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  • 1.
    Andersson, Jens
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Persson, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Behavioural and morphological responses to cannibalism in Arctic charr (Salvelinus alpinus)2005Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, nr 5, s. 767-778Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Question: Does cannibalism lead to resource polymorphism in young Arctic charr (Salvelinusalpinus, Pisces)?

    Hypothesis: Cannibals should evoke a low-activity morph that is well adapted to benthivorybut not planktivory, and which differs in morphology compared with a planktivorous morph.

    Methods: We reared young-of-the-year charr in laboratory aquaria with and without largercannibalistic charr present. Thereafter, we measured foraging efficiency on pelagic and benthicresources, swimming speed when foraging, and morphology of the young charr.

    Conclusions: Living among cannibals did not affect the morphology of the young charr. Italso did not affect the foraging efficiency of the young charr on the benthic resource. However,individuals from cannibal treatments swam closer and had lower foraging efficiency on thepelagic resource.

  • 2.
    Aunapuu, Maano
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland; Department of Natural Sciences, Finnmark University College, Alta, Norway.
    Oksanen, Tarja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Korpimaki, Erkki
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Intraguild predation and interspecific co-existence between predatory endotherms2010Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 12, nr 2, s. 151-168Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: According to the current predominant view, intraguild predation leads to the replacement of intermediate predators from highly productive habitats, whereas top predators and intermediate predators can co-exist in habitats with intermediate primary productivity. These predictions are contradicted by the observed abundance of intermediate predators in productive environments. But the predictions are derived by modelling interactions in food chains where the top predator is primarily adapted to exploit intermediate predators but also has some capacity to exploit the resources of the intermediate predators. We call this 'food chain omnivory'. In contrast, 'genuine intraguild predation' is the case where the two predators have shared tactics of resource acquisition, resulting in broadly overlapping prey preferences that is, the interacting predators belong to the same guild as defined by Root (1967).

    Questions: What are the effects of productivity on genuine intraguild predation? Do the predictions for food chain omnivory apply also to genuine intraguild predation'?

    Methods: We modelled genuine intraguild predation by using parameter values such that the intermediate predator and the basal prey were equally valuable to the top predator. We assumed that the basal prey was a herbivore, with a carrying capacity directly proportional to primary productivity and a habitat-specific intrinsic rate of population growth that increases asymptotically in response to increasing primary productivity.

    Results: With the above premises, intermediate predators can prevail even in highly productive habitat. Also, a priority effect is possible. Predictable replacement of intermediate predators by top predators requires that intermediate predators are much easier to find than basal prey. Stable co-existence requires biologically implausible parameter values.

    Conclusions: Genuine intraguild predation is a destabilizing force in food webs. The dynamics of genuine intraguild predation systems differ from those in food chain omnivory systems where the intermediate and top predators have different feeding tactics and, therefore, different prey preferences.

  • 3.
    Brännström, Åke
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Johansson, Jacob
    Loeuille, Nicolas
    Kristensen, Nadiah
    Troost, Tineke A
    Lambers, Reinier Hille Ris
    Dieckmann, Ulf
    Modelling the ecology and evolution of communities: a review of past achievements, current efforts, and future promises2012Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 14, nr 5, s. 601-625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The complexity and dynamical nature of community interactions make modelling a useful tool for understanding how communities develop over time and how they respond to external perturbations. Large community-evolution models (LCEMs) are particularly promising, since they can address both ecological and evolutionary questions, and can give rise to richly structured and diverse model communities.

    Questions: Which types of models have been used to study community structure and what are their key features and limitations? How do adaptations and/or invasions affect community formation? Which mechanisms promote diverse and stable communities? What are the implications of LCEMs for management and conservation? What are the key challenges for future research?

    Models considered: Static models of community structure, demographic community models, and small and large community-evolution models.

    Conclusions: Large community-evolution models encompass a variety of modelled traits and interactions, demographic dynamics, and evolutionary dynamics. They are able to reproduce empirical community structures. They have already generated new insights, such as the dual role of competition, which limits diversity through competitive exclusion yet facilitates diversity through speciation. Other critical factors determining eventual community structure are the shape of trade-off functions, inclusion of adaptive foraging, and energy availability. A particularly interesting feature of LCEMs is that these models not only help to contrast outcomes of community formation via species assembly with those of community formation via gradual evolution and speciation, but that they can furthermore unify the underlying invasion processes and evolutionary processes into a single framework.

  • 4.
    Brännström, Åke
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Johansson, Jacob
    Loeuille, Nicolas
    Kristensen, Nadiah
    Troost, Tineke
    Hille Ris Lambers, Reinier
    Dieckmann, Ulf
    Modelling the ecology and evolution of communities: a review of past achievements, current efforts, and future promises2012Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 14, nr 5, s. 601-625Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The complexity and dynamical nature of community interactions makemodelling a useful tool for understanding how communities develop over time and howthey respond to external perturbations. Large community-evolution models (LCEMs) areparticularly promising, since they can address both ecological and evolutionary questions, andcan give rise to richly structured and diverse model communities.Questions: Which types of models have been used to study community structure and what aretheir key features and limitations? How do adaptations and/or invasions affect communityformation? Which mechanisms promote diverse and stable communities? What are theimplications of LCEMs for management and conservation? What are the key challenges forfuture research?Models considered: Static models of community structure, demographic community models,and small and large community-evolution models.Conclusions: Large community-evolution models encompass a variety of modelled traits andinteractions, demographic dynamics, and evolutionary dynamics. They are able to reproduceempirical community structures. They have already generated new insights, such as the dual roleof competition, which limits diversity through competitive exclusion yet facilitates diversitythrough speciation. Other critical factors determining eventual community structure arethe shape of trade-off functions, inclusion of adaptive foraging, and energy availability. A particularly interesting feature of LCEMs is that these models not only help to contrast

  • 5. Crispo, Erika
    et al.
    DiBattista, Joseph D.
    Correa, Cristian
    Thibert-Plante, Xavier
    Department of Biology and Redpath Museum, McGill University, Montreal, Quebec, Canada.
    McKellar, Ann E.
    Schwartz, Amy K.
    Berner, Daniel
    De Leon, Luis F.
    Hendry, Andrew P.
    The evolution of phenotypic plasticity in response to anthropogenic disturbance2010Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 12, nr 1, s. 47-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Questions: Do evolutionary changes in phenotypic plasticity occur after anthropogenic disturbance? Do these changes tend to be increases or decreases in plasticity? How do these evolutionary patterns differ among taxa and trait types? Does evolution of plasticity change with time since the disturbance?

    Data incorporated: Evolutionary rates for plasticity estimated from 20 studies that have compared a plastic response in two or more populations, at least one of which had experienced an anthropogenic disturbance in nature and at least one of which had not.

    Method of analysis: We estimate evolutionary rates (darwins and haldanes) for plasticity for each study, which represent the amount of evolutionary change in plasticity. We then perform analyses of covariance, with the evolutionary rate numerator (amount of evolutionary change) as a response variable, taxa and trait type as predictor variables, and the amount of evolutionary time as a covariate.

    Conclusions:We find that plasticity has evolved in several cases, including both increases and decreases in the levels of plasticity following anthropogenic disturbances. The typical direction of this evolutionary response depends on an interaction between taxon and trait type. For instance, invertebrates sometimes show the evolution of increased  plasticity for life-history traits, but the evolution of decreased plasticity for morphological traits. Plants, on the other hand, show no trends in the direction of plasticity evolution.

  • 6.
    Dahlgren, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Oksanen, Tarja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Olofsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Hambäck, Peter A
    Department of Botany, Stockholm University, Stockholm, Sweden.
    Lindgren, Åsa
    Department of Botany, Stockholm University, Stockholm, Sweden.
    Plant defences to no avail?: Responses of plants of varying edibility to food web manipulations in a low arctic scrubland2009Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 11, s. 1189-1203Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: According to the Green World Hypothesis of Hairston, Smith, and Slobodkin,all plants are edible for some herbivores. Hence, the copious abundance of plant biomass,typical for terrestrial ecosystems, depends on the collective regulatory action of predators on the herbivore guild. According to the counterarguments of Polis and Strong, the defensive traits of terrestrial plants attenuate terrestrial trophic cascades to species-specific trickles,so elimination of predators might lead to increased abundance of inedible plants but will not influence community-level plant biomass.

    Question: Does the elimination of predators from a low arctic scrubland, with high-quality forage plants and poorly edible evergreen ericoids, lead to a reduction of community-level plant biomass or to an increased abundance of well-defended evergreen ericoids?

    Methods: In 1991, we introduced grey-sided voles (Myodes rufocanus) to islands, initially harbouring dense scrubland vegetation, and established permanent plots there. In 2000, we transplanted vegetation blocks from a large three-trophic-level island with voles and predators,to two-trophic-level islands with introduced voles but without resident predators, and also to vole-free one-trophic-level islands, and back to the three-trophic-level island. Vole densities were monitored by semi-annual live trapping. Vegetation was monitored by the point-frequency method.

    Results: In the absence of predators, vole densities increased 3.7-fold and the communitylevel plant biomass was decimated. The least palatable plant group, evergreen ericoids,suffered especially heavily, whereas palatable herbaceous plants increased in abundance. However, all three functional plant groups responded positively to the elimination of grey-sided voles.

    Conclusions: Our results corroborate the Green World Hypothesis, indicating that in the absence of predators, plant defences do not prevent runaway consumption of the vegetation.

  • 7.
    Dahlgren, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Olofsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Tarja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Plant defense at no cost?: The recovery of tundra scrubland following heavy grazing by grey-sided voles (Myodes rufocanus)2009Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 11, s. 1205-1216Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Evergreen ericaceous dwarf shrubs form a dominating component of low arctic and low alpine vegetation. They typically produce high contents of secondary chemicals such as phenolics. The primary function of these chemicals may be to defend the shrubs by making them less palatable to herbivores. Question: Does the production of secondary chemicals carry a fitness cost in terms of low growth rate and, therefore, low capacity to recover from past herbivory?

    Methods: In 2000, we constructed vole-proof exclosures on low arctic islands where vegetation had, since 1991, been heavily impacted by grey-sided voles. In 2000 and 2003,we surveyed the vegetation of the exclosures, of unfenced plots on the same islands, and of control plots on a vole-free island. We used the point-frequency method for vegetation surveys.

    Results: In the exclosures, the biomasses of most plant species increased, by and large, at the same pace. The two woody species, which increased most rapidly, were the maximally palatable bilberry (Vaccinium myrtillus) and the phenolics-laden, maximally unpalatable northern crowberry (Empetrum nigrum ssp. hermaprhoditum). The recovery rates of these species were similar.

    Conclusions: The high concentrations of phenolics typical for evergreen arctic dwarf shrubs do not carry any obvious cost in the form of reduced capacity for compensatory growth. The principle of trade-offs does not help to explain the variation in plant palatability.

  • 8.
    Mobley, Kenyon B.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ruiz, Rocio Colas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Johansson, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bokma, Folmer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    No evidence that stickleback spines directly increase risk of predation by an invertebrate predator2013Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 15, nr 2, s. 189-198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Some populations of stickleback have a reduced number and/or relative size of spines. Hypothesis: Macroinvertebrate predators such as dragonfly larvae cause selective pressure against spines by capturing more stickleback with pelvic spines than stickleback that are spineless. Organisms: Ninespine stickleback (Pungitius pungitius) and dragonfly larvae (Aeshna grandis). Methods: We used 10 stickleback, five with pelvic spines and five with their pelvic spines removed. We put them in containers with two dragonfly larvae. Every day for 4 days we monitored how many stickleback were captured by the larvae. We repeated this experiment ten times at two different densities of fish and predators. We also developed a model to determine whether selection for spinelessness can be distinguished from drift. Results: Dragonfly larvae caught as many stickleback with spines as without. The absence of spines was not associated with a decrease in predation risk. We substituted Bayesian estimates of the selection coefficient into quantitative genetic models of allele frequency change, and the results of the models suggest that the selective advantage of spine loss is so small that its effects cannot be distinguished from drift.

  • 9.
    Oksanen, Tarja
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Dahlgren, Jonas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Olofsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kyrö, Kukka
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    On the implications of currently available data concerning population fluctuations of arctic lemmings:  – reply to Gauthier et al. (2008)2009Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 11, s. 485-487Artikkel i tidsskrift (Fagfellevurdert)
  • 10.
    Reardon, Erin E.
    et al.
    Biology Department Biology Department, McGill University, Montreal, Quebec, Canada.
    Thibert-Plante, Xavier
    Biology Department and Redpath Museum, McGill University, Montreal, Quebec, Canada.
    Optimal offspring size influenced by the interaction between dissolved oxygen and predation pressure2010Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 12, nr 3, s. 377-387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Question: How does optimal size at the beginning of the juvenile stage vary with dissolved oxygen and aquatic predator pressure?

    Mathematical methods: An implicit model based on earlier offspring size and number optimality models, using empirical observations to motivate and interpret the results.

    Key assumptions: A stable, density-independent system with high parental care that maximizes maternal fitness, with respect to offspring size and number.

    Predictions: The model predicts a positive relationship between juvenile size and aquatic dissolved oxygen, with respect to maternal fitness and predation pressure. This prediction is based on observations in the literature that smaller fish are less sensitive to low dissolved oxygen and may use low dissolved oxygen habitats as predator refuges.

  • 11.
    Svanbäck, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bolnick, DI
    Intraspecific competition affects the strength of individual specialization: an optimal diet theory method2005Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, nr 7, s. 993-1012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

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

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

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

  • 12.
    Svanbäck, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Eklöv, Peter
    Genetic variation and phenotypic plasticity: Causes of morphological and dietary 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)
  • 13. Yamauchi, Atsushi
    et al.
    Takahashi, Daisuke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Center for Ecological Research, Kyoto University, Otsu, Japan.
    Environmental variation does not always promote plasticity: evolutionarily realized reaction norm for costly plasticity2014Inngår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 16, nr 8, s. 631-647Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Question: How does environmental variability influence evolutionarily realized phenotypic plasticity? Mathematical method: Optimization in a spatially fluctuating environment. Key assumptions: Either the maintenance cost of plasticity results from the amount of phenotypic response, or it results from the slope of the reaction norm. And there are two alternative types of state-specific benefit functions: either the benefit is maximal at an intermediate phenotype, or it is a monotonically increasing function of phenotype. Conclusion: Organisms may not respond to rare environmental states. In this case, environmental variability suppresses two indices of phenotypic plasticity, i. e. the range of plasticity and the maximum slope of the reaction norm.

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