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  • 51.
    Scharnweber, Kristin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Chaguaceda, Fernando
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Fatty acid accumulation in feeding types of a natural freshwater fish population2020Inngår i: Artikkel i tidsskrift (Fagfellevurdert)
  • 52.
    Scharnweber, Kristin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Strandberg, Ursula
    Univ Eastern Finland, Dept Biol, Yliopistokatu 7,POB 111, Joensuu 80101, Finland; Ryerson Univ, Dept Biol & Chem, 350 Victoria St, Toronto, ON M5B 2K3, Canada.
    Marklund, Maria Helena Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ Adelaide, Inst Environm, Water Res Ctr, Dept Earth & Environm Sci, Adelaide, SA 5005, Australia.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Combining resource use assessment techniques reveals trade-offs in trophic specialization of polymorphic perch2016Inngår i: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 7, nr 8, artikkel-id e01387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trophic polymorphism has found to be common in many taxa and is a suggested mechanism of ecological speciation. To characterize the trophic linkages of specific morphotypes of organisms as well as a time-integrated niche use, several methods are available. In this study, we present data of multiple techniques to investigate the trophic divergence of Eurasian perch (Perca fluviatilis) that displays well-studied trophic polymorphism associated with littoral and pelagic habitats in lakes. We combined bulk stable isotope and fatty acid analyses on the muscle tissue of perch from three different lakes in Sweden with analyses of stomach content. By comparing the three methods, we aimed at providing a broad and highly resolved picture on the trophic divergence in freshwater fish. The degree in morphological divergence varied between perch caught in the three different lakes. Generally, perch caught in the pelagic zone were more streamlined compared to the ones caught in the littoral zone that had a deeper body, as shown by geometric morphometrics. The three diet assessment methods revealed different levels of information. Data on stomach content showed some preferences for specific dietary items in littoral and pelagic perch, but general trophic specialization could not be concluded due to the small sample size. Analyses of delta C-13 and delta N-15, however, confirmed these results as a long-term pattern connected to specific habitat use in two of the three lakes. Fatty acid signatures of perch reflected partly those of the prey items of the specific habitats. Although the proportions of the essential fatty acid 22:6n-3 were lower in littoral resources, the proportions in littoral fish were similar to the ones caught in the pelagic zone. We concluded that although a fundamental contribution from littoral resources exists in littoral phenotypes, a minor reliance on pelagic prey items is obviously needed to provide essential compounds. Thus, by combining the methods to characterize direct resource use (i.e., stomach analyses) with others that utilize trophic biomarkers (i.e., analyses of stable isotopes and fatty acids), we were able to illustrate the degree of variation in trophic divergence of perch but also shed some light on potential trade-offs that are related to resource specialization in freshwater fish.

  • 53. Sundblad, Göran
    et al.
    Bergström, Ulf
    Eklöv, Peter
    Spatial analysis shows recruitment habitat limitation of large predatory fishManuskript (preprint) (Annet vitenskapelig)
  • 54.
    Sundblad, Göran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bergström, Ulf
    Swedish University of Agricultural Sciences.
    Sandström, Alfred
    Institute of Freshwater Research.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Nursery habitat availability limits adult stock sizes of predatory coastal fish2014Inngår i: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 71, nr 3, s. 672-680Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Habitat protection is a strategy often proposed in fisheries management to help maintain viable populations of exploited species. Yet, quantifying the importance of habitat availability for population sizes is difficult, as the precise distribution of essential habitats is poorly known. To quantify the contribution from coastal nursery habitats to exploited fish population sizes, we related adult density to the amount of nursery habitat available for 12 populations of the two dominant predatory fish species in a 40 000-km2 archipelago area of the Baltic Sea. Habitat distribution was mapped using three conceptually different techniques, Maxent, generalized additive models, and random forest, using spawning and 0-group point samples. Adult densities were estimated from gillnet surveys. Regressions demonstrated no evident effect from fishing, whereas habitat availability had a positive effect, explaining almost half of the variation in population sizes of both species. This result shows that a substantial proportion of the potential production of adult fish can be estimated by mapping essential nursery habitats distribution. Responses were non-linear, indicating that habitat protection has largest effects where there is little available habitat. By demonstrating the importance of habitat limitation of two exploited fish species, we provide quantitative support to the benefits of habitat protection for fisheries.

  • 55.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eklov, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Catch me if you can: Predation affetcs divergence in a polyphenic species2011Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, nr 12, s. 3515-3526Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 56.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Effects of habitat and food resources on morphology and ontogenetic growth trajectories in perch.2002Inngår i: Oecologia 131: 61-70., Vol. 131, s. 61-70Artikkel i tidsskrift (Fagfellevurdert)
  • 57.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Genetic variation and phenotypic plasticity: causes of morphological variation in Eurasian perch2006Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 8, nr 1, s. 37-49Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 58.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Morphology dependent foraging efficiency in perch: a trade-off for ecological specialization?2003Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 102, nr 2, s. 273-284Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 59.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Morphology in perch affects habitat specific feeding efficiency2004Inngår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 18, nr 4, s. 503-510Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 60.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Fransson, Rebecca
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Holmgren, Kerstin
    Intra-specific competition drives multiple species trophic polymorphism in fish communities2008Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 117, nr 1, s. 114-124Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 61.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hirsch, Philipp E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bartels, Pia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Different venues, different menus: causes and consequences of disruptive selection in natural populations2011Manuskript (preprint) (Annet vitenskapelig)
  • 62.
    Svanbäck, Richard
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Quevedo, Mario
    Olsson, Jens
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Individuals in food webs: the relationships between trophic position, omnivory and among-individual diet variation2015Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 178, nr 1, s. 103-114Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 63. Vrede, Tobias
    et al.
    Drakare, Stina
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hein, Arne
    Liess, Antonia
    Olsson, Jens
    Persson, Jonas
    Quevedo, Mario
    Stabo, Henrik Ragnarsson
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Ecological stoichiometry of Eurasian perch - intraspecific variation due to size, habitat and diet2011Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, nr 6, s. 886-896Artikkel i tidsskrift (Fagfellevurdert)
    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.

12 51 - 63 of 63
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