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Behavioural and morphological responses to cannibalism in Arctic charr (Salvelinus alpinus)
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2005 (English)In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 7, no 5, 767-778 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Tucson: Evolutionary Ecology , 2005. Vol. 7, no 5, 767-778 p.
Keyword [en]
geometric morphometrics, phenotypic plasticity, predation risk, resource polymorphism
Identifiers
URN: urn:nbn:se:umu:diva-4841OAI: oai:DiVA.org:umu-4841DiVA: diva2:144093
Available from: 2005-11-18 Created: 2005-11-18 Last updated: 2017-12-14Bibliographically 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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http://www.evolutionary-ecology.com/issues/v07n05/kkar1833.pdf

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