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  • 1. Araújo, M.S.
    et al.
    Guimarães, P.R.
    Svanbäck, R.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pinheiro, A.
    Guimarães, P.
    Dos Reis, S.F.
    Bolnick, D.I.
    Network analysis reveals contrasting effects of intraspecific competition on individual versus population diets2008In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 89, no 7, p. 1981-1993Article in journal (Refereed)
    Abstract [en]

    Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanback and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.

  • 2.
    Bartels, Pia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hirsch, Philipp E
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 8, p. e43641-Article in journal (Refereed)
    Abstract [en]

    Trait combinations that lead to a higher efficiency in resource utilization are important drivers of divergent natural selection and adaptive radiation. However, variation in environmental features might constrain foraging in complex ways and therefore impede the exploitation of critical resources. We tested the effect of water transparency on intra-population divergence in morphology of Eurasian perch (Perca fluviatilis) across seven lakes in central Sweden. Morphological divergence between near-shore littoral and open-water pelagic perch substantially increased with increasing water transparency. Reliance on littoral resources increased strongly with increasing water transparency in littoral populations, whereas littoral reliance was not affected by water transparency in pelagic populations. Despite the similar reliance on pelagic resources in pelagic populations along the water transparency gradient, the utilization of particular pelagic prey items differed with variation in water transparency in pelagic populations. Pelagic perch utilized cladocerans in lakes with high water transparency and copepods in lakes with low water transparency. We suggest that under impaired visual conditions low utilization of littoral resources by littoral perch and utilization of evasive copepods by pelagic perch may lead to changes in morphology. Our findings indicate that visual conditions can affect population divergence in predator populations through their effects on resource utilization.

  • 3.
    Bartels, Pia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hirsch, Philipp Emanuel
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Dissolved Organic Carbon Reduces Habitat Coupling by Top Predators in Lake Ecosystems2016In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, p. 955-967Article in journal (Refereed)
    Abstract [en]

    Increasing input of terrestrial dissolved organic carbon (DOC) has been identified as a widespread environmental phenomenon in many aquatic ecosystems. Terrestrial DOC influences basal trophic levels: it can subsidize pelagic bacterial production and impede benthic primary production via light attenuation. However, little is known about the impacts of elevated DOC concentrations on higher trophic levels, especially on top consumers. Here, we used Eurasian perch (Perca fluviatilis) to investigate the effects of increasing DOC concentrations on top predator populations. We applied stable isotope analysis and geometric morphometrics to estimate long-term resource and habitat utilization of perch. Habitat coupling, the ability to exploit littoral and pelagic resources, strongly decreased with increasing DOC concentrations due to a shift toward feeding predominantly on pelagic resources. Simultaneously, resource use and body morphology became increasingly alike for littoral and pelagic perch populations with increasing DOC, suggesting more intense competition in lakes with high DOC. Eye size of perch increased with increasing DOC concentrations, likely as a result of deteriorating visual conditions, suggesting a sensory response to environmental change. Increasing input of DOC to aquatic ecosystems is a common result of environmental change and might affect top predator populations in multiple and complex ways.

  • 4.
    Bolnick, Daniel
    et al.
    University of Texas.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Araujo, Mario
    Univ Estadual Campinas, Inst Biol, Programa Posgrad Ecol, Brazil.
    Persson, Lennart
    Umeå Universitet.
    Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous2007In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 104, no 24, p. 10075-10079Article in journal (Refereed)
    Abstract [en]

    There is extensive evidence that some species of ecological generalists, which use a wide diversity of resources, are in fact heterogeneous collections of relatively specialized individuals. This within-population variation, or "individual specialization," is a key requirement for frequency-dependent interactions that may drive a variety of types of evolutionary diversification and may influence the population dynamics and ecological interactions of species. Consequently, it is important to understand when individual specialization is likely to be strong or weak. The niche variation hypothesis (NVH) suggests that populations tend to become more generalized when they are released from interspecific competition. This niche expansion was proposed to arise via increased variation among individuals rather than increased individual niche breadth. Consequently, we expect ecological generalists to exhibit stronger individual specialization, but this correlation has been repeatedly rejected by empiricists. The drawback with previous empirical tests of the NVH is that they use morphological variation as a proxy for niche variation, ignoring the role of behavior and complex phenotype-function relationships. Here, we used diet data to directly estimate niche variation among individuals. Consistent with the NVH, we show that more generalized populations also exhibit more niche variation. This trend is quite general, appearing in all five case studies examined: three-spine stickleback, Eurasian perch, Anolis lizards, intertidal gastropods, and a community of neotropical frogs. Our results suggest that generalist populations may tend to be more ecologically variable. Whether this translates into greater genetic variation, evolvability, or ecological stability remains to be determined.

  • 5. Bolnick, D.I.
    et al.
    Snowberg, Lisa K.
    Hirsch, Philippe E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lauber, Christian L.
    Org, Elin
    Parks, Brian
    Lusis, Aldons J.
    Knight, Rob
    Caporaso, J. Gregory
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Individual diet has sex-dependent
effects on vertebrate gut microbiota2014In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, p. 4500-Article in journal (Refereed)
  • 6. Bolnick, D.I.
    et al.
    Snowberg, L.K.
    Hirsch, P.E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lauber, C.L.
    Knight, R.
    Caporaso, J.G.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Individuals’ diet diversity influences gut microbial diversity in two freshwater fish (threespine stickleback and Eurasian perch)2014In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 17, no 8, p. 979-987Article in journal (Refereed)
    Abstract [en]

    Vertebrates' diets profoundly influence the composition of symbiotic gut microbial communities. Studies documenting diet-microbiota associations typically focus on univariate or categorical diet variables. However, in nature individuals often consume diverse combinations of foods. If diet components act independently, each providing distinct microbial colonists or nutrients, we expect a positive relationship between diet diversity and microbial diversity. We tested this prediction within each of two fish species (stickleback and perch), in which individuals vary in their propensity to eat littoral or pelagic invertebrates or mixtures of both prey. Unexpectedly, in most cases individuals with more generalised diets had less diverse microbiota than dietary specialists, in both natural and laboratory populations. This negative association between diet diversity and microbial diversity was small but significant, and most apparent after accounting for complex interactions between sex, size and diet. Our results suggest that multiple diet components can interact non-additively to influence gut microbial diversity.

  • 7.
    Boughman, Janette W.
    et al.
    Michigan State Univ, Dept Integrat Biol, E Lansing, MI 48824 USA..
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Synergistic selection between ecological niche and mate preference primes diversification2017In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 71, no 1, p. 6-22Article in journal (Refereed)
    Abstract [en]

    The ecological niche and mate preferences have independently been shown to be important for the process of speciation. Here, we articulate a novel mechanism by which ecological niche use and mate preference can be linked to promote speciation. The degree to which individual niches are narrow and clustered affects the strength of divergent natural selection and population splitting. Similarly, the degree to which individual mate preferences are narrow and clustered affects the strength of divergent sexual selection and assortative mating between diverging forms. This novel perspective is inspired by the literature on ecological niches; it also explores mate preferences and how they may contribute to speciation. Unlike much comparative work, we do not search for evolutionary patterns using proxies for adaptation and sexual selection, but rather we elucidate how ideas from niche theory relate to mate preference, and how this relationship can foster speciation. Recognizing that individual and population niches are conceptually and ecologically linked to individual and population mate preference functions will significantly increase our understanding of rapid evolutionary diversification in nature. It has potential to help solve the difficult challenge of testing the role of sexual selection in the speciation process. We also identify ecological factors that are likely to affect individual niche and individual mate preference in synergistic ways and as a consequence to promote speciation. The ecological niche an individual occupies can directly affect its mate preference. Clusters of individuals with narrow, differentiated niches are likely to have narrow, differentiated mate preference functions. Our approach integrates ecological and sexual selection research to further our understanding of diversification processes. Such integration may be necessary for progress because these processes seem inextricably linked in the natural world.

  • 8. DeAngelis, Donald L.
    et al.
    Wolkowicz, Gail S. K.
    Lou, Yuan
    Jiang, Yuexin
    Novak, Mark
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Araujo, Marcio S.
    Jo, YoungSeung
    Cleary, Erin A.
    The Effect of Travel Loss on Evolutionarily Stable Distributions of Populations in Space2011In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 178, no 1, p. 15-29Article in journal (Refereed)
    Abstract [en]

    A key assumption of the ideal free distribution (IFD) is that there are no costs in moving between habitat patches. However, because many populations exhibit more or less continuous population movement between patches and traveling cost is a frequent factor, it is important to determine the effects of costs on expected population movement patterns and spatial distributions. We consider a food chain (tritrophic or bitrophic) in which one species moves between patches, with energy cost or mortality risk in movement. In the two-patch case, assuming forced movement in one direction, an evolutionarily stable strategy requires bidirectional movement, even if costs during movement are high. In the N-patch case, assuming that at least one patch is linked bidirectionally to all other patches, optimal movement rates can lead to source-sink dynamics where patches with negative growth rates are maintained by other patches with positive growth rates. As well, dispersal between patches is not balanced (even in the two-patch case), leading to a deviation from the IFD. Our results indicate that cost-associated forced movement can have important consequences for spatial metapopulation dynamics. Relevance to marine reserve design and the study of stream communities subject to drift is discussed.

  • 9.
    Eklöv, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Predation risk influences adaptive morphological variation in fish populations2006In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 167, no 3, p. 440-452Article in journal (Refereed)
    Abstract [en]

    Predators can cause a shift in both density and frequency of a prey phenotype that may lead to phenotypic divergence through natural selection. What is less investigated is that predators have a variety of indirect effects on prey that could potentially have large evolutionary responses. We conducted a pond experiment to test whether differences in predation risk in different habitats caused shifts in behavior of prey that, in turn, would affect their morphology. We also tested whether the experimental data could explain the morphological variation of perch in the natural environment. In the experiment, predators caused the prey fish to shift to the habitat with the lower predation risk. The prey specialized on habitat-specific resources, and there was a strong correlation between diet of the prey fish and morphological variation, suggesting that resource specialization ultimately affected the morphology. The lack of differences in competition and mortality suggest that the morphological variation among prey was induced by differences in predation risk among habitats. The field study demonstrated that there are differences in growth related to morphology of perch in two different habitats. Thus, a trade-off between foraging and predator avoidance could be responsible for adaptive morphological variation of young perch.

  • 10.
    Faulks, Leanne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Östman, Örjan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Genetic and morphological divergence along the littoral–pelagic axis in two common and sympatric fishes: perch, Perca fluviatilis (Percidae) and roach, Rutilus rutilus (Cyprinidae)2015In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 114, no 4, p. 929-940Article in journal (Refereed)
    Abstract [en]

    Individuals are constantly in competition with one another and, on both ecological and evolutionary timescales, processes act to reduce this competition and promote the gain of fitness advantages via diversification. Here we have investigated the genetic (AFLP) and morphological (geometric morphometrics) aspects of the littoral–pelagic axis, a commonly observed resource polymorphism in freshwater fishes of postglacial lakes. We found a large degree of variation in the genetic and morphological divergence between littoral and pelagic perch and roach across Swedish lakes. Although there was evidence of assortative mating (elevated kinship values) in both species, we could not find any significant coupling of morphology and genetic divergence. Instead, there was evidence that the extent of resource polymorphism may be largely caused by phenotypic plasticity. These results suggest that assortative mating, which can lead to genetically determined adaptive divergence, does occur in these species, particularly perch, but not according to genetically fixed morphological traits. The behavioural mechanisms facilitating associative mating need to be investigated to explore the interaction between phenotypic plasticity and adaptive genetic divergence and their roles in diversification.

  • 11.
    Faulks, Leanne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Ragnarsson-Stabo, Henrik
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Östman, Örjan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Intraspecific Niche Variation Drives Abundance-Occupancy Relationships in Freshwater Fish Communities2015In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, no 2, p. 272-283Article in journal (Refereed)
    Abstract [en]

    A positive relationship between occupancy and average local abundance of species is found in a variety of taxa, yet the mechanisms driving this association between abundance and occupancy are still enigmatic. Here we show that freshwater fishes exhibit a positive abundance-occupancy relationship across 125 Swedish lakes. For a subset of 9 species from 11 lakes, we estimated species-specific diet breadth from stable isotopes, within-lake habitat breadth from catch data for littoral and pelagic nets, adaptive potential from genetic diversity, abiotic niche position, and dispersal capacity. Average local abundance was mainly positively associated with both within-lake habitat and diet breadth, that is, species with larger intraspecific variation in niche space had higher abundances. No measure was a good predictor of occupancy, indicating that occupancy may be more directly related to abundance or abiotic conditions than to niche breadth per se. This study suggests a link between intraspecific niche variation and a positive abundance-occupancy relationship and implies that management of freshwater fish communities, whether to conserve threatened or control invasive species, should initially be aimed at niche processes.

  • 12.
    Hirsch, Philipp E
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Indirect trophic interactions with an invasive species affect phenotypic divergence in a top consumer2013In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 172, no 1, p. 245-256Article in journal (Refereed)
    Abstract [en]

    While phenotypic responses to direct species interactions are well studied, we know little about the consequences of indirect interactions for phenotypic divergence.In this study we used lakes with and without the zebra mussel to investigate effects ofindirect trophic interactions on phenotypic divergence between littoral and pelagic perch. We found a greater phenotypic divergence between littoral and pelagic individuals inlakes with zebra mussels and propose a mussel-mediated increase in pelagic and benthic resource availability as a major factor underlying this divergence. Lakes withzebra mussels contained higher densities of large plankton taxa and large invertebrates. We suggest that this augmented resource availability improved perch foraging opportunities in both the littoral and pelagic zones. Perch in both habitats could hence express a more specialized foraging morphology, leading to an increased divergence of perch forms in lakes with zebra mussels. As perch do not prey on mussels directly, we conclude that the increased divergence results from indirect interactions with the mussels. Our results hence suggest that species at lower food web levels can indirectlyaffect phenotypic divergence in species at the top of the food chain.

  • 13. Ingram, Travis
    et al.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Kraft, Nathan
    Kratina, Pavel
    Southcott, Laura
    Schluter, Dolph
    Intraguild predation drives evolutionary niche shift in threespine stickleback2012In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 6, p. 1819-1832Article in journal (Refereed)
    Abstract [en]

    Intraguild predation—competition and predation by the same antagonist—is widespread, but its evolutionary consequences are unknown. Intraguild prey may evolve antipredator defenses, superior competitive ability on shared resources, or the ability to use an alternative resource, any of which may alter the structure of the food web. We tested for evolutionary responses by threespine stickleback to a benthic intraguild predator, prickly sculpin. We used a comparative morphometric analysis to show that stickleback sympatric with sculpin are more armored and have more limnetic-like body shapes than allopatric stickleback. To test the ecological implications of this shift, we conducted a mesocosm experiment that varied sculpin presence and stickleback population of origin (from one sympatric and one allopatric lake). Predation by sculpin greatly increased the mortality of allopatric stickleback. In contrast, sculpin presence did not affect the mortality of sympatric stickleback, although they did have lower growth rates suggesting increased nonpredatory effects of sculpin. Consistent with their morphology, sympatric stickleback included more pelagic prey in their diets, leading to depletion of zooplankton in the mesocosms. These findings suggest that intraguild prey evolution has altered food web structure by reducing both predation by the intraguild predator and diet overlap between species

  • 14.
    Johansson, Frank
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Bini, L. M.
    Univ Fed Goias, Dept Ecol, BR-74001970 Goiania, Go, Brazil.
    Coiffard, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Wester, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Heino, J.
    Finnish Environm Inst, Freshwater Ctr, Paavo Havaksen Tie 3, FI-90570 Oulu, Finland.
    Environmental variables drive differences in the beta diversity of dragonfly assemblages among urban stormwater ponds2019In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 106, article id 105529Article in journal (Refereed)
    Abstract [en]

    Stormwater ponds are beneficial to urban landscapes because these man-made systems can reduce the negative effects of flooding in urban areas and restrain the distribution of pollutants. In addition, these systems are especially important to maintain the biodiversity of urban landscapes. Here, we sampled a set of 18 stormwater ponds in the city of Uppsala in Sweden to test the relationship between beta diversity of adult dragonflies and environmental factors (local and land use variables). We analysed the total beta diversity and its two components: replacement and richness difference. We recorded 31 species of Odonata, comprising 61% of the Odonata species in the province of Uppland in Sweden. By itself, this result indicates the importance of stormwater ponds in contributing to biodiversity in urban areas. The richness difference component of beta diversity was higher than the replacement component. Results from generalized dissimilarly models indicated that the richness difference component was mainly related with pond area and total vegetation cover (aquatic vegetation plus vegetation surrounding ponds). Focusing on different vegetation variables separately, models indicated that the beta diversity components were significantly correlated with percentage cover of floating algae scums, emergent aquatic macrophytes and tall shore vegetation. These results are consistent with what is known about the ecology of dragonflies, including the importance of aerial plant structures for perching, shelter from terrestrial and aquatic predators, and for providing oviposition sites. We also found that the stormwater ponds harboured a large part of the regional species pool. These systems are therefore important havens of biodiversity in urban landscapes. Our results also indicate that the management of different types of vegetation is key to maximize the potential of these systems in maintaining regional biodiversity.

  • 15.
    Marklund, Maria H. K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Habitat coupling mediates trophic cascades in an aquatic community2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 9Article in journal (Refereed)
    Abstract [en]

    Trophic cascades and other indirect effects can significantly mediate community interactions. Movement of energy between systems has been shown to be important for trophic cascades in food webs, where coupling between habitats can be important for food web stability and species evenness. To investigate the effects of habitat coupling on the stability and dynamics of chlorophyll a (used as a proxy for phytoplankton biomass), mediated by the abundance and composition of zooplankton and macroinvertebrates, we manipulated habitat use by the predator perch. We show a greater indirect effect of predation on phytoplankton abundance when no habitat coupling occurs, indicating a stronger predation effect and a decrease in zooplankton grazing pressure leading to an increase in phytoplankton biomass. Although we found a significant effect on chlorophyll a between the treatments, this effect was not evident in the abundance of prey resources of perch (zooplankton and macroinvertebrates). Other indirect effects, not measured in this study, such as compositional changes in prey groups, could potentially explain the lack of effect in prey resources. While there is a strong theoretical argument for the stabilizing effects of habitat coupling, empirical evidence is scarce. Our study offers tentative support for these theoretical predictions in a natural system.

  • 16.
    Marklund, Maria H. K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Faulks, Leanne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Sugadaira Montane Research Center, University of Tsukuba, Sugadairakogen 1278-294, Ueda, Nagano 386-2204, Japan.
    Breed, Martin F.
    School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Scharnweber, Kristin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, NKS BioClinicum, Solna, Sweden.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Asymmetrical habitat coupling of an aquatic predator: The importance of individual specialization2019In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 9, no 6, p. 3405-3415Article in journal (Refereed)
    Abstract [en]

    Predators should stabilize food webs because they can move between spatially separate habitats. However, predators adapted to forage on local resources may have a reduced ability to couple habitats. Here, we show clear asymmetry in the ability to couple habitats by Eurasian perch—a common polymorphic predator in European lakes. We sampled perch from two spatially separate habitats—pelagic and littoral zones—in Lake Erken, Sweden. Littoral perch showed stronger individual specialization, but they also used resources from the pelagic zone, indicating their ability to couple habitats. In contrast, pelagic perch showed weaker individual specialization but near complete reliance on pelagic resources, indicating their preference to one habitat. This asymmetry in the habitat coupling ability of perch challenges the expectation that, in general, predators should stabilize spatially separated food webs. Our results suggest that habitat coupling might be constrained by morphological adaptations, which in this case were not related to genetic differentiation but were more likely related to differences in individual specialization.

  • 17.
    Marklund, Maria H. K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Water Research Centre and The Environment Institute, School of Biological Sciences, Univ. of Adelaide, North Terrace, SA, Australia.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Scharnweber, Kristin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    The influence of habitat accessibility on the dietary and morphological specialisation of an aquatic predator2018In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 127, no 1, p. 160-169Article in journal (Refereed)
    Abstract [en]

    Individual diet and habitat specialisation are widespread in animal taxa and often related to levels of predation and competition. Mobile consumers such as predatory fish can stabilise lake food webs by ranging over a larger area than their prey, thereby switching between habitats. Although, this switching assumes that the predator has equal preference for the available prey, individual diet specialisation and morphological adaptations to different habitats could potentially prevent individuals from switching between habitats. In this study, we assessed the niche width and individual specialisation in Eurasian perch Perca fluviatilis in response to a shift in habitat use by manipulating the ability for this top predator to couple habitats. We ran an eight weeks pond experiment, to test the effect of habitat switching on diet and morphological specialisations. We show that habitat coupling influenced individual diet specialisation and niche use in expected directions where specialisation increased with decreasing habitat switching. In contrast to expectations, the morphological variation decreased with increasing diet specialisation. Our results expand on previous work and suggest that individual specialisation and niche width can impact the ability of mobile predators to couple habitats. Furthermore, it shows the importance of individual specialisations in relation to habitat coupling.

  • 18.
    Miller, Elizabeth Theresa
    et al.
    Univ Oregon, Inst Ecol & Evolut, Eugene, OR USA.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Bohannan, Brendan J. M.
    Univ Oregon, Inst Ecol & Evolut, Eugene, OR USA.
    Microbiomes as Metacommunities: Understanding Host-Associated Microbes through Metacommunity Ecology2018In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 33, no 12, p. 926-935Article, review/survey (Refereed)
    Abstract [en]

    Interest in host-associated microbiomes has skyrocketed recently, yet our ability to explain microbiome variation has remained stubbornly low. Considering scales of interaction beyond the level of the individual host could lead to new insights. Metacommunity theory has many of the tools necessary for modeling multiscale processes and has been successfully applied to host microbiomes. However, the biotic nature of the host requires an expansion of theory to incorporate feedback between the habitat patch (host) and their local (microbial) community. This feedback can have unexpected effects, is predicted to be common, and can arise through a variety of mechanisms, including developmental, ecological, and evolutionary processes. We propose a new way forward for both metacommunity theory and host microbiome research that incorporates this feedback.

  • 19. Nonaka, E.
    et al.
    Brännström, R.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Assortative mating can limit the evolution of phenotypic plasticity2014In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 28, no 6, p. 1057-1074Article in journal (Refereed)
    Abstract [en]

    Phenotypic plasticity, the ability to adjust phenotype to the exposed environment, is often advantageous for organisms living in heterogeneous environments. Although the degree of plasticity appears limited in nature, many studies have reported low costs of plasticity in various species. Existing studies argue for ecological, genetic, or physiological costs or selection eliminating plasticity with high costs, but have not considered costs arising from sexual selection. Here, we show that sexual selection caused by mate choice can impede the evolution of phenotypic plasticity in a trait used for mate choice. Plasticity can remain low to moderate even in the absence of physiological or genetic costs, when individuals phenotypically adapted to contrasting environments through plasticity can mate with each other and choose mates based on phenotypic similarity. Because the non-choosy sex (i.e., males) with lower degrees of plasticity are more favored in matings by the choosy sex (i.e., females) adapted to different environments, directional selection toward higher degrees of plasticity is constrained by sexual selection. This occurs at intermediate strengths of female choosiness in the range of the parameter value we examined. Our results demonstrate that mate choice is a potential source of an indirect cost to phenotypic plasticity in a sexually selected plastic trait.

  • 20.
    Nonaka, Etsuko
    et al.
    Umea Univ, Dept Ecol & Environm Sci, S-90187 Umea, Sweden.;Univ Helsinki, Dept Biosci, Metapopulat Res Ctr, FI-00014 Helsinki, Finland..
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Thibert-Plante, Xavier
    Umea Univ, Dept Ecol & Environm Sci, S-90187 Umea, Sweden..
    Englund, Goran
    Umea Univ, Dept Ecol & Environm Sci, S-90187 Umea, Sweden..
    Brännström, Åke
    Umea Univ, Dept Math & Math Stat, S-90187 Umea, Sweden.;Int Inst Appl Syst Anal, Evolut & Ecol Program, A-2361 Laxenburg, Austria..
    Mechanisms by Which Phenotypic Plasticity Affects Adaptive Divergence and Ecological Speciation2015In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, no 5, p. E126-E143Article in journal (Refereed)
    Abstract [en]

    Phenotypic plasticity is the ability of one genotype to produce different phenotypes depending on environmental conditions. Several conceptual models emphasize the role of plasticity in promoting reproductive isolation and, ultimately, speciation in populations that forage on two or more resources. These models predict that plasticity plays a critical role in the early stages of speciation, prior to genetic divergence, by facilitating fast phenotypic divergence. The ability to plastically express alternative phenotypes may, however, interfere with the early phase of the formation of reproductive barriers, especially in the absence of geographic barriers. Here, we quantitatively investigate mechanisms under which plasticity can influence progress toward adaptive genetic diversification and ecological speciation. We use a stochastic, individual based model of a predator-prey system incorporating sexual reproduction and mate choice in the predator. Our results show that evolving plasticity promotes the evolution of reproductive isolation under diversifying environments when individuals are able to correctly select a more profitable habitat with respect to their phenotypes (i.e., adaptive habitat choice) and to assortatively mate with relatively similar phenotypes. On the other hand, plasticity facilitates the evolution of plastic generalists when individuals have a limited capacity for adaptive habitat choice. We conclude that plasticity can accelerate the evolution of a reproductive barrier toward adaptive diversification and ecological speciation through enhanced phenotypic differentiation between diverging phenotypes.

  • 21.
    Olsson, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Quevedo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Colson, Celine
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Gut length plasticity in perch: Into the bowels of resource polymorphisms2007In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 90, no 3, p. 517-523Article in journal (Refereed)
    Abstract [en]

    Resource polymorphisms, intraspecific variation in morphology due to differential resource use, are common across a wide range of animal taxa. The focus in studies of such polymorphisms has been on external morphology, but the differential use of food resources could also influence other phenotypic traits such as the digestive performance. In the present study, we experimentally demonstrate that Eurasian perch (Perca fluviatilis L.) display adaptive plasticity in gut length when exposed to different food types. Perch fed a less digestible food type developed relatively longer guts compared to fish fed a more easily digested food type. This divergence in gut length was also apparent under natural conditions because perch inhabiting the littoral and pelagic habitats of a lake differed in resource use and relative gut length. Despite that the digestive system in perch is plastic, we found that individuals switching to a novel food type might experience an initial fitness cost of the diet switch in the form of a temporary reduction in body condition. These results show the importance of gut length plasticity for an ontogenetic omnivore but also a cost that might prevent diet switching in polymorphic populations.

  • 22.
    Olsson, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Effects of resource level and habitat type on behavioural and morphological plasticity in Eurasian perch2007In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 152, no 1, p. 48-56Article in journal (Refereed)
    Abstract [en]

    Spatial and temporal heterogeneity in the environment is a common feature affecting many natural populations. For example, both the resource levels and optimal habitat choices of individuals likely change over time. One way for organisms to cope with environmental variation is to display adaptive plasticity in traits such as behavior and morphology. Since trait plasticity is hypothesized to be a prerequisite for character divergence, studies of mechanisms behind such plasticity are warranted. In this study, we looked at the interaction of two potentially important environmental variables on behavioral and morphological plasticity in Eurasian perch (Perca fluviatilis L.). More specifically, the plastic responses in activity and morphology of perch exposed to different resource levels and simulated habitat types were studied in an aquarium experiment. The resource level experienced had a large influence on plasticity in both activity and morphology. Behavioral adaptations have been thought to mediate morphological transitions, and we suggest that the morphological response to the resource level was mediated by differences in activity and growth rates. The habitat type also affected morphological plasticity but to a lesser extent, and there was no effect on activity from habitat type. Based on these results, we suggest that it is essential to include several environmental factors acting in concert when studying mechanisms behind trait plasticity. We also propose that variation in resource levels might play a key role in fostering trait plasticity in at least fish populations, while other environmental variables such as divergent habitat complexities and prey types might be less influential. Dynamics in resource levels and optimal habitat choices might thus be important factors influencing character divergence in natural populations.

  • 23.
    Olsson, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Growth rate constrain morphological divergence when driven by competition2006In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 115, no 1, p. 15-22Article in journal (Refereed)
    Abstract [en]

    Resource competition has been hypothesized to be important in driving divergence by natural selection. The effect of competition on morphological divergence and plasticity has however rarely been investigated. Since low growth rates might constrain morphological modulation and individual growth rates usually are negatively related to the intensity of competition, there might be a connection between competition, growth rate and morphological divergence. We performed an aquarium experiment with young-of-the-year Eurasian perch (Perca fluviatilis L.) to investigate how individual growth rate affected morphological plasticity induced by contrasting habitat treatments. Furthermore, in a field study of 10 lakes we also related the degree of morphological differentiation between habitats to the intraspecific competitior biomass. In the aquarium experiment we found that morphological plasticity was growth rate dependent in that morphological differentiation between the habitat treatments was confined to high individual growth rates. In the field study we found that morphological differentiation between habitats decreased with increasing intraspecific competitior biomass. Since plasticity is hypothesized to be important in divergence and intraspecific biomass could serve as a proxy for the level of competition, we suggest that our results indicate that morphological divergence might be constrained during periods of intense intraspecific competition due to low growth rates. A possible scenario is that at low growth rates all energy available is used for metabolic maintenance and no surplus energy is therefore available for morphological modulation.

  • 24.
    Persson, Lennart
    et al.
    Department of Ecology and Environmental Science, Umeå University.
    Claessen, David
    Department of Ecology and Environmental Science, Umeå University.
    M. De Roos, André
    Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam.
    Byström, Pär
    Department of Ecology and Environmental Science, Umeå University.
    Sjögren, Stefan
    Department of Ecology and Environmental Science, Umeå University.
    Svanbäck, Richard
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Wahlström, Eva
    Department of Ecology and Environmental Science, Umeå University.
    Westmana, Erika
    Department of Ecology and Environmental Science, Umeå University.
    Cannibalism in a size-structured population: energy extraction and control2004In: Ecological Monographs, ISSN 0012-9615, E-ISSN 1557-7015, Vol. 74, no 1, p. 135-157Article in journal (Refereed)
    Abstract [en]

    Recent size-structured cannibalistic models point to the importance of the energy gain by cannibals and also show that this gain may result in the emergence of giant individuals. We use a combination of a 10-year field study of a perch (Perca fluviatilis) population and quantitative within-season modeling of individual and population-level dynamics to investigate which mechanisms are most likely to drive the dynamics of the studied perch population. We focused on three main aspects to explain observed discrepancies between earlier model predictions and data: (1) introduction of more than one shared resource between cannibals and victims, (2) whether or not several victim age cohorts are necessary to allow giant growth, and (3) the intensity of inter-cohort competition between young-of-the-year (YOY) perch and 1-yr-old perch.

    At the start of the study period, the perch population was dominated by “stunted” perch individuals, and recruitment of perch to an age of 1-yr-old was negligible. Following a major death in adult perch, strong recruitments of perch to 1-yr-old were thereafter observed for a number of years. As 1-yr-olds these successful recruiters subsequently starved to death due to competition with the new YOY. The few surviving adult perch accelerated substantially in growth and became “giants.” At the end of the study period, the perch population moved back to the situation with stunted individuals. There was a high agreement between observed diets of cannibalistic perch and those predicted by the model for both the stunted and the giant phases. Analyses of growth rates showed that cannibalistic perch could become giants on a diet of YOY perch only, but that a supplement with the second shared resource (macroinvertebrates) was needed to reach the observed sizes. Modeling of growth and diet in the giant phase showed an exploitative competitive effect of YOY perch on 1-yr-old perch, but a restriction in habitat use of 1-yr-old perch had to be assumed to yield the observed growth rate and diet. The resource dynamics of zooplankton and macroinvertebrates were both accurately predicted by the model. Also, YOY perch mortality was accurately predicted and, furthermore, suggested that one of the trawling methods used may underestimate the number of YOY perch when they increase in size.

    We conclude that the presence of a second shared resource and the restricted habitat use and absence of cannibalistic consumption by 1-yr-old perch individuals are two important mechanisms to explain the discrepancy between model predictions and data. Our results also point to the fact that that the dynamics observed may be explained by complex dynamics not involving the presence of a giant and dwarf cycle.

  • 25.
    Quevedo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Intrapopulation niche partitioning in a generalist predator limits food web connectivity2009In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 90, no 8, p. 2263-2274Article in journal (Refereed)
    Abstract [en]

    Predators are increasingly recognized as key elements in food webs because of their ability to link the fluxes of nutrients and energy between spatially separated food chains. However, in the context of food web connectivity, predator populations have been mainly treated as homogeneous units, despite compelling evidence of individual specialization in resource use. It is conceivable that individuals of a predatory species use different resources associated with spatially separated food chains, thereby decoupling cross-habitat linkages. We tested whether intrapopulation differences in habitat use in the generalist freshwater predator Eurasian perch (Perca fluviatilis) led to long-term niche partitioning and affected the degree of ecological habitat coupling. We evaluated trophic niche variability at successively larger timescales by analyzing gut contents and stable isotopes (δ13C and δ15N) in liver and muscle, tissues that provide successively longer integration of trophic activity. We found that the use of distinct habitats in perch led to intrapopulation niche partitioning between pelagic and littoral subpopulations, consistent through the various timescales. Pelagic fish showed a narrower niche, lower individual specialization, and more stable trophic behavior than littoral fish, as could be expected from inhabiting a relatively less diverse environment. This result indicated that substantial niche reduction could occur in a generalist predator at the subpopulation level, consistent with the use of a habitat that provides fewer chances of individual specialization. We showed that intrapopulation niche partitioning limits the ability of individual predators to link spatially separated food chains. In addition, we suggest a quantitative, standardized approach based on stable isotopes to measure the degree of habitat coupling mediated by a top predator.

  • 26.
    Skulason, Skuli
    et al.
    Holar Univ, Dept Aquaculture & Fish Biol, IS-551 Sauoarkrokur, Iceland;Iceland Museum Nat Hist, Brynjolfsgata 5, IS-107 Reykjavik, Iceland.
    Parsons, Kevin J.
    Univ Glasgow, Inst Biodivers Anim Hlth & Comparat Med, Glasgow G12 8QQ, Lanark, Scotland.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rasanen, Katja
    EAWAG, Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Ueberlandstr 133, CH-8600 Dubendorf, Switzerland;Swiss Fed Inst Technol, Inst Integrat Biol, Ueberlandstr 133, CH-8600 Dubendorf, Switzerland.
    Ferguson, Moira M.
    Univ Guelph, Dept Integrat Biol, Guelph, ON N1G 2W1, Canada.
    Adams, Colin E.
    Univ Glasgow, Scottish Ctr Ecol & Nat Environm, IBAHCM, Glasgow G12 8QQ, Lanark, Scotland.
    Amundsen, Per-Arne
    Univ Tromso, Freshwater Ecol Grp, Dept Arctic & Marine Biol, Fac Biosci Fisheries & Econ, N-9037 Tromso, Norway.
    Bartels, Pia
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden.
    Bean, Colin W.
    Scottish Nat Heritage, Caspian House,Clydebank Business Pk, Clydebank G81 2NR, Scotland.
    Boughman, Janette W.
    Michigan State Univ, Dept Integrat Biol, E Lansing, MI 48824 USA.
    Englund, Goeran
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden.
    Gudbrandsson, Johannes
    Univ Iceland, Inst Life & Environm Sci, IS-101 Reykjavik, Iceland.
    Hooker, Oliver E.
    PR Stat LTD, 53 Morrison St, Glasgow G5 8LB, Lanark, Scotland.
    Hudson, Alan G.
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden.
    Kahilainen, Kimmo K.
    Inland Norway Univ Appl Sci, Dept Forestry & Wildlife Management, Campus Evenstad,Anne Evenstadvei 80, NO-2480 Koppang, Norway.
    Knudsen, Rune
    Univ Tromso, Freshwater Ecol Grp, Dept Arctic & Marine Biol, Fac Biosci Fisheries & Econ, N-9037 Tromso, Norway.
    Kristjansson, Bjarni K.
    Holar Univ, Dept Aquaculture & Fish Biol, IS-551 Sauoarkrokur, Iceland.
    Leblanc, Camille A-L.
    Holar Univ, Dept Aquaculture & Fish Biol, IS-551 Sauoarkrokur, Iceland.
    Jonsson, Zophonias
    Univ Iceland, Inst Life & Environm Sci, IS-101 Reykjavik, Iceland.
    Ohlund, Gunnar
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden.
    Smith, Carl
    Univ St Andrews, Sch Biol, St Andrews KY16 9AJ, Fife, Scotland.
    Snorrason, Sigurdur S.
    Univ Iceland, Inst Life & Environm Sci, IS-101 Reykjavik, Iceland.
    A way forward with eco evo devo: an extended theory of resource polymorphism with postglacial fishes as model systems2019In: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 94, no 5, p. 1786-1808Article in journal (Refereed)
    Abstract [en]

    A major goal of evolutionary science is to understand how biological diversity is generated and altered. Despite considerable advances, we still have limited insight into how phenotypic variation arises and is sorted by natural selection. Here we argue that an integrated view, which merges ecology, evolution and developmental biology (eco evo devo) on an equal footing, is needed to understand the multifaceted role of the environment in simultaneously determining the development of the phenotype and the nature of the selective environment, and how organisms in turn affect the environment through eco evo and eco devo feedbacks. To illustrate the usefulness of an integrated eco evo devo perspective, we connect it with the theory of resource polymorphism (i.e. the phenotypic and genetic diversification that occurs in response to variation in available resources). In so doing, we highlight fishes from recently glaciated freshwater systems as exceptionally well-suited model systems for testing predictions of an eco evo devo framework in studies of diversification. Studies on these fishes show that intraspecific diversity can evolve rapidly, and that this process is jointly facilitated by (i) the availability of diverse environments promoting divergent natural selection; (ii) dynamic developmental processes sensitive to environmental and genetic signals; and (iii) eco evo and eco devo feedbacks influencing the selective and developmental environments of the phenotype. We highlight empirical examples and present a conceptual model for the generation of resource polymorphism - emphasizing eco evo devo, and identify current gaps in knowledge.

  • 27.
    Svanbäck, R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Bolnick, D.I.
    Food specialization.2008In: Encyclopedia of Ecology: Vol. 2 D-F, 2008, p. 1636-1642Chapter in book (Other (popular science, discussion, etc.))
  • 28.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Bolnick, Daniel
    Univ Texas, Sect Integrat Biol, Austin, USA.
    Intraspecific competition drives increased resource use diversity within a natural population2007In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 274, no 1611, p. 839-844Article in journal (Refereed)
    Abstract [en]

    Resource competition is thought to play a major role in driving evolutionary diversification. For instance, in ecological character displacement, coexisting species evolve to use different resources, reducing the effects of interspecific competition. It is thought that a similar diversifying effect might occur in response to competition among members of a single species. Individuals may mitigate the effects of intraspecific competition by switching to use alternative resources not used by conspecific competitors. This diversification is the driving force in some models of sympatric speciation, but has not been demonstrated in natural populations. Here, we present experimental evidence confirming that competition drives ecological diversification within natural populations. We manipulated population density of three-spine sticklebacks (Gasterosteus aculeatus) in enclosures in a natural lake. Increased population density led to reduced prey availability, causing individuals to add alternative prey types to their diet. Since phenotypically different individuals added different alternative prey, diet variation among individuals increased relative to low-density control enclosures. Competition also increased the diet-morphology correlations, so that the frequency-dependent interactions were stronger in high competition. These results not only confirm that resource competition promotes niche variation within populations, but also show that this increased diversity can arise via behavioural plasticity alone, without the evolutionary changes commonly assumed by theory.

  • 29.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eklov, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Catch me if you can: Predation affetcs divergence in a polyphenic species2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 12, p. 3515-3526Article in journal (Refereed)
    Abstract [en]

    Predation is a major driving force in evolution. Predation has been shown to select for size, morphology, and camouflage. Many animals use camouflage to reduce predation risk. In some cases, individuals can adjust their pigmentation, enabling them a higher survival in a heterogeneous environment. Here, we show that the difference in pigmentation between juvenile perch individuals (Perca fluvuiatilis) occupying different environments (open water and vegetated habitats of lakes) is likely a consequence of predator selection. Lightly pigmented individuals have a higher chance of survival in open water whereas darker pigmented individuals survive better in vegetation. As a response to predators, individuals forced into the vegetation by predators developed darker skin whereas the skin of individuals forced into open water became lighter. In a common garden experiment, in the absence of predation, we found that pigmentation in juvenile perch is only due to plasticity and not to genetic variation. However, contrary to predictions, individuals raised in open water developed darker skin compared to individuals raised in vegetation. This may be a response to UV-stress. Overall, our results suggest that predation can be a strong selective agent on pigmentation differences among conspecifics occupying different habitats.

  • 30.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Effects of habitat and food resources on morphology and ontogenetic growth trajectories in perch.2002In: Oecologia 131: 61-70., Vol. 131, p. 61-70Article in journal (Refereed)
  • 31.
    Svanbäck, Richard
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Genetic variation and phenotypic plasticity: causes of morphological variation in Eurasian perch2006In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 8, no 1, p. 37-49Article in journal (Refereed)
    Abstract [en]

    Question: What is the importance of genetic variation and phenotypic plasticity in formingthe morphological difference between littoral and pelagic perch?

    Organism: Juveniles of Eurasian perch (Perca fluviatilis L.).

    Site: Enclosures (2 × 2 m) in a pond, Röbäcksdalen, Umeå, Sweden.

    Methods: Adults from the littoral and pelagic habitats were bred separately andtheir offspring were raised in enclosures with either open water or vegetation in an artificialpond.

    Results: Offspring from littoral parents had a higher proportion of littoral prey types in theirdiet than pelagic offspring even though there were no differences in prey community betweentreatments. Littoral offspring had a deeper body than pelagic offspring raised in the sameenvironment. However, most of the phenotypic variation in this experiment was explained byphenotypic plasticity: offspring from both parental types raised in open water displayedpelagic-type characteristics, whereas offspring raised in vegetation displayed littoral-typecharacteristics.

    Conclusion: Previous long-term studies on perch show that they experience a fluctuatingenvironment due to population dynamics. The plasticity in perch could therefore be importantas fluctuating environments favour plasticity.

  • 32.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Morphology dependent foraging efficiency in perch: a trade-off for ecological specialization?2003In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 102, no 2, p. 273-284Article in journal (Refereed)
    Abstract [en]

    Trade-offs in foraging efficiency leading to divergent natural selection between and within populations exploiting different resources are thought to be a primary cause of trophic polymorphism. In this study we focused on the trade-offs in foraging efficiency and growth in a polymorphic perch population. Specifically, we related habitat-specific growth and diet of perch to perch morphology. In a subsequent laboratory study we experimentally tested the trade-off by testing the efficiency of perch with different morphology feeding on pelagic (Daphnia sp., Chaoborus sp.) and littoral (mayfly larvae) food resources. The feeding performance was tested in different physical environments to see if we could predict growth patterns in the field based on foraging rate and behavior of perch.

    In the field study, we found that the perch from the littoral and the pelagic zones differed in both morphology and diet. Within the littoral zone the deeper-bodied individuals grew faster compared to the more streamlined individuals, whereas the opposite pattern was found in the pelagic zone. In the aquarium experiments, perch from the littoral zone had higher capture rates on the pelagic prey types in vegetation trials and on mayfly larvae in both open water and vegetation trials. The pelagic perch had higher capture rates on the pelagic prey types in open water trials. The littoral perch had lower search velocity than the pelagic perch in open water trials whereas the opposite pattern was found in vegetation trials. The attack velocity of the pelagic perch was also higher than that of the littoral perch independent of vegetation structure. Our results suggest that there is a functional trade-off between performance in alternate habitats and general body form in perch. Such trade-offs may promote divergent natural selection and could be the mechanism that give rise to and upholds the pattern in the field.

  • 33.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Morphology in perch affects habitat specific feeding efficiency2004In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 18, no 4, p. 503-510Article in journal (Refereed)
    Abstract [en]

    1. Trophic polymorphism is a common phenomenon in many species. Trade-offs in foraging efficiency on different resources are thought to be a primary cause of such polymorphism.

    2. To test for a trade-off in foraging efficiency perch (Perca fluviatilis L.) were used from a population that differs in morphology between the littoral and pelagic habitat of a lake. Indoor aquarium experiments were performed with three different prey types in two different environments. It was predicted that the morphology of the individual would affect foraging efficiency in the different environments and on the different prey types through search and attack behaviour.

    3. Overall the foraging efficiency of perch was found to be related to individual morphology. A connection was also found between individual morphology and search and attack behaviour. Search behaviour but not attack behaviour was affected by the structure in the aquaria. Furthermore our results show that there are relations between search behaviour and detection rates and between attack behaviour and attack success.

    4. Our results give a mechanistic explanation for the differences in foraging efficiency between littoral and pelagic perch. These differences are probably driven by a functional trade-off between foraging performance and general body form.

  • 34.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Fransson, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Holmgren, Kerstin
    Intra-specific competition drives multiple species trophic polymorphism in fish communities2008In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 117, no 1, p. 114-124Article in journal (Refereed)
    Abstract [en]

    It has been hypothesized that inter-specific competition will reduce species niche utilization and drive morphological evolution in character displacement. In the absence of a competitor, intra-specific competition may favor an expansion of the species niche and drive morphological evolution in character release. Despite of this theoretical framework, we sometimes find potential competitor species using the same niche range without any partitioning in niche. We used a database on test fishing in Sweden to evaluate the factors (inter- and intraspecific competition, predation, and abiotic factors) that could influence habitat choice of two competitor species. The pattern from the database shows that the occurrence of perch and roach occupying both littoral and pelagic habitats of lakes in Sweden is a general phenomenon. Furthermore, the results from the database suggest that this pattern is due to intra-specific competition rather than inter-specific competition or predation. In a field study, we estimated the morphological variation in perch and roach and found that, individuals of both species caught in the littoral zone were more deeper bodied compared to individuals caught in the pelagic zone. Pelagic perch fed more on zooplankton compared to littoral perch, independent of size, whereas the littoral perch had more macroinvertebrates and fish in their diet. Pelagic roach fed more on zooplankton compared to littoral roach, whereas littoral individuals fed more on plant material. Furthermore, we sampled littoral and pelagic fish from another lake to evaluate the generality of our first results and found the same habitat associated morphology in both perch and roach. The results show a consistent multi-species morphological separation in the littoral and pelagic habitats. This study suggests that intra-specific competition is possibly more important than inter-specific competition for the morphological pattern in the perch-roach system.

  • 35.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Predation selects for smaller eye size in a vertebrate: effects of environmental conditions and sex2019In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 286, no 1897, article id 20182625Article in journal (Refereed)
    Abstract [en]

    Increased eye size in animals results in a larger retinal image and thus improves visual acuity. Thus, larger eyes should aid both in finding food as well as detecting predators. On the other hand, eyes are usually very conspicuous and several studies have suggested that eye size is associated with predation risk. However, experimental evidence is scant. In this study, we address how predation affects variation in eye size by performing two experiments using Eurasian perch juveniles as prey and either larger perch or pike as predators. First, we used large outdoor tanks to compare selection due to predators on relative eye size in open and artificial vegetated habitats. Second, we studied the effects of both predation risk and resource levels on phenotypic plasticity in relative eye size in indoor aquaria experiments. In the first experiment, we found that habitat altered selection due to predators, since predators selected for smaller eye size in a non-vegetated habitat, but not in a vegetated habitat. In the plasticity experiment, we found that fish predators induced smaller eye size in males, but not in females, while resource levels had no effect on eye size plasticity. Our experiments provide evidence that predation risk could be one of the driving factors behind variation in eye size within species.

  • 36.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Persson, Lennart
    Department of Ecology and Environmental Science, Umeå University.
    Individual diet specialization, niche width and population dynamics: implications for trophic polymorphisms2004In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 73, no 5, p. 973-982Article in journal (Refereed)
    Abstract [en]

    1. We studied a perch Perca fluviatilis L. population that during a 9-year period switched between a phase of dominance of adult perch and a phase dominated by juvenile perch driven by cannibalism and intercohort competition. We investigated the effects of these population fluctuations on individual diet specialization and the mechanisms behind this specialization.

    2. Due to cannibalism, the survival of young-of-the-year (YOY) perch was much lower when adult perch density was high than when adult perch density was low.

    3. Both the individual niche breadth (if weighed for resource encounter) and the population niche breadth were highest when adult population density was high and, consequently, individual specialization was highest at high adult perch densities.

    4. When adult perch density was low, the abundances of benthic invertebrate and YOY perch were high and dominated the diet of adult perch, whereas the density of zooplankton was low due to predation from YOY perch. At high perch densities, benthic invertebrate abundance was lower and zooplankton level was higher and some perch switched to feed on zooplankton.

    5. Our results show that individual specialization may fluctuate with population density through feedback mechanisms via resource levels. Such fluctuations may have profound implications on the evolution of resource polymorphisms

  • 37.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Persson, Lennart
    Population density fluctuations change the selection gradient in Eurasian perch2009In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 173, no 4, p. 507-516Article in journal (Refereed)
    Abstract [en]

    A high degree of trophic polymorphism has been associated with the absence of high variability in population density. An explanation for this pattern is that density fluctuations may influence selective regime forms in populations. Still, only few studies have investigated evolutionary dynamics in fluctuating populations. Here we report on a multiyear study of the Eurasian perch, wherein the fitness landscape shifts between stabilizing and directional selection at low density to disruptive selection at high density. Intrinsically driven population fluctuations is the mechanism that most likely explains these shifts in fitness landscape. Stable isotope data showed that the habitat choices of perch were stable over the growing season, indicating that the selection pressure observed each year influenced the fitness of perch in the following year’s reproductive period. Furthermore, the morphological differences between perch caught in the two habitats (littoral and pelagic) were more pronounced at high density than at low density. This study shows that an explicit consideration of population dynamics may be essential to explain the long‐term evolutionary dynamics in populations. In particular, fluctuating population dynamics may be one explanation for why not all polymorphic populations lead to speciation. Instead, fluctuating population dynamics may favor the evolution of phenotypic plasticity.

  • 38.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pineda-Krch, Mario
    Doebeli, Michael
    Fluctuating population dynamics promotes the evolution of phenotypic plasticity2009In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 174, no 2, p. 176-189Article in journal (Refereed)
    Abstract [en]

    Theoretical and empirical studies are showing evidence in support of evolutionary branching and sympatric speciation due to frequency‐dependent competition. However, phenotypic diversification due to underlying genetic diversification is only one possible evolutionary response to disruptive selection. Another potentially general response is phenotypic diversification in the form of phenotypic plasticity. It has been suggested that genetic variation is favored in stable environments, whereas phenotypic plasticity is favored in unstable and fluctuating environments. We investigate the “competition” between the processes of evolutionary branching and the evolution of phenotypic plasticity in a predator‐prey model that allows both processes to occur. In this model, environmental fluctuations can be caused by complicated population dynamics. We found that the evolution of phenotypic plasticity was generally more likely than evolutionary branching when the ecological dynamics exhibited pronounced predator‐prey cycles, whereas the opposite was true when the ecological dynamics was more stable. At intermediate levels of density cycling, trimorphisms with two specialist branches and a phenotypically plastic generalist branch sometimes occurred. Our theoretical results suggest that ecological dynamics and evolutionary dynamics can often be tightly linked and that an explicit consideration of population dynamics may be essential to explain the evolutionary dynamics of diversification in natural populations.

     

  • 39.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Quevedo, Mario
    Olsson, Jens
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Individuals in food webs: the relationships between trophic position, omnivory and among-individual diet variation2015In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 178, no 1, p. 103-114Article in journal (Refereed)
    Abstract [en]

    Among-individual diet variation is common in natural populations and may occur at any trophic level within a food web. Yet, little is known about its variation among trophic levels and how such variation could affect phenotypic divergence within populations. In this study we investigate the relationships between trophic position (the population’s range and average) and among-individual diet variation. We test for diet variation among individuals and across size classes of Eurasian perch (Perca fluviatilis), a widespread predatory freshwater fish that undergoes ontogenetic niche shifts. Second, we investigate among-individual diet variation within fish and invertebrate populations in two different lake communities using stable isotopes. Third, we test potential evolutionary implications of population trophic position by assessing the relationship between the proportion of piscivorous perch (populations of higher trophic position) and the degree of phenotypic divergence between littoral and pelagic perch sub-populations. We show that among-individual diet variation is highest at intermediate trophic positions, and that this high degree of among-individual variation likely causes an increase in the range of trophic positions among individuals. We also found that phenotypic divergence was negatively related to trophic position in a population. This study thus shows that trophic position is related to and may be important for among-individual diet variation as well as to phenotypic divergence within populations.

  • 40.
    Svanbäck, Richard
    et al.
    Biodiversity Research Centre and Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
    Schluter, Dolph
    Biodiversity Research Centre and Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
    Niche Specialization Influences Adaptive Phenotypic Plasticity in the Threespine Stickleback2012In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 180, no 1, p. 50-59Article in journal (Refereed)
    Abstract [en]

    Phenotypic plasticity may be favored in generalist populations if it increases niche width, even in temporally constant environments. Phenotypic plasticity can increase the frequency of extreme phenotypes in a population and thus allow it to make use of a wide resource spectrum. Here we test the prediction that generalist populations should be more plastic than specialists. In a common-garden experiment, we show that solitary, generalist populations of threespine sticklebacks inhabiting small coastal lakes of British Columbia have a higher degree of morphological plasticity than the more specialized sympatric limnetic and benthic species. The ancestral marine stickleback showed low levels of plasticity similar to those of sympatric sticklebacks, implying that the greater plasticity of the generalist population has evolved recently. Measurements of wild populations show that those with mean trait values intermediate between the benthic and limnetic values indeed have higher morphological variation. Our data indicate that plasticity can evolve rapidly after colonization of a new environment in response to changing niche use.

  • 41.
    Svanbäck, Richard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Brönmark, Christer
    Aquatic Ecology, Department of Biology, Lund University, Lund, Sweden..
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    The interaction between predation risk and food ration on behavior and morphology of Eurasian perch2017In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 7, no 20, p. 8567-8577Article in journal (Refereed)
    Abstract [en]

    The risk of both predation and food level has been shown to affect phenotypic development of organisms. However, these two factors also influence animal behavior that in turn may influence phenotypic development. Hence, it might be difficult to disentangle the behavioral effect from the predator or resource-level effects. This is because the presence of predators and high resource levels usually results in a lower activity, which in turn affects energy expenditure that is used for development and growth. It is therefore necessary to study how behavior interacts with changes in body shape with regard to resource density and predators. Here, we use the classic predator-induced morphological defense in fish to study the interaction between predator cues, resource availability, and behavioral activity with the aim to determine their relative contribution to changes in body shape. We show that all three variables, the presence of a predator, food level, and activity, both additively and interactively, affected the body shape of perch. In general, the presence of predators, lower swimming activity, and higher food levels induced a deep body shape, with predation and behavior having similar effect and food treatment the smallest effect. The shape changes seemed to be mediated by changes in growth rate as body condition showed a similar effect as shape with regard to food-level and predator treatments. Our results suggests that shape changes in animals to one environmental factor, for example, predation risk, can be context dependent, and depend on food levels or behavioral responses. Theoretical and empirical studies should further explore how this context dependence affects fitness components such as resource gain and mortality and their implications for population dynamics.

  • 42.
    van Dorst, Renee M.
    et al.
    Swedish Univ Agr Sci, Inst Coastal Res, Dept Aquat Resources, Oregrund, Sweden.
    Gårdmark, Anna
    Swedish Univ Agr Sci, Dept Aquat Resources, Oregrund, Sweden.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Beier, Ulrika
    Swedish Univ Agr Sci, Inst Freshwater Res, Dept Aquat Resources, Drottningholm, Sweden;Wageningen Marine Res, Ijmuiden, Netherlands.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Huss, Magnus
    Swedish Univ Agr Sci, Dept Aquat Resources, Oregrund, Sweden.
    Warmer and browner waters decrease fish biomass production2019In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 25, no 4, p. 1395-1408Article in journal (Refereed)
    Abstract [en]

    Climate change studies have long focused on effects of increasing temperatures, often without considering other simultaneously occurring environmental changes, such as browning of waters. Resolving how the combination of warming and browning of aquatic ecosystems affects fish biomass production is essential for future ecosystem functioning, fisheries, and food security. In this study, we analyzed individual- and population-level fish data from 52 temperate and boreal lakes in Northern Europe, covering large gradients in water temperature and color (absorbance, 420 nm). We show that fish (Eurasian perch, Perca fluviatilis) biomass production decreased with both high water temperatures and brown water color, being lowest in warm and brown lakes. However, while both high temperature and brown water decreased fish biomass production, the mechanisms behind the decrease differed: temperature affected the fish biomass production mainly through a decrease in population standing stock biomass, and through shifts in size- and age-distributions toward a higher proportion of young and small individuals in warm lakes; brown water color, on the other hand, mainly influenced fish biomass production through negative effects on individual body growth and length-at-age. In addition to these findings, we observed that the effects of temperature and brown water color on individual-level processes varied over ontogeny. Body growth only responded positively to higher temperatures among young perch, and brown water color had a stronger negative effect on body growth of old than on young individuals. Thus, to better understand and predict future fish biomass production, it is necessary to integrate both individual- and population-level responses and to acknowledge within-species variation. Our results suggest that global climate change, leading to browner and warmer waters, may negatively affect fish biomass production, and this effect may be stronger than caused by increased temperature or water color alone.

  • 43. Vrede, Tobias
    et al.
    Drakare, Stina
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hein, Arne
    Liess, Antonia
    Olsson, Jens
    Persson, Jonas
    Quevedo, Mario
    Stabo, Henrik Ragnarsson
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Ecological stoichiometry of Eurasian perch - intraspecific variation due to size, habitat and diet2011In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 6, p. 886-896Article in journal (Refereed)
    Abstract [en]

    The turnover and distribution of energy and nutrients in food webs is influenced by consumer stoichiometry. Although the stoichiometry of heterotrophs is generally considered to vary only little, there may be intraspecific variation due to factors such as habitat, resources, ontogeny and size. We examined intraspecific variation in Eurasian perch Perca fluviatilis stoichiometry, a common species that exhibits habitat and resource specialization, ontogenetic niche shifts and a large size range. This study investigated the elemental stoichiometry of a wide size range of perch from littoral and pelagic habitats. The mean C:N:P stoichiometry of whole perch was 37:9:1 (molar ratios). However, %C, %P, C:N, C:P and N:P varied with size, morphology, habitat and diet category. These factors together explained 24-40% of the variation in C:N:P stoichiometry. In contrast, perch stoichiometry was not related to diet stoichiometry, suggesting that the former is homeostatically regulated. The results suggest that the high P content of perch may result in stoichiometric constraints on the growth of non-piscivorous perch, and that piscivory is an efficient strategy for acquiring P. Resource polymorphism, individual diet specialization and intraspecific size variation are widespread among animals. Thus changes in stoichiometry with size, habitat, morphology and resource use, and therefore also stoichiometric demands, are probably common.

  • 44.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Alexander, Eiler
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.; eDNA Solut Ltd, Molndal, Sweden..
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Effects of predation stress and food ration on perch gut microbiota2018In: Microbiome, ISSN 0026-2633, E-ISSN 2049-2618, Vol. 6, article id 28Article in journal (Refereed)
    Abstract [en]

    Background: Gut microbiota provide functions of importance to influence hosts' food digestion, metabolism, and protection against pathogens. Factors that affect the composition and functions of gut microbial communities are well studied in humans and other animals; however, we have limited knowledge of how natural food web factors such as stress from predators and food resource rations could affect hosts' gut microbiota and how it interacts with host sex. In this study, we designed a two-factorial experiment exposing perch (Perca fluviatilis) to a predator (pike, Esox lucius), and different food ratios, to examine the compositional and functional changes of perch gut microbiota based on 16S rRNA amplicon sequencing. We also investigated if those changes are host sex dependent.

    Results: We showed that overall gut microbiota composition among individual perch significantly responded to food ration and predator presence. We found that species richness decreased with predator presence, and we identified 23 taxa from a diverse set of phyla that were over-represented when a predator was present. For example, Fusobacteria increased both at the lowest food ration and at predation stress conditions, suggesting that Fusobacteria are favored by stressful situations for the host. In concordance, both food ration and predation stress seemed to influence the metabolic repertoire of the gut microbiota, such as biosynthesis of other secondary metabolites, metabolism of cofactors, and vitamins. In addition, the identified interaction between food ration and sex emphasizes sex-specific responses to diet quantity in gut microbiota.

    Conclusions: Collectively, our findings emphasize an alternative state in gut microbiota with responses to changes in natural food webs depending on host sex. The obtained knowledge from this study provided us with an important perspective on gut microbiota in a food web context.

  • 45.
    Zhang, Lai
    et al.
    Yangzhou Univ, Sch Math Sci, Yangzhou 225002, Jiangsu, Peoples R China;Umea Univ, Dept Math & Math Stat, SE-90187 Umea, Sweden.
    Thibert-Plante, Xavier
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden.
    Ripe, Jorgen
    Lund Univ, Dept Biol, Theoret Populat Ecol & Evolut Grp, S-22362 Lund, Sweden.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Brannstrom, Ake
    Umea Univ, Dept Math & Math Stat, SE-90187 Umea, Sweden;Int Inst Appl Syst Anal, Evolut & Ecol Program, A-2361 Laxenburg, Austria.
    Biodiversity loss through speciation collapse: Mechanisms, warning signals, and possible rescue2019In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, no 8, p. 1504-1516Article in journal (Refereed)
    Abstract [en]

    Speciation is the process that generates biodiversity, but recent empirical findings show that it can also fail, leading to the collapse of two incipient species into one. Here, we elucidate the mechanisms behind speciation collapse using a stochastic individual-based model with explicit genetics. We investigate the impact of two types of environmental disturbance: deteriorated visual conditions, which reduce foraging ability and impede mate choice, and environmental homogenization, which restructures ecological niches. We find that: (1) Species pairs can collapse into a variety of forms including new species pairs, monomorphic or polymorphic generalists, or single specialists. Notably, polymorphic generalist forms may be a transient stage to a monomorphic population; (2) Environmental restoration enables species pairs to reemerge from single generalist forms, but not from single specialist forms; (3) Speciation collapse is up to four orders of magnitude faster than speciation, while the reemergence of species pairs can be as slow as de novo speciation; (4) Although speciation collapse can be predicted from either demographic, phenotypic, or genetic signals, observations of phenotypic changes allow the most general and robust warning signal of speciation collapse. We conclude that factors altering ecological niches can reduce biodiversity by reshaping the ecosystem's evolutionary attractors.

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