskriftsartikel (refereegranskat)abstract
- Presence of a root neighbor can induce changes in root allocation and pollen traits, but only a limited number of studies have investigated such effects on pollen. To learn more about effects of root contact on pollen competitive ability, we studied plants of the hermaphroditic winter-annual Collinsia heterophylla, native to California. We cultivated plants in two-pot treatments with roots kept either separate or intermingled with the same amount of resources. Pollen-tube growth rate, as an indication of pollen competitive ability, was affected by root treatment but the response varied among competing plant families. The response to root-treatment was not an effect of differential resource uptake of the two competitors. Root biomass was significantly higher when roots were intermingled compared to separate. This finding adds to the number of species with a strategic root response in the presence of competitors, but could also be a consequence of a larger rooting volume. Allocation to pollen performance versus roots in the presence of a competitor was lower in small plants and higher in large plants, potentially implying high costs of producing competitive pollen. We conclude that our study demonstrated that pollen tube growth rate is highly sensitive to the root environment in C. heterophylla.
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| 48. |
- Lehmann, Philipp, et al.
(författare)
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Latitudinal differences in diapause related photoperiodic responses of European Colorado potato beetles (Leptinotarsa decemlineata)
- 2015
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 29:2, s. 269-282
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Tidskriftsartikel (refereegranskat)abstract
- Many organisms use photoperiodic cues to assess seasonal progression and pace their phenology. As photoperiod correlates with latitude, range expansions in seasonal environments may require re-synchronization of phenology and life-history traits with novel season length. Adaptive resynchronization takes time, and hence might be one factor explaining why range expansion to higher latitudes often is slow. Studies investigating latitudinal clines in photoperiodic traits often focus on species or populations which are well established. However, studying organisms which are in the process of expanding their range can provide valuable information on the evolutionary ecological mechanisms driving the adaptive synchronization to seasonal environments. The Colorado potato beetle, Leptinotarsa decemlineata, is a pest of potato, which rapidly has spread towards higher latitudes. We studied whether beetles from six European populations along a latitudinal axis are synchronized with their local photoperiodic environmental conditions. Variation in critical photoperiod (when 50 % of individuals make the decision to overwinter), diapause incidence, burrowing age for diapause and resurfacing behaviour were investigated by maintaining beetles under six photoperiods. The beetles showed a clear latitudinal pattern in diapause incidence and burrowing age for diapause but not in critical photoperiod. Resurfacing behaviour of burrowed beetles increased with the length of the photoperiod, which through unsynchronized overwintering behaviour could lead to high overwintering mortality. Thus, while synchronization of diapause preparation with local photoperiodic conditions can be one reason explaining the success of L. decemlineata in expanding to higher latitudes, further northward range expansion could be constrained by inherent difficulties to initiate overwintering under very long photoperiods.
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| 49. |
- Leimar, Olof, 1949-
(författare)
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Environmental and genetic cues in the evolution of phenotypic polymorphism
- 2009
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 23, s. 125-135
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic polymorphism is a consequence of developmental plasticity, in which the trajectories of developing organisms diverge under the influence of cues. Environmental and genetic phenotype determination are the two main categories of polymorphic development. Even though both may evolve as a response to varied environments, they are traditionally regarded as fundamentally distinct phenomena. They can however be joined into a single framework that emphasizes the parallel roles of environmental and genetic cues in phenotype determination. First, from the point of view of immediate causation, it is common that phenotypic variants can be induced either by environmental or by allelic variation, and this is referred to as gene-environment interchangeability. Second, from the point of view of adaptation, genetic cues in the form of allelic variation at polymorphic loci can play similar roles as environmental cues in providing information to the developmental system about coming selective conditions. Both types of cues can help a developing organism to fit its phenotype to selective circumstances. This perspective of information in environmental and genetic cues can produce testable hypotheses about phenotype determination, and can thus increase our understanding of the evolution of phenotypic polymorphism.
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| 50. |
- Lindgren, Beatrice, et al.
(författare)
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Are high-latitude individuals superior competitors? : A test with Rana temporaria tadpoles
- 2010
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 24:1, s. 115-131
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Tidskriftsartikel (refereegranskat)abstract
- Species with a wide distribution over latitudinal gradients often exhibit increasing growth and development rates towards higher latitudes. Ecological theory predicts that these fast-growing genotypes are, in the absence of trade-offs with fast growth, better competitors than low-latitude conspecifics. While knowledge on key ecological traits along latitudinal clines is important for understanding how these clines are maintained, the relative competitive ability of high latitude individuals against low latitude conspecifics has not been tested. Growth and development rates of the common frog Rana temporaria increase along the latitudinal gradient across Scandinavia. Here we investigated larval competition over food resources within and between two R. temporaria populations originating from southern and northern Sweden in an outdoor common garden experiment. We used a factorial design, where southern and northern tadpoles were reared either as single populations or as mixes of the two populations at two densities and predator treatments (absence and non-lethal presence of Aeshna dragonfly larvae). Tadpoles from the high latitude population grew and developed faster and in the beginning of the experiment they hid less and were more active than tadpoles from the low latitude population. When raised together with high latitude tadpoles the southern tadpoles had a longer larval period, however, the response of high latitude tadpoles to the competition by low latitude tadpoles did not differ from their response to intra-population competition. This result was not significantly affected by density or predator treatments. Our results support the hypothesis that high latitude populations are better competitors than their low latitude conspecifics, and suggest that in R. temporaria fast growth and development trade off with other fitness components along the latitudinal gradient across Scandinavia.
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