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Svanbäck, Richard
Publications (10 of 17) Show all publications
Bartels, P., Hirsch, P., Svanbäck, R. & Eklöv, P. (2016). Dissolved organic carbon reduces habitat coupling by top predators in lake ecosystems. Ecosystems (New York. Print), 19(6), 955-967
Open this publication in new window or tab >>Dissolved organic carbon reduces habitat coupling by top predators in lake ecosystems
2016 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, no 6, p. 955-967Article in journal (Refereed) Published
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.

Keywords
allochthony, brownification, food web coupling, visibility, foraging, climate change
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-129994 (URN)10.1007/s10021-016-9978-x (DOI)000386710000001 ()
Available from: 2017-01-11 Created: 2017-01-11 Last updated: 2018-06-09Bibliographically approved
Nonaka, E., Svanbäck, R., Thibert-Plante, X., Englund, G. & Brännström, Å. (2015). Mechanisms by which phenotypic plasticity affects adaptive divergence and ecological speciation. American Naturalist, 186(5), E126-E143
Open this publication in new window or tab >>Mechanisms by which phenotypic plasticity affects adaptive divergence and ecological speciation
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2015 (English)In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, no 5, p. E126-E143Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
University of Chicago Press, 2015
Keywords
assortative mating, eco-evolutionary dynamics, ecological, speciation, habitat choice, individual-based model, phenotypic plasticity
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-87677 (URN)10.1086/683231 (DOI)000363928900003 ()
Note

Originally published in thesis in manuscript form.

Available from: 2014-04-07 Created: 2014-04-07 Last updated: 2018-06-08Bibliographically approved
Nonaka, E., Brännström, Å. & Svanbäck, R. (2014). Assortative mating can limit the evolution of phenotypic plasticity. Evolutionary Ecology, 28(6), 1057-1074
Open this publication in new window or tab >>Assortative mating can limit the evolution of phenotypic plasticity
2014 (English)In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 28, no 6, p. 1057-1074Article in journal (Refereed) Published
Abstract [en]

Phenotypic plasticity, the ability to adjust phenotype to the exposed environment, isoften advantageous for organisms in heterogeneous environments. Although the degrees ofplasticity appear limited in nature, many studies have reported low costs of plasticity invarious species. Existing studies argue for ecological, genetic, or physiological costs orselection eliminating plasticity with high costs, but have not considered costs arising fromsexual selection. Here, we show that sexual selection caused by mate choice can impede theevolution of phenotypic plasticity in a trait used for mate choice. Plasticity can remain low tomoderate even in the absence of physiological or genetic costs, when individualsphenotypically adapted to contrasting environments through plasticity can mate with eachother 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 ofplasticity is constrained by sexual selection. This occurs at intermediate strengths of femalechoosiness we tested. Our results demonstrate that mate choice is a potential source of anindirect cost to phenotypic plasticity.

Place, publisher, year, edition, pages
Springer, 2014
Keywords
assortative mating, disruptive selection, magic trait, mate choice, phenotypic diversification, phenotypic plasticity, sexual selection, individual-based model
National Category
Ecology Evolutionary Biology Other Mathematics
Identifiers
urn:nbn:se:umu:diva-87674 (URN)10.1007/s10682-014-9728-5 (DOI)000344075200006 ()
Available from: 2014-04-07 Created: 2014-04-07 Last updated: 2018-06-08Bibliographically approved
Bartels, P., Hirsch, P. E., Svanbäck, R. & Eklöv, P. (2012). Water Transparency Drives Intra-Population Divergence in Eurasian Perch (Perca fluviatilis). PLoS ONE, 7(8), e43641
Open this publication in new window or tab >>Water Transparency Drives Intra-Population Divergence in Eurasian Perch (Perca fluviatilis)
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 8, p. e43641-Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
San Francisco: Public Library of Science, 2012
National Category
Environmental Sciences Ecology Zoology
Identifiers
urn:nbn:se:umu:diva-68304 (URN)10.1371/journal.pone.0043641 (DOI)000308063700123 ()
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2018-06-08Bibliographically approved
Svanbäck, R., Rydberg, C., Leonardsson, K. & Englund, G. (2011). Diet specialization in a fluctuating population of Saduria entomon: a consequence of resource or forager densities?. Oikos, 120(6), 848-854
Open this publication in new window or tab >>Diet specialization in a fluctuating population of Saduria entomon: a consequence of resource or forager densities?
2011 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 6, p. 848-854Article in journal (Refereed) Published
Abstract [en]

Intraspecific competition has been shown to favor diet specialization among individuals. However, the question whether the competition takes the form of interference or exploitative in driving diet specialization has never been investigated. We investigated individual diet specialization in the isopod Saduria entomon, in relation to forager and resource biomasses in a system that exhibits predator–prey fluctuations in density. We found that individual diet specialization was only affected by the biomass of their preferred prey (Monoporeia affinis) and not by Saduria biomass; diet specialization was higher when Monoporeia biomass was low compared to when there were high Monoporeia biomass. Population diet breadth increased at low Monoporeia biomass whereas individual diet breadths were marginally affected by Monoporeia biomass. Overall, this led to the increase in diet specialization at low Monoporeia biomass. This study shows that predator–prey dynamics might influence diet specialization in the predator and that resource biomass, not forager biomass might be important for individual diet specialization.

Keywords
disruptive selection; ecological specialization; individual specialization; sympatric speciation; natural-populations; functional-response; alternative prey; niche width; sea otters; competition
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-40975 (URN)10.1111/j.1600-0706.2010.18945.x (DOI)
Available from: 2011-03-15 Created: 2011-03-15 Last updated: 2018-06-08Bibliographically approved
Vrede, T., Drakare, S., Eklöv, P., Hein, A., Liess, A., Olsson, J., . . . Svanbäck, R. (2011). Ecological stoichiometry of Eurasian perch: intraspecific variation due to size, habitat and diet. Oikos, 120(6), 886-896
Open this publication in new window or tab >>Ecological stoichiometry of Eurasian perch: intraspecific variation due to size, habitat and diet
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2011 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 6, p. 886-896Article in journal (Refereed) Published
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.

National Category
Zoology Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-44168 (URN)10.1111/j.1600-0706.2010.18939.x (DOI)
Available from: 2011-05-24 Created: 2011-05-24 Last updated: 2018-06-08Bibliographically approved
Svanbäck, R. & Persson, L. (2009). Population Density Fluctuations Change the Selection Gradient in Eurasian Perch. The American Naturalist, 173(4), 507-516
Open this publication in new window or tab >>Population Density Fluctuations Change the Selection Gradient in Eurasian Perch
2009 (English)In: The American Naturalist, ISSN 0003-0147, Vol. 173, no 4, p. 507-516Article in journal (Refereed) Published
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.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-23258 (URN)10.1086/597223 (DOI)
Available from: 2009-06-08 Created: 2009-06-08 Last updated: 2018-06-08Bibliographically approved
Bolnick, D. I., Svanbäck, R., Araújo, M. S. & Persson, L. (2007). Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous. Proceedings of the National Academy of Sciences, 104(24), 10075-10079
Open this publication in new window or tab >>Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous
2007 (English)In: Proceedings of the National Academy of Sciences, Vol. 104, no 24, p. 10075-10079Article in journal (Refereed) Published
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.

National Category
Zoology Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-15425 (URN)10.1073/pnas.0703743104 (DOI)
Available from: 2007-07-12 Created: 2007-07-12 Last updated: 2018-06-09Bibliographically approved
Svanbäck, R. & Eklöv, P. (2006). Genetic variation and phenotypic plasticity: Causes of morphological and dietary variation in Eurasian perch. Evolutionary Ecology Research, 8(1), 37-49
Open this publication in new window or tab >>Genetic variation and phenotypic plasticity: Causes of morphological and dietary variation in Eurasian perch
2006 (English)In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 8, no 1, p. 37-49Article in journal (Refereed) Published
National Category
Zoology Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-3740 (URN)
Available from: 2004-02-11 Created: 2004-02-11 Last updated: 2018-06-09Bibliographically approved
Svanbäck, R. & Bolnick, D. (2005). Intraspecific competition affects the strength of individual specialization: an optimal diet theory method. Evolutionary Ecology Research, 7(7), 993-1012
Open this publication in new window or tab >>Intraspecific competition affects the strength of individual specialization: an optimal diet theory method
2005 (English)In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, no 7, p. 993-1012Article in journal (Refereed) Published
Abstract [en]

Question: Why would individuals that inhabit the same environment choose to feed on different subsets of the available resources?

Mathematical method: We outline a flexible model that combines phenotypic variation with optimal diet theory and population dynamics. We then apply this model to investigate the role of different types of trade-offs. phenotype diversity and level of competition in determining the degree of individual specialization.

Key assumptions: The foragers in the model are omniscient and maximize energy intake per time unit.

Conclusion: Numerical simulations match empirical observations that changes in population density can alter the degree of individual specialization. Forager density and phenotypic variation affected prey densities. which in turn affected forager diet breadth and fitness (energy income). We propose that this feedback can explain the empirical relationship between forager density and the degree of individual specialization in the forager population.

National Category
Ecology Environmental Sciences Zoology
Identifiers
urn:nbn:se:umu:diva-20673 (URN)10.1098/rspb.2006.0198 (DOI)
Available from: 2009-03-24 Created: 2009-03-24 Last updated: 2018-06-09
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