| 1. |
- Björnerås, Caroline, et al.
(författare)
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Inland blue holes of The Bahamas - chemistry and biology in a unique aquatic environment
- 2020
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Ingår i: Fundamental and Applied Limnology. - : Schweizerbart science publishers. - 1863-9135. ; 194:2, s. 95-106
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Tidskriftsartikel (refereegranskat)abstract
- While lake systems in temperate regions have been extensively studied, tropical and subtropical systems have received less attention. Here, we describe the water chemistry and biota of ten inland blue holes on Andros Island, The Bahamas, representative of the morphological, abiotic, and biotic variation among Androsian inland blue holes. The majority of the studied blue holes were vertically stratified with oxic freshwater overlying anoxic saline groundwater of marine origin. Water chemistry (e.g. total phosphorus and nitrogen) in shallow waters was similar among blue holes, while turbidity and water color varied. Presence of hydrogen sulfide and reduced iron in and below the halocline indicate reducing conditions in all stratified blue holes. The biota above the halocline was also similar among blue holes with a few taxa dominating the phytoplankton community, and the zooplankton community consisting of copepods and rotifers. The Bahamas mosquitofish (Gambusia hubbsi) was present in all investigated blue holes, often accompanied by other small planktivorous fish, while the piscivorous bigmouth sleeper (Gobiomorus donnitor) was only present in some of the blue holes. Our field study reinforces that inland blue holes are highly interesting for biogeochemical research, and provide naturally replicated systems for evolutionary studies.
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| 2. |
- Chapman, Ben, et al.
(författare)
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Sex and the Syndrome: Individual and Population Consistency in Behaviour in Rock Pool Prawn Palaemon elegans
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- Animal personality has been widely documented across a range of species. The concept of personality is composed of individual behavioural consistency across time and between situations, and also behavioural trait correlations known as behavioural syndromes. Whilst many studies have now investigated the stability of individual personality traits, few have analysed the stability over time of entire behavioural syndromes. Here we present data from a behavioural study of rock pool prawns. We show that prawns are temporally consistent in a range of behaviours, including activity, exploration and boldness, and also that a behavioural syndrome is evident in this population. We find correlations between many behavioural traits (activity, boldness, shoaling and exploration). In addition, behavioural syndrome structure was consistent over time. Finally, few studies have explicitly studied the role of sex differences in personality traits, behavioural consistency and syndrome structure. We report behavioural differences between male and female prawns but no differences in patterns of consistency. Our study adds to the growing literature on animal personality, and provides evidence showing that syndromes themselves can exhibit temporal consistency.
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| 3. |
- Hegg, Alexander, et al.
(författare)
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A field experiment reveals seasonal variation in the Daphnia gut microbiome
- 2021
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 130:12, s. 2191-2201
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Tidskriftsartikel (refereegranskat)abstract
- The gut microbiome is increasingly recognized for its impact on host fitness, but it remains poorly understood how naturally variable environments influence gut microbiome diversity and composition. We studied changes in the gut microbiome of ten genotypes of water fleas Daphnia magna in submerged mesocosm enclosures in a eutrophic lake over a period of 16 weeks, from early summer to autumn. The microbial diversity increased when Daphnia were reintroduced from the laboratory to the lake, and the composition of gut microbes drastically changed. Both gut microbiome diversity and composition continued to change over the 16-week period, with alpha diversity peaking in late summer. The gut microbiome community was clearly distinct from that of the surrounding water, and temporal changes in the two communities were independent of each other. There were no consistent differences in the gut microbiomes among Daphnia genotypes in the lake environment. The change in gut microbiome over the season was accompanied by a decline in reproductive output and survival. There were weak, but statistically supported, effects of microbiota composition on Daphnia fitness, but there was no evidence that natural variation in microbiome diversity or composition was associated with tolerance to the cyanotoxin microcystin. We conclude that the gut microbiome of Daphnia is highly dynamic in a natural lake environment, but that host genetic effects on microbiome diversity and composition between genotypes within a population can be vanishingly small. These results emphasize that establishing the ecological effects of gut microbiota will require large-scale experiments under natural conditions.
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| 4. |
- Hegg, Alexander
(författare)
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Adaptive and non-adaptive responses to toxin-producing cyanobacteria in water fleas
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organisms regularly encounter stressful conditions that negatively affects their fitness. One way to minimize these negative effects is to use cues from the environment in order to develop an appropriate phenotype. Many populations of water fleas (Daphnia spp.) are exposed to algal blooms dominated by toxin- producing cyanobacteria during parts of the summer season, which can reduce growth, reproductive output and survival. Theory suggests that seasonal exposure to toxic cyanobacteria will favour maternal and transgenerational effects that promote tolerance. However, it is poorly understood if, and to what extent, Daphnia can develop tolerance when exposed to toxins over one or several generations.Here, I first investigate the scope and efficacy of maternal (Paper I) and transgenerational (Paper II) effects in this system. Secondly, I examined how the overall fitness, and tolerance to the cyanotoxin microcystin in particular, changes across the season in a natural lake environment (Paper III and IV). Finally, I attempted to link variation in growth, reproductive output and survival to changes in the diversity and composition of the gut microbiome (Paper II and IV), one possible mechanism that enable cumulative transgenerational adaptive change in response to a toxic diet.In agreement with previous studies, I find that exposure to toxin-producing cyanobacteria consistently reduces fitness in Daphnia, both in terms of reproductive output and survival. The ability of mothers to transfer tolerance to their offspring was limited (Paper I), and there was little evidence that these positive effects accumulate across several generations (Paper II). These results fit well with studies of natural seasonal variation in how microcystin-producing cyanobacteria affected fitness, which provided no robust evidence for an increase in tolerance following blooms (Paper III and IV). Instead, the fitness of Daphnia declined steadily over the season in both experiments, an effect that could partly be attributed to natural exposure to microcystin-producing cyanobacteria (Paper III).The gut microbiome was strongly influenced by seasonal changes in a lake environment (Paper IV). The microbiome was also affected by different cyanobacteria environments in the laboratory (Paper II), but these effects were only weakly correlated with the ability to tolerate microcystin-producing cyanobacteria.In summary, this work shows that there are both adaptive and non-adaptive responses to toxin-producing cyanobacteria in Daphnia. The adaptive value of transgenerational effects in this system was consistently small, and does not support the existence of a dedicated machinery to transfer information between generations. This probably also means that induced changes in tolerance within a season have a limited influence on the dynamics of Daphnia populations, even in populations that are recurrently exposed to toxic algal blooms.
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| 5. |
- Hegg, Alexander, et al.
(författare)
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Seasonal variation in the response to a toxin-producing cyanobacteria in Daphnia
- 2022
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 67:6, s. 1035-1044
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Tidskriftsartikel (refereegranskat)abstract
- Many populations of water fleas (Daphnia) are exposed to algal blooms dominated by microcystin-producing cyanobacteria. However, the severity of these effects on Daphnia fitness remain poorly understood in natural populations. We investigated seasonal changes in body size, reproduction and survival of D. longispina individuals from five eutrophic lakes in southern Sweden. We tested whether individuals collected before, during or following algal blooms differed in their reproduction and survival when experimentally exposed to microcystin-producing cyanobacteria. The concentration of microcystin in the lakes was significantly higher during summer and autumn compared to spring, but there were substantial differences between lakes. The reproductive output of individuals declined consistently over the season, and this decline was stronger for Daphnia collected during periods of, or from lakes with, high microcystin concentration. There was little evidence that individuals adapted to the toxin over the season. The strong seasonal changes in body size, reproduction and survival in these D. longispina appear to be caused partly by variation in the abundance of toxin-producing cyanobacteria. Populations were unable to adapt sufficiently quickly during summer and autumn to recover from the negative effects of microcystin. We therefore suggest that seasonal increases in tolerance to microcystin-producing cyanobacteria have limited effects on the eco-evolutionary dynamics between Daphnia and phytoplankton.
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| 6. |
- Lee, Marcus, et al.
(författare)
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Low-latitude zooplankton pigmentation plasticity in response to multiple threats
- 2019
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Ingår i: Royal Society Open Science. - : Royal Society Open Science. - 2054-5703. ; 6:7, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation ( UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian 'blue hole' copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.
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| 7. |
- Radersma, Reinder, et al.
(författare)
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Timing of maternal exposure to toxic cyanobacteria and offspring fitness in Daphnia magna : Implications for the evolution of anticipatory maternal effects
- 2018
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 8:24, s. 12727-12736
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Tidskriftsartikel (refereegranskat)abstract
- Organisms that regularly encounter stressful environments are expected to use cues to develop an appropriate phenotype. Water fleas (Daphnia spp.) are exposed to toxic cyanobacteria during seasonal algal blooms, which reduce growth and reproductive investment. Because generation time is typically shorter than the exposure to cyanobacteria, maternal effects provide information about the local conditions subsequent generations will experience. Here, we evaluate if maternal effects in response to microcystin, a toxin produced by cyanobacteria, represent an inheritance system evolved to transmit information in Daphnia magna. We exposed mothers as juveniles and/or as adults, and tested the offspring's fitness in toxic and non-toxic environments. Maternal exposure until reproduction reduced offspring fitness, both in the presence and in the absence of toxic cyanobacteria. However, this effect was accompanied by a small positive fitness effect, relative to offspring from unexposed mothers, in the presence of toxic cyanobacteria. This effect was mainly elicited in response to maternal exposure to toxic cyanobacteria early in life and less so during reproduction. None of these effects were explained by changes in egg size. A meta-analysis using our and others’ experiments suggests that the adaptive value of maternal effects to cyanobacteria exposure is weak at best. We suggest that the beneficial maternal effect in our study is an example of phenotypic accommodation spanning generations, rather than a mechanism evolved to transmit information about cyanobacteria presence between generations.
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| 8. |
- Vinterstare, Jerker, et al.
(författare)
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Predation risk and the evolution of a vertebrate stress response : Parallel evolution of stress reactivity and sexual dimorphism
- 2021
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Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons. - 1010-061X .- 1420-9101. ; 34:10, s. 1554-1567
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Tidskriftsartikel (refereegranskat)abstract
- Predation risk is often invoked to explain variation in stress responses. Yet, the answers to several key questions remain elusive, including the following: (1) how predation risk influences the evolution of stress phenotypes, (2) the relative importance of environmental versus genetic factors in stress reactivity and (3) sexual dimorphism in stress physiology. To address these questions, we explored variation in stress reactivity (ventilation frequency) in a post-Pleistocene radiation of live-bearing fish, where Bahamas mosquitofish (Gambusia hubbsi) inhabit isolated blue holes that differ in predation risk. Individuals of populations coexisting with predators exhibited similar, relatively low stress reactivity as compared to low-predation populations. We suggest that this dampened stress reactivity has evolved to reduce energy expenditure in environments with frequent and intense stressors, such as piscivorous fish. Importantly, the magnitude of stress responses exhibited by fish from high-predation sites in the wild changed very little after two generations of laboratory rearing in the absence of predators. By comparison, low-predation populations exhibited greater among-population variation and larger changes subsequent to laboratory rearing. These low-predation populations appear to have evolved more dampened stress responses in blue holes with lower food availability. Moreover, females showed a lower ventilation frequency, and this sexual dimorphism was stronger in high-predation populations. This may reflect a greater premium placed on energy efficiency in live-bearing females, especially under high-predation risk where females show higher fecundities. Altogether, by demonstrating parallel adaptive divergence in stress reactivity, we highlight how energetic trade-offs may mould the evolution of the vertebrate stress response under varying predation risk and resource availability.
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