uu.seUppsala universitets publikationer
Ändra sökning
Avgränsa sökresultatet
12 1 - 50 av 63
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Bartels, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Cucherousset, Julien
    Gudasz, Cristian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Jansson, Mats
    Karlsson, Jan
    Persson, Lennart
    Premke, Katrin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Rubach, Anja
    Steger, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars J.
    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.
    Terrestrial subsidies to lake food webs: An experimental approach2012Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 168, nr 3, s. 807-818Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cross-ecosystem movements of material and energy are ubiquitous. Aquatic ecosystems typically receive material that also includes organic matter from the surrounding catchment. Terrestrial-derived (allochthonous) organic matter can enter aquatic ecosystems in dissolved or particulate form. Several studies have highlighted the importance of dissolved organic carbon to aquatic consumers, but less is known about allochthonous particulate organic carbon (POC). Similarly, most studies showing the effects of allochthonous organic carbon (OC) on aquatic consumers have investigated pelagic habitats; the effects of allochthonous OC on benthic communities are less well studied. Allochthonous inputs might further decrease primary production through light reduction, thereby potentially affecting autotrophic resource availability to consumers. Here, an enclosure experiment was carried out to test the importance of POC input and light availability on the resource use in a benthic food web of a clear-water lake. Corn starch (a C-4 plant) was used as a POC source due to its insoluble nature and its distinct carbon stable isotope value (delta C-13). The starch carbon was closely dispersed over the bottom of the enclosures to study the fate of a POC source exclusively available to sediment biota. The addition of starch carbon resulted in a clear shift in the isotopic signature of surface-dwelling herbivorous and predatory invertebrates. Although the starch carbon was added solely to the sediment surface, the carbon originating from the starch reached zooplankton. We suggest that allochthonous POC can subsidize benthic food webs directly and can be further transferred to pelagic systems, thereby highlighting the importance of benthic pathways for pelagic habitats.

  • 2.
    Bartels, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Cucherousset, Julien
    Steger, Kristin
    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.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hillebrand, Helmut
    Reciprocal subsidies between freshwater and terrestrial ecosystems structure consumer-resource dynamics2012Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 93, nr 5, s. 1173-1182Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cross-ecosystem movements of material and energy, particularly reciprocal resource fluxes across the freshwater-land interface, have received major attention. Freshwater ecosystems may receive higher amounts of subsidies (i.e., resources produced outside the focal ecosystem) than terrestrial ecosystems, potentially leading to increased secondary production in freshwaters. Here we used a meta-analytic approach to quantify the magnitude and direction of subsidy inputs across the freshwater-land interface and to determine subsequent responses in recipient animals. Terrestrial and freshwater ecosystems differed in the magnitude of subsidies they received, with aquatic ecosystems generally receiving higher subsidies than terrestrial ecosystems. Surprisingly, and despite the large discrepancy in magnitude, the contribution of these subsidies to animal carbon inferred from stable isotope composition did not differ between freshwater and terrestrial ecosystems, likely due to the differences in subsidy quality. The contribution of allochthonous subsidies was highest to primary consumers and predators, suggesting that bottom-up and top-down effects may be affected considerably by the input of allochthonous resources. Future work on subsidies will profit from a food web dynamic approach including indirect trophic interactions and propagating effects.

  • 3.
    Bartels, Pia
    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.
    Svanbäck, Richard
    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.
    Intra-population niche separation mediated by water transparency limits habitat couplingManuskript (preprint) (Övrigt vetenskapligt)
  • 4.
    Bartels, Pia
    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.
    Svanbäck, Richard
    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.
    Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)2012Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 8, s. e43641-Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    Bartels, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hirsch, Philipp Emanuel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Dissolved Organic Carbon Reduces Habitat Coupling by Top Predators in Lake Ecosystems2016Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 19, s. 955-967Artikel i tidskrift (Refereegranskat)
    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.

  • 6.
    Chaguaceda, Fernando
    et al.
    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.
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Regulation of fatty acid composition related to ontogenetic changes and niche differentiation of a common aquatic consumer2020Ingår i: Artikel i tidskrift (Refereegranskat)
  • 7.
    Chaguaceda, Fernando
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Garrison, Julie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Nydahl, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Attermeyer, Katrin
    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.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Disentangling the effects of carbon fluxes and shading inherent to terrestrial DOC on lake food websManuskript (preprint) (Övrigt vetenskapligt)
  • 8.
    Chaguaceda, Fernando
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars
    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.
    Short-term apparent mutualism drives responses of aquatic prey at increasing productivity2020Ingår i: Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    According to apparent competition theory, sharing a predator should cause indirect interactions among prey that can substantially influence food-web responses to environmental drivers. However, empirical evidence of apparent competition under ongoing environmental change is still scarce. In an 8-week mesocosm experiment, we found that short-term responses of aquatic food webs to increasing productivity were strongly regulated by apparent mutualism between benthic and pelagic prey in the presence of a generalist fish. Following trends in natural systems, increasing productivity in our mesocosms favored the relative abundance of benthic prey. This elicited a shift in fish selectivity from pelagic to benthic prey driven by fish switching behavior which resulted in lower and delayed top-down control on pelagic prey. Our results highlight that apparent competition theory may explain food-web responses across environmental gradients, whereby resulting prey dynamics and stability may highly depend on the foraging behavior exhibited by generalist predators.

  • 9.
    Diehl, Sebastian
    et al.
    Umeå University, Department of Animal Ecology.
    Eklöv, Peter
    Umeå University, Department of Animal Ecology.
    EFFECTS OF PISCIVORE-MEDIATED HABITAT USE ON RESOURCES, DIET, AND GROWTH OF PERCH1995Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 76, nr 6, s. 1712-1726Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigated experimentally how presence or absence of different piscivores influenced habitat use, diet, and individual growth of two size classes of juvenile perch (Perca fluviatilis) and abundances of juvenile perch resources in different habitats. Pond enclosures encompassed 3 X 6 m of dense vegetation and 9 X 6 m of open habitat, and were stocked with 75 young-of-year and 30 1-yr-old perch and with either three piscivorous perch, three northern pike (Esox lucius), or no piscivores. Northern pike were both larger and possessed a larger gape than piscivorous perch. To isolate behavioral responses of juvenile perch to piscivores, we replaced consumed young-of-year perch. Prey fish mortality was lowest without piscivores and highest with northern pike. Young-of-year perch increased their use of vegetation in the presence of both piscivores, whereas 1-yr-old perch increased their use of vegetation only with northern pike. For both age classes of prey fish, increased use of the vegetation led to reduced individual growth, owing to two complementary mechanisms. First, the physical complexity of submerged macrophytes likely interfered with the benthic feeding of perch, Second, increased use of the (relatively small) vegetated habitat increased the mean density experienced by prey fish. Piscivore-induced changes of prey fish densities in the two habitats had substantial effects on the biomass of prey fish resources in the open habitat, but only minor effects in the vegetation. Sialis lutaria, the major predatory macroinvertebrate (approximate to 50% of total macroinvertebrate biomass in the open habitat), and total predatory macroinvertebrates were positively affected by piscivores in the open habitat, but not in the vegetation. Chironomids (<3% of total macroinvertebrate biomass in the vegetation) and the sizes of nonpredatory macroinvertebrates were negatively affected by piscivores in the vegetation, but not in the open habitat. Biomass of nonpredatory macroinvertebrates, Cladocera, and Copepoda did not differ among treatments in either habitat. From our review of field experiments, vulnerable prey fish always change their habitat use in the presence of piscivores. Behaviorally mediated indirect effects of piscivores on individual growth rates and prey fish resources were just as frequently observed as direct effects of piscivores on prey fish survival.

  • 10.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Chemical cues from multiple predator-prey interactions induce changes in behavior and growth of anuran larvae2000Ingår i: Oecologia, Vol. 123, nr 2, s. 192-199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chemical signals are used as information by prey to assess predation risk in their environment.

  • 11.
    Eklöv, Peter
    Umeå University, Department of Animal Ecology.
    Group Foraging Versus Solitary Foraging Efficiency In Piscivorous Predators - The Perch, Perca-Fluviatilis, And Pike, Esox-Lucius, Patterns1992Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 44, nr 2, s. 313-326Artikel i tidskrift (Refereegranskat)
  • 12.
    Eklöv, Peter
    et al.
    Umeå University, Department of Animal Ecology.
    Diehl, Sebastian
    Umeå University, Department of Animal Ecology.
    PISCIVORE EFFICIENCY AND REFUGING PREY - THE IMPORTANCE OF PREDATOR SEARCH MODE1994Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 98, nr 3-4, s. 344-353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In predator-prey interactions, the efficiency of the predator is dependent on characteristics of both the predator and the prey, as well as the structure of the environment. In a field enclosure experiment, we tested the effects of a prey refuge on predator search mode, predator efficiency and prey behaviour. Replicated enclosures containing young of the year (0+) and 1-year-old (1+) perch were stocked with 3 differentially sized individuals of either of 2 piscivorous species, perch (Perca fluviatilis), pike (Esox lucius), or no piscivorous predators. Each enclosure contained an open predator area with three small vegetation patches, and a vegetated absolute refuge for the prey. We quantified the behaviour of the predators and the prey simultaneously, and at the end of the experiment the growth of the predators and the mortality and habitat use of the prey were estimated. The activity mode of both predator species was stationary. Perch stayed in pairs in the vegetation patches whereas pike remained solitary and occupied the corners of the enclosure. The largest pike individuals stayed closest to the prey refuge whereas the smallest individuals stayed farthest away from the prey refuge, indicating size-dependent interference among pike. Both size classes of prey showed stronger behavioural responses to pike than to perch with respect to refuge use, distance from refuge and distance to the nearest predator. Prey mortality was higher in the presence of pike than in the presence of perch. Predators decreased in body mass in all treatments, and perch showed a relatively stronger decrease in body mass than pike during the experiment. Growth differences of perch and pike, and mortality differences of prey caused by predation, can be explained by predator morphology, predator attack efficiency and social versus interference behaviour of the predators. These considerations suggest that pike are more efficient piscivores around prey refuges such as the littoral zones of lakes, whereas perch have previously been observed to be more efficient in open areas, such as in the pelagic zones of lakes.

  • 13.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Halvarsson, Charlotta
    The trade-off between foraging activity and predation risk for Rana temporaria in different food environments2000Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 78, nr 5, s. 734-739Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     

    We evaluated the trade-off between foraging activity and predation risk for larvae of an anuran species presented with different types of food resources. In the laboratory we examined the effects of benthic and phytoplankton resources and the two types combined on the activity and mortality of larvae of the common frog, Rana temporaria, exposed to predatory larva, Dytiscus marginalis.

    Predation mortality of tadpoles increased with the duration of the experiment and was highest in the presence of the phytoplankton resource alone. This was explained by a decrease in prey activity in the benthic- and combined-resource treatments when the predator was present, whereas in the phytoplankton treatment, the activity of the tadpoles were similar in the presence or absence of the predator.

    In the presence of the predator, prey mainly used the bottom of the aquarium in the benthic- and combined-resource treatments. In contrast, in the phytoplankton treatment they used the water column more than in the other treatments. In the presence of the predator, the prey had a lower consumption rate in the phytoplankton treatment than in the other treatments.

    Predator activity did not change among treatments. The results suggest that the trade-off between foraging activity and predation mortality for anuran larvae is strongly affected by the types of food resources present in the environment.

     

     

  • 14.
    Eklöv, Peter
    et al.
    Lund University, Department of limnology.
    Hamrin, Stellan F
    Lund University, Department of limnology.
    PREDATORY EFFICIENCY AND PREY SELECTION - INTERACTIONS BETWEEN PIKE ESOX-LUCIUS, LUCIUS, PERCH PERCA-FLUVIATILIS AND RUDD SCARDINUS-ERYTHROPHTHALMUS1989Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 56, nr 2, s. 149-156Artikel i tidskrift (Refereegranskat)
  • 15.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Jonsson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Pike predators induce morphological changes in young perch and roach2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 70, nr 1, s. 155-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The morphological response of two 1 year-old prey species, perch Perca fluviatilis and roach Rutilus rutilus to the presence of predatory pike Esox lucius, was tested in a 6 week aquarium experiment. The growth of perch was higher than that of roach but there was no difference in growth of prey between predator and control treatments. The presence of pike caused morphological changes in both perch and roach. Perch showed an increase in body depth during the experiment whereas the morphological response of roach to pike was more related to a displacement of the dorsal and pelvic fins and width of the anal fin. Differences in morphological responses of perch and roach to pike can be interpreted by their overall differences in antipredator strategies.

  • 16.
    Eklöv, Peter
    et al.
    Umeå University, Department of Animal Ecology.
    Persson, Lennart
    Umeå University, Department of Animal Ecology.
    SPECIES-SPECIFIC ANTIPREDATOR CAPACITIES AND PREY REFUGES - INTERACTIONS BETWEEN PISCIVOROUS PERCH (PERCA-FLUVIATILIS) AND JUVENILE PERCH AND ROACH (RUTILUS-RUTILUS)1995Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 37, nr 3, s. 169-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The outcome of predator-prey interactions depends on the characteristics of predators and prey as well as the structure of the environment. In a replicated field enclosure experiment, we tested the effects of quantity and quality of different prey refuges (no structure, structure forming a partial refuge, and structure forming a complete refuge) on the interaction between piscivorous perch (Perca fluviatilis) and juvenile perch and roach (Rutilus rutilus). We quantified the behaviour of the predators and the prey and predator-induced prey mortality. The piscivores stayed in or close to the prey refuge and were more dispersed in the presence than in the absence of prey refuges. Survival of juvenile perch and roach decreased in the presence of predators and was higher for juvenile roach than for juvenile perch. In addition, juvenile perch survival increased with refuge efficiency. Roach formed schools which were denser in the presence of predators, had a higher swimming speed (both in the open water and in the refuge) and used a larger area than juvenile perch. Both prey species decreased their distance to the prey refuge and increased the proportion of their time spent in the refuge in the presence of predators. The number of switches between the open-water habitat and the prey refuge was higher for juvenile roach than for juvenile perch. Juvenile perch used different parts of the prey refuge in a flexible way depending both on presence of predators and refuge type whereas juvenile roach used the different parts of the prey refuge in fixed proportions over all refuge treatments. Our results suggest that juvenile roach had a overall higher capacity to avoid predation than juvenile perch. However, in the presence of qualitatively different prey refuges juvenile perch responded to predators with more flexible refuge use than juvenile roach. The differences in antipredator capacities of juvenile perch and roach when subjected to piscivorous perch predation may depend on differences in life history patterns of the two species.

  • 17.
    Eklöv, Peter
    et al.
    Umeå University, Department of Animal Ecology.
    Persson, Lennart
    Umeå University, Department of Animal Ecology.
    The response of prey to the risk of predation: Proximate cues for refuging juvenile fish1996Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 51, s. 105-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When prey encounter predators, they use different cues to indicate how to respond to minimize the predation risk. How such proximate cues in the environment correspond to the ultimate behaviour of the prey are important for understanding the outcome of predator-prey interactions. The precision of the anti-predator response of juvenile perch, Perca fluviatilis, and roach, Rutilus rutilus, when subjected to predation by piscivorous perch and pike, Esox lucius, and to different types of structure was tested in a wading pool experiment. The predation risk was varied between two habitats (one open water and one structured) by confining the predators to one of the two habitats. The prey were free to choose between habitats. Both perch and pike attacked both prey species but they were only successful in capturing roach. Roach swam faster than juvenile perch in the presence of perch, whereas juvenile perch swam faster than roach in the presence of pike. Juvenile perch inspected the predators more and showed a more flexible inspection behaviour than did roach. Juvenile perch decreased the number of switches between habitats and stayed in the predator-free part of the pool in the presence of perch. In contrast, roach increased their habitat switch frequency in the presence of perch and stayed in the vegetation structure even when there were perch there. Both prey species preferred to stay in the vegetation structure when pike were there. Juvenile perch used both the vegetation and pipe structure as refuges whereas roach used only the vegetation structure as a refuge. The results suggest that juvenile perch use a different cue when assessing predation risk and display a more flexible behaviour compared with roach which simply move into vegetation under the threat of predation irrespective of predator location. (C) 1996 The Association for the Study of Animal Behaviour

  • 18.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Ragnarsson, Hendrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Varför så få arter i svensk fiskfauna2003Ingår i: Miljöforskning, Vol. 5-6, s. 14-16Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 19.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Predation risk influences adaptive morphological variation in fish populations2006Ingår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 167, nr 3, s. 440-452Artikel i tidskrift (Refereegranskat)
    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.

  • 20.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    VanKooten, Tobias
    Facilitation among piscivorous predators: effects of prey habitat use2001Ingår i: Ecology, ISSN 0012-9658, Vol. 82, nr 9, s. 2486-2494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The combined effects of predators on prey may substantially differ from thatof each predator species alone because of alterations in prey behavior. Using enclosures within a pond, we examined experimentally the effects of two piscivorous predators on prey mortality and prey resource levels in two habitats. The two predators use two different foraging modes, which also allowed us to examine the behaviorally induced indirect effects of prey on predator growth and prey food resources. Both perch (Perca fluviatilis) and pike (Esox lucius) caused significant mortality of roach (Rutilus rutilus), and the combined predator mortality was higher than predicted from a multiplicative prey consumption model. Growth rates of perch were similar when enclosures contained only perch and when they contained perch combined with pike. The growth rate of pike was higher when they were together with perch compared to when alone. Growth of roach was similar among treatments. The invertebrate food resources of roach increased by a factor 10 in the open water but remained at similar levels throughout the experiment in the vegetation. Biomass of Daphnia longispina, the dominant zooplankton species in the open water, was strongly correlated with mortality of roach, indicating a density-mediated indirect effect of predators on prey resources. There was no indirect effect on D. longispina in the vegetation caused by habitat restriction of roach and only a weak relationship in the open water. There was a strong indirect effect of pike predation on macroinvertebrates induced by a habitat shift of roach. Our results suggest that there was facilitation between predators caused by conflicting antipredator behavior of roach, which resulted in density-mediated indirect effects on prey resources. The behavioral response of roach to the two predators also induced indirect effects on invertebrate prey.

     

     

  • 21.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Werner, Earl
    Multiple predator effects on size-dependent behavior and mortality of twospecies of anuran larvae2000Ingår i: OIKOS, Vol. 88, nr 2, s. 250-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study examined the effects of multiple predators on size-specific behavior and mortality of two species of anuran larvae. Particularly. we focused on how trail changes in predators and prey may be transmitted to other species in the food web. In labo

  • 22.
    Faulks, Leanne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Genetic and morphological divergence along the littoral–pelagic axis in two common and sympatric fishes: perch, Perca fluviatilis (Percidae) and roach, Rutilus rutilus (Cyprinidae)2015Ingår i: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 114, nr 4, s. 929-940Artikel i tidskrift (Refereegranskat)
    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.

  • 23.
    Faulks, Leanne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Ragnarsson-Stabo, Henrik
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Intraspecific Niche Variation Drives Abundance-Occupancy Relationships in Freshwater Fish Communities2015Ingår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, nr 2, s. 272-283Artikel i tidskrift (Refereegranskat)
    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.

  • 24.
    Hirsch, Philipp E
    et al.
    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.
    Reyes, Martha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Quevedo, Mario
    Cantabrian Institute of Biodiversity (ICAB), Oviedo University, Departmento Biología Organismos y Sistemas, Campus del Cristo, 33006 Oviedo, Spain.
    Fransson, Rebecca
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Replicated divergence in two consumer species affected by resource availabilityManuskript (preprint) (Övrigt vetenskapligt)
  • 25.
    Hirsch, Philipp E
    et al.
    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.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Indirect trophic interactions with an invasive species affect phenotypic divergence in a top consumer2013Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 172, nr 1, s. 245-256Artikel i tidskrift (Refereegranskat)
    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.

  • 26.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Hoffman, Eric A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Olsson, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Group stability and homing behavior but no kin group sturcture in a coral reef fish2005Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 16, nr 3, s. 521-527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the reasons behind stable group formations has received considerable theoretical and empirical attention. Stable groups displaying homing behavior have been suggested to form as a result of, for instance, benefits from knowledge of the social or physical environment or through kin selection and the forming of kin groups. However, no one has disentangled preference for grouping in a familiar location from preference for grouping with familiar or related individuals. To investigate this, we conducted a series of field experiments and a group genetic analysis on the group-living Banggai cardinalfish (Pterapogon kauderni). We found homing behavior but no evidence for recognition of familiar group members. Instead, homing was based on the original location of their group rather than the individuals in that group. Moreover, we found no evidence for kin structures within these groups. We suggest that benefits from living in a known social environment drive homing behavior in this species and that homing behavior is not enough for the formation of kin group structures. Instead, our results suggest that kin recognition may be a prerequisite for the forming of kin groups.

  • 27.
    Liess, Antonia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Olsson, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Quevedo, Mario
    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.
    Vrede, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Hillebrand, Helmut
    Food web complexity affects stoichiometric and trophic interactions2006Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 114, nr 1, s. 117-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stoichiometry of trophic interactions has mainly been studied in simple consumer–prey systems, whereas natural systems often harbour complex food webs with abundant indirect effects. We manipulated the complexity of trophic interactions by using simple laboratory food webs and complex field food webs in enclosures in Lake Erken. In the simple food web, one producer assemblage (periphyton) and its consumers (benthic snails) were amended by perch, which was externally fed by fish food. In the complex food web, two producer assemblages (periphyton and phytoplankton), their consumers (benthic invertebrates and zooplankton) and perch feeding on zooplankton were included. In the simple food web perch affected the stoichiometry of periphyton and increased periphyton biomass and the concentration of dissolved inorganic nitrogen. Grazers reduced periphyton biomass but increased its nutrient content. In the complex food web, in contrast to the simple food web, perch affected periphyton biomass negatively but increased phytoplankton abundance. Perch had no influence on benthic invertebrate density, zooplankton biomass or periphyton stoichiometry. Benthic grazers reduced periphyton biomass and nutrient content. The difference between the simple and the complex food web was presumably due to the increase of pelagic cyanobacteria (Gloeotrichia sp.) with fish presence in the complex food web, thus fish had indirect negative effects on periphyton biomass through nutrient competition and shading by cyanobacteria. We conclude that the higher food web complexity through the presence of pelagic primary producers (in this case Gloeotrichia sp.) influences the direction and strength of trophic and stoichiometric interactions.

  • 28.
    Marklund, Maria H. K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Habitat coupling mediates trophic cascades in an aquatic community2019Ingår i: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, nr 9Artikel i tidskrift (Refereegranskat)
    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.

  • 29.
    Marklund, Maria H. K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Faulks, Leanne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi. 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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Zha, Yinghua
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, NKS BioClinicum, Solna, Sweden.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Asymmetrical habitat coupling of an aquatic predator: The importance of individual specialization2019Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 9, nr 6, s. 3405-3415Artikel i tidskrift (Refereegranskat)
    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.

  • 30.
    Marklund, Maria H. K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Water Research Centre and The Environment Institute, School of Biological Sciences, Univ. of Adelaide, North Terrace, SA, Australia.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Zha, Yinghua
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Scharnweber, Kristin
    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.
    The influence of habitat accessibility on the dietary and morphological specialisation of an aquatic predator2018Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 127, nr 1, s. 160-169Artikel i tidskrift (Refereegranskat)
    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.

  • 31.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Blenckner, Thorsten
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Pettersson, Kurt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Physical and chemical properties determine zebra mussel invasion success in lakes2011Ingår i: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 669, nr 1, s. 227-236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To address the question whether the abundance of an invasive species can be explained by physical and chemical properties of the invaded ecosystems, we gathered density data of invasive zebra mussels and the physical and chemical data of ecosystems they invaded. We assembled published data from 55 European and 13 North American lakes and developed a model for zebra mussel density using a generalized additive model (GAM) approach. Our model revealed that the joint effect of surface area, total phosphorus and calcium concentrations explained 62% of the variation in Dreissena density. Our study indicates that large and less productive North American lakes can support larger local populations of zebra mussels. Our results suggest that the proliferation of an exotic species in an area can partially be explained by physical and chemical properties of the recipient environment.

  • 32.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Blenckner, Thorsten
    Eklöv, Peter
    Pettersson, Kurt
    Why is an invasive species more successful in some areas than others? A comparison of zebra mussel density in North American and European lakesIngår i: Artikel i tidskrift (Refereegranskat)
  • 33.
    Naddafi, Rahmat
    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.
    Pettersson, Kurt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Non-lethal predator effects on the feeding rate and prey selection of the exotic zebra mussel (Dreissena polymorpha)2007Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 116, nr 8, s. 1289-1298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Predators may induce changes in prey feeding that indirectly influence both the impact of prey on resource abundances and their interactions with other species in their community. We evaluated whether clearance and excretion (faeces plus pseudofaeces) of phytoplankton by zebra mussels were affected by the presence of predatory cues from roach (Rutilus rutilus) and signal crayfish (Pasifastacus leniusculus). We found that non-lethal effects of predators can alter zebra mussel clearance rate and thus the impact of zebra mussels on phytoplankton. Risk cues released by both predators had similar negative effects on clearance rate of zebra mussels and cascading positive indirect effects on phytoplankton resources. Predation risk had a stronger effect on zebra mussels' clearance rate of cyanobacteria and diatoms than cryptophytes and chrysophytes. The presence of predators did not significantly affect the rate at which zebra mussels expelled and excreted phytoplankton, although there was a tendency for more chlorophyll to be expelled and excreted in the presence of predators. Our results contribute to the growing evidence that predators indirectly affect resource dynamics and food web structure through their non-lethal effects on consumers. Our results suggest that exotic species such as zebra mussels can show behavioural responses to both native (e.g., roach) and exotic (e.g., crayfish) predators.

  • 34.
    Naddafi, Rahmat
    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.
    Pettersson, Kurt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Stoichiometric constraints do not limit successful invaders: zebra mussels in Swedish lakes2009Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 4, nr 4, s. e5345-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Elemental imbalances of carbon (C): nitrogen (N): phosphorus (P) ratios in food resources can constrain the growth of grazers owning to tight coupling between growth rate, RNA allocation and biomass P content in animals. Testing for stoichiometric constraints among invasive species is a novel challenge in invasion ecology to unravel how a successful invader tackles ecological barriers in novel ecosystems.Methodology/Principal Findings: We examined the C:P and N:P ratios and the condition factor of a successful invader in lakes, the zebra mussel (Dreissena polymorpha), collected from two Swedish lakes. Concurrently, we analyzed the elemental composition of the food (seston) and tissue of the mussels in which nutrient composition of food and mussels varied over time. Zebra mussel condition factor was weakly related to the their own tissue N:P and C:P ratios, although the relation with the later ratio was not significant. Smaller mussels had relatively lower tissue N:P ratio and higher condition factor. There was no difference in C:P and N:P ratios between seston and mussels' tissues. Our results indicated that the variation in nutrient stoichiometry of zebra mussels can be explained by food quality and quantity. Conclusions/Significance: Our study suggests that fitness of invasive zebra mussels is not constrained by nutrient stoichiometry which is likely to be important for their proliferation in novel ecosystems. The lack of imbalance in C:P and N:P ratios between seston and mussels along with high tissue C:P ratio of the mussel allow them to tolerate potential P limitation and maintain high growth rate. Moreover, zebra mussels are able to change their tissue C:P and N:P ratios in response to the variation in elemental composition of their food. This can also help them to bypass potential nutrient stoichiometric constraints. Our finding is an important step towards understanding the mechanisms contributing to the success of exotic species from stoichiometric principles.

  • 35. Naddafi, Rahmat
    et al.
    Goedkoop, Willem
    Grandin, Ulf
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Variation in tissue stoichiometry and condition index of zebra mussels in invaded Swedish lakes2012Ingår i: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 14, nr 10, s. 2117-2131Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We examined the spatial variation in carbon:nitrogen:phosphorus (C:N:P) stoichiometry and condition index of the zebra mussel (Dreissena polymorpha), non-indigenous species, in four Swedish lakes with different productivity. Within-lake variability was observed in tissue C:N molar ratios of Dreissena in all lakes and in tissue C:P ratio only in three lakes. Depth had no effect on tissue C:P and N:P ratios of Dreissena. A positive correlation was found between C:N:P stoichiometry of seston and elemental composition of zebra mussel in one of the lakes. Tissue C:N and N:P ratios were the main factors that related to zebra mussel condition index. Zebra mussel condition was positively related to tissue C:N ratio. Smaller Dreissena had higher C:N ratio than larger Dreissena in two of the four lakes. Zebra mussels in the lake with highest productivity had lower C:P and N:P ratios than zebra mussels in the lake with lowest productivity. Our study suggests that the zebra mussel may modify their phosphorus content in relation to lake trophic state, and therefore cope with stoichiometric constraints which may explain the invasion success of this and other related species.

  • 36.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Pettersson, Kurt
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Effect of zebra mussel , an exotic freshwater species, on seston stoichiometry2008Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Artikel i tidskrift (Refereegranskat)
  • 37.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Pettersson, Kurt
    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 the zebra mussel, an exotic freshwater species, on seston stoichiometry2008Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 53, nr 5, s. 1973-1987Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We examined the effect of the zebra mussel, Dreissena polymorpha, an exotic species, on seston stoichiometry by conducting laboratory experiments in which we varied nutrient composition of seston and mussels over time. Zebra mussels altered the stoichiometry of seston through removal of particulate organic nutrients and changed the stoichiometry of the dissolved nutrient pool through nutrient excretion. Grazers had stronger effects on carbon : phosphorus (C : P) and nitrogen (N) : P ratios than on the C:N ratio of seston. Elemental residence time in tissue and high mass-specific nutrient excretion by small mussels caused small mussels to be more efficient nutrient recyclers than larger mussels. Zebra mussels reduced P availability through enhancing C: P and N: P molar ratios of seston during the period extending from June to August, when P was limited in the lake, and increased the C:N molar ratio of seston in June, when N was at the minimum level in the lake. C: P and N: P molar ratios for zebra mussel tissue were higher in August and somewhat in September than in all other months. N was retained more efficiently than P in Dreissena tissue. Nutrient mass-specific uptake rate was higher than excretion rate by zebra mussels.

  • 38.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Pettersson, Kurt
    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.
    Predation and physical environment structure the density and population size structure of zebra mussels2010Ingår i: Journal of The North American Benthological Society, ISSN 0887-3593, E-ISSN 1937-237X, Vol. 29, nr 2, s. 444-453Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The zebra mussel (Dreissena polymorpha) provides one example of successful invaders in novel environments. However, little attention has been devoted to exploring the factors regulating zebra mussel density and population size structure at the local scale. We tested effects of physicochemical factors and fish predation on the density of zebra mussels at several sites and between years in a natural lake. Water depth and roach (Rutilus rutilus) density were the most important variables affecting local zebra mussel density. Substrate was also an important factor but affected Dreissena density only at the shallowest depth examined (2 m), which also supported a large population of the mussels. Mean shell length of Dreissena increased with water depth. Our results indicate that predation pressure, intraspecific competition, and food limitation might be responsible for variation in zebra mussel density and population size structure in space and time and that fish predation might have strong top-down effects on zebra mussel populations.

  • 39.
    Naddafi, Rahmat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Pettersson, Kurt
    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.
    The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition2007Ingår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, nr 5, s. 823-842Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate the impact of zebra mussels (Dreissena polymorpha) on phytoplankton community composition, temporal variability in selective feeding by the mussels was determined from April to November 2005 in a natural lake using Delayed Fluorescence (DF) excitation spectroscopy. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics; mussels showed a consistent preference for cryptophytes and avoidance of chlorophytes and cyanobacteria. Diatoms, chrysophytes and dinoflagellates responded differentially to zebra mussel grazing depending on their size. Analysis of excreted products of the zebra mussels revealed that in addition to chlorophytes and cyanobacteria, phytoplankton >50 μm and very small phytoplankton (≤7 μm) were largely expelled in pseudofaeces. The zebra mussel is a selective filter-feeder that alters its feeding behaviour in relation to phytoplankton composition to capture and ingest high quality phytoplankton, especially when phytoplankton occur in preferred size ranges. Flexibility of zebra mussel feeding behaviour and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences.

  • 40. Nilsson, A.P.
    et al.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Finding food and staying alive2018Ingår i: Biology and ecology of pike / [ed] Christian Skov; P. Anders Nilsson, Boca Raton, FL: CRC Press, 2018, s. 9-31Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This book sets out to bridge the order scales among pike researchers, populations, communities, management, and fisheries. It emphasizes the progress of pike research during the last two decades, during which the order-bridging approach emerged. This framework underpins the text and the message, to convey its importance to pike research and to fish research in general. In addition, a considerable part of the book is devoted to management implications and highlights aspects of human dimensions in recreational fisheries.

  • 41.
    Olsson, J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Eklöv, P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Effects of habitat specific structure and feeding mode on phenotypic plasticity in Eurasian perch, Perca fluviatilis.2005Ingår i: Evolutionary Ecology Research, Vol. 7, s. 1109-1123.Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 42.
    Olsson, Jens
    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.
    Habitat structure, feeding mode and morphological reversibility: factors influencing phenotypic plasticity in perch2005Ingår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, nr 8, s. 1109-1123Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Questions: Do both habitat structure and feeding mode contribute to morphological divergence within fish populations? To what extent may an induced morphology be reversed?

    Organism: Young-of-the-year Eurasian perch (Perca fluviatilis L.).

    Methods: An aquarium experiment with a 2 × 2 factorial design (two levels of habitat structure and two levels of feeding mode). The habitat structure and feeding mode were reversed for perch in two habitat treatments midway through the experiment.

    Results: Both habitat structure and feeding mode contributed to morphological divergence (40.7% and 4.9% of the total variation respectively), which suggests that both habitat complexity and prey type diversity influence morphological adaptations in this fish species. Perch morphology is highly plastic and can be reversed in as short a time as 4 weeks.

     

  • 43.
    Olsson, Jens
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Svanbäck, Richard
    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 resource level and habitat type on behavioural and morphological plasticity in Eurasian perch2007Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 152, nr 1, s. 48-56Artikel i tidskrift (Refereegranskat)
    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.

  • 44.
    Olsson, Jens
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Svanbäck, Richard
    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.
    Growth rate constrain morphological divergence when driven by competition2006Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 115, nr 1, s. 15-22Artikel i tidskrift (Refereegranskat)
    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.

  • 45.
    Persson, L
    et al.
    Umeå University, Department of Animal Ecology.
    Andersson, J
    Umeå University, Department of Animal Ecology.
    Wahlstrom, E
    Umeå University, Department of Animal Ecology.
    Eklöv, Peter
    Umeå University, Department of Animal Ecology.
    Size-specific interactions in lake systems: Predator gape limitation and prey growth rate and mortality1996Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 77, nr 3, s. 900-911Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study the effects of different predators on the behavior and dynamics of their prey, we compared the performance of perch (Perca fluviatilis) and the abundance of their prey resource in four lakes with two different types of piscivory. In two of the lakes, perch were the only fish species present and piscivory was restricted to cannibalism. In the other two lakes, perch co-occurred with piscivorous pike (Esox lucius). Pike grow to larger sizes and can capture larger prey than piscivorous perch. Therefore, perch reach a size refuge earlier in the lakes without pike. Perch in the lakes lacking pike used both the epilimnion and hypolimnion habitats of the lakes, and a high proportion of the perch occurred below the thermocline. In contrast, perch in the lakes with pike were mainly captured along the littoral zone and were never captured below the thermocline. This difference in habitat use was reflected in different diets of perch in the different lakes. Perch in the lakes with pike were also less abundant than those in the lakes lacking pike and the growth rates of individual perch and the densities of predator-sensitive prey (pelagic and littoral) were higher, indicating that the presence of pike resulted in decreased intraspecific competition in perch. Evidence for a behavioral response to predation risk was found in 1+ (1 yr old) perch, which was suggested to be due to predation risk from both larger perch and pike. It is hypothesized that the use of the cold-water hypolimnion habitat by perch in the lakes lacking pike was a response of perch to reduce metabolic demands under conditions of severe resource limitation. Differences in gape limitation between predators species are suggested to have major effects on size-dependent mortalities and growth rates in prey and thereby on overall community dynamics. Evidence for this latter effect was observed in differences in zooplankton size structure between the lakes with and without pike.

  • 46.
    Persson, Lennart
    et al.
    Umeå University, Department of Animal Ecology.
    Eklöv, Peter
    Umeå University, Department of Animal Ecology.
    PREY REFUGES AFFECTING INTERACTIONS BETWEEN PISCIVOROUS PERCH AND JUVENILE PERCH AND ROACH1995Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 76, nr 1, s. 70-81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In size-structured populations, interactions are strongly dependent on size-specific foraging and anti-predator capacities of the organism. Conflicting size-specific selection pressures over the ontogeny often have different effects on different species leading to asymmetries in competitive and predator-prey interactions. Habitat complexity is likely to affect such asymmetric interactions due to species/size-specific competitive abilities in different habitats and due to the fact that habitat structural complexity may act differently as a prey refuge for different species. We experimentally analyzed the impact of a piscivorous predator (adult perch, Perca fluviatilis) on performance of juvenile perch and roach (rutilus rutilus) at different levels of structural complexity (no structure, structure forming a partial refuge, and structure forming a complete refuge) in enclosures in an experimental pond. We measured predator diet and growth, prey fish habitat use, survival, diet and growth, and prey resource levels in different habitats. Prey fish (perch and roach) were found in the diet of piscivorous perch in no refuge and partial refuge treatments. Growth rate of the piscivorous perch decreased with increased refuge efficiency. Juvenile perch increased their proportional use of the structurally complex refuges in the presence of piscivorous perch and the survival increased with increased refuge efficiency (from partial to complete refuge). The diet of juvenile perch changed from predominantly cyclopoid copepods in the absence of predators to predominantly macroinvertebrates in the presence of predators. There was no effect of predator-induced habitat restriction on growth of juvenile perch. Roach survival also increased with increased refuge efficiency in the presence of predators, and roach survival in the refuge treatments did not differ from each other or from the treatments with predators absent. Predator-induced habitat restriction in roach was associated with a decreased growth of roach. Our results suggest that, compared to juvenile roach, juvenile perch may compensate more for lost foraging opportunity in the open water via increased exploitation of structure-associated prey in refuges. As a result, predator-induced habitat shifts by juvenile perch and roach may alter competitive interactions between the species. On the other hand, structural complexity may form an almost complete refuge for juvenile roach from predators and thereby affect the predator-prey relationships between piscivorous perch and juvenile perch and roach to the advantage of juvenile roach. The demonstrated effects of structural complexity on competitive and predator-prey interactions between perch and roach can be related to the two species' distributions in lakes with different degrees of structural complexity.

  • 47.
    Quevedo, Mario
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Svanbäck, Richard
    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.
    Intrapopulation niche partitioning in a generalist predator limits food web connectivity2009Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 90, nr 8, s. 2263-2274Artikel i tidskrift (Refereegranskat)
    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.

  • 48.
    Ragnarsson, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Beier, Ulrika
    Eklöv, Peter
    Holmgren, Kerstin
    Dispersal limitation and local processes - consequences for fish species richness and diversityManuskript (Övrigt vetenskapligt)
  • 49.
    Ragnarsson, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Eklöv, Peter
    Connectivity vs. local environment as structuring forces in lake fish communitiesManuskript (Övrigt vetenskapligt)
  • 50.
    Ragnarsson, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Eklöv, Peter
    Holmgren, Kerstin
    Fish species richness in lakes: the importance of local and regional processesManuskript (Övrigt vetenskapligt)
12 1 - 50 av 63
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf