Evol Ecol Res 4: 189-217 (2002)     Full PDF if your library subscribes.

Ontogenetic niche shifts and evolutionary branching in size-structured populations

David Claessen¹* and Ulf Dieckmann²

¹Institute for Biodiversity and Ecosystem Dynamics, Section of Population Biology, University of Amsterdam, PO Box 94084, 1090 GB Amsterdam, The Netherlands and ²Adaptive Dynamics Network, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria

Address all correspondence to David Claessen, IACR-Rothamsted, Biomathematics Unit, Harpenden, Herts AL5 2JQ, UK.
e-mail: david.claessen@bbsrc.ac.uk

ABSTRACT

There are many examples of size-structured populations where individuals sequentially exploit several niches in the course of their life history. Efficient exploitation of such ontogenetic niches generally requires specific morphological adaptations. Here, we study the evolutionary implications of the combination of an ontogenetic niche shift and environmental feedback. We present a mechanistic, size-structured model in which we assume that predators exploit one niche when they are small and a second niche when they are big. The niche shift is assumed to be irreversible and determined genetically. Environmental feedback arises from the impact that predation has on the density of the prey populations. Our results show that, initially, the environmental feedback drives evolution towards a generalist strategy that exploits both niches equally. Subsequently, it depends on the size-scaling of the foraging rates on the two prey types whether the generalist is a continuously stable strategy or an evolutionary branching point. In the latter case, divergent selection results in a resource dimorphism, with two specialist subpopulations. We formulate the conditions for evolutionary branching in terms of parameters of the size-dependent functional response. We discuss our results in the context of observed resource polymorphisms and adaptive speciation in freshwater fish species.

Keywords: Arctic char, bluegill, cichlids, evolution, feedback, ontogenetic niche shift, perch, population dynamics, resource polymorphism, roach, size structure.

DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.

 

        © 2002 David Claessen. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.