umu.sePublications
Change search
Refine search result
1 - 17 of 17
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bartels, Pia
    et al.
    Department of Ecology and Genetics, Limnology, Uppsala University, Uppsala, Sweden.
    Hirsch, Philipp E.
    Svanbäck, Richard
    Eklöv, Peter
    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.

  • 2.
    Bartels, Pia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
    Hirsch, Philipp
    Svanbäck, Richard
    Eklöv, Peter
    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, no 6, 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.

  • 3. Bolnick, Daniel I
    et al.
    Svanbäck, Richard
    Araújo, Márcio S.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous2007In: Proceedings of the National Academy of Sciences, 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.

  • 4. Bolnick, Daniel
    et al.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Fordyce, James
    Yang, Louie
    Davis, Jeremy
    Hulsey, Darrin
    Forister, Matthew
    The ecology of individuals: incidence and implications of individual specialization2003In: American Naturalist, Vol. 161, p. 1-28Article in journal (Refereed)
  • 5. Eklöv, Peter
    et al.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Predation favors adaptive morphological variation in perch populationsManuscript (Other academic)
  • 6.
    Nonaka, Etsuko
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Biology, University of New Mexico, Albuquerque, NM, USA.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics/Limnology, Uppsala University.
    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, 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.

  • 7.
    Nonaka, Etsuko
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Metapopulation Research Centre, Department of Biosciences, University of Helsinki, Helsinki, Finland.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics/Limnology, Uppsala University.
    Thibert-Plante, Xavier
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 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.

  • 8.
    Persson, L
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Claessen, D
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    De Roos,, A M
    Byström, P
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sjögren, S
    Svanbäck, Richard
    Wahlström, E
    Westman, E
    Cannibalism in a size-structured population: energy extraction and control2004In: Ecological Monographs, Vol. 74, p. 135-157Article in journal (Refereed)
  • 9.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bolnick, DI
    Intraspecific competition affects the strength of individual specialization: an optimal diet theory method2005In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, no 7, p. 993-1012Article in journal (Refereed)
    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.

  • 10.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Eklöv, Peter
    Effects of habitat and food resources on morphology and ontogenetic growth trajectories in perch2002In: Oecologia, Vol. 131, p. 61-70Article in journal (Refereed)
  • 11.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Eklöv, Peter
    Genetic variation and phenotypic plasticity: Causes of morphological and dietary variation in Eurasian perch2006In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 8, no 1, p. 37-49Article in journal (Refereed)
  • 12.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Eklöv, Peter
    Morphology dependent foraging efficiency in perch: a trade-off for ecological specialization?2003In: Oikos, Vol. 102, p. 273-284Article in journal (Refereed)
  • 13.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Eklöv, Peter
    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.
  • 14.
    Svanbäck, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    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 zoo-plankton 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.

  • 15. Svanbäck, Richard
    et al.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Population Density Fluctuations Change the Selection Gradient in Eurasian Perch2009In: The American Naturalist, ISSN 0003-0147, 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.

  • 16. Svanbäck, Richard
    et al.
    Rydberg, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Leonardsson, Kjell
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Diet specialization in a fluctuating population of Saduria entomon: a consequence of resource or forager densities?2011In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 6, p. 848-854Article in journal (Refereed)
    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.

  • 17. Vrede, Tobias
    et al.
    Drakare, Stina
    Eklöv, Peter
    Hein, Arne
    Liess, Antonia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olsson, Jens
    Persson, Jonas
    Quevedo, Mario
    Ragnarsson Stabo, Henrik
    Svanbäck, Richard
    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.

1 - 17 of 17
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf