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Plastic reources polymorphism: effects or resource availability on Arctic char (Salvelinus alpinus) morphology
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Department of Aquaculture, Swedish University of Agricultural Sciences, Sweden.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Netherlands.
2005 (English)In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 85, no 3, 341-351 p.Article in journal (Refereed) Published
Abstract [en]

Resource polymorphism has been suggested to be a platform for speciation. In some cases resource polymorphism depends on phenotypic plasticity but in other cases on genetic differences between morphotypes, which in turn has been suggested to be the ongoing development of a species pair. Here we study environmentally induced morphological differences in two age classes of Arctic char (Salvelinus alpinus) influencing char performance and diet in relation to resource availability. We found that structurally complex habitats with relatively lower zooplankton densities gave rise to individuals with a deeper body, and a downward positioned tip of the snout compared with individuals from structurally simple habitats with relatively higher zooplankton densities for both age classes. Environment also had an effect on foraging efficiency on zooplankton, with fish from structurally simple habitats had a higher foraging rate than fish from structurally complex habitats. Diet analyses showed that resource use in char mainly depends on the relative abundance of different resources. Therefore, to gain further understanding of resource polymorphism we suggest that future studies must include population dynamic feedbacks by the resources on the consumers.

Place, publisher, year, edition, pages
London: Acad. P. , 2005. Vol. 85, no 3, 341-351 p.
Keyword [en]
diet, foraging efficiency, geometric morphometrics, habitat, planktivory, resource densities
Identifiers
URN: urn:nbn:se:umu:diva-4842DOI: 10.1111/j.1095-8312.2005.00501.xOAI: oai:DiVA.org:umu-4842DiVA: diva2:144094
Available from: 2005-11-18 Created: 2005-11-18 Last updated: 2011-04-20Bibliographically approved
In thesis
1. The development of resource polymorphism – Effects of diet, predation risk and population dynamical feedbacks.
Open this publication in new window or tab >>The development of resource polymorphism – Effects of diet, predation risk and population dynamical feedbacks.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the evolution of individuals within a species adapted to utilize specific resources, i.e. resource polymorphism. Although a well-known phenomenon, the understanding of the mechanisms behind is not complete. Considering the ruling theories, resource polymorphism is suggested to depend on severe competition for resources, the presence of open niches to be occupied leading to a reduction in competition, and disruptive selection where generalist are out-competed due trade-offs in foraging efficiency for different prey. In order to study resource polymorphism, I have used fish as the animal group in focus and the methods I have used range over laboratory experiments, field experiments, literature surveys and theoretical modelling.

In my work, I have showed that different resource use induces different body shapes and that the rate of change is dependent of the encounter rate of different resources. The induced body changes partly led to increased foraging efficiency but surprisingly I did not find any trade-offs due to specialization. However, when studying predation risk in relation to resource polymorphism, my studies point towards that resource use and predation risk may act as balancing factors in such a way that disruptive selection can take place.

My work also shows that population feedbacks have to be explored when considering the evolution of resource polymorphism. In pond and field experiments, I found that changes in resource densities affected the actual resource use despite previous adaptations to certain resources. By performing a literature survey, I found that cannibalism indirectly by its effect on population dynamics seems to facilitate the evolution of resource polymorphism. Modelling a size-structured population, I found that resource dynamics were stabilized, and the relative availability of different resources was levelled out due to cannibalism.

Taken together, my studies strongly suggest that to understand the development of resource polymorphism in consumer populations, future studies have to include the effect of a dynamic environment both with respect to resources and predators.

Place, publisher, year, edition, pages
Umeå: Ekologi, miljö och geovetenskap, 2005. 21 p.
Keyword
body shape, diet, geometric morphometrics, phenotypic plasticity, population dynamics, predation risk, resource polymorphism, size structured populations
Identifiers
urn:nbn:se:umu:diva-639 (URN)91-7305-867-X (ISBN)
Public defence
2005-12-09, 10:00
Supervisors
Available from: 2005-11-18 Created: 2005-11-18 Last updated: 2012-05-14Bibliographically approved

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Persson, Lennart

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