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Evolution in fickle environments: dispersal, specialization, and the problem of heterogeneity.

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Call No.	QL391.N4 F75 2002
Author	Friedenberg, Nicholas Alexander
Title	Evolution in fickle environments: dispersal, specialization, and the problem of heterogeneity.
Date	2002
Abstract	All ecological theories regarding the distribution and relative abundance of species refer to organisms' abilities to utilize an environment and (sometimes implicitly) their ability to colonize and re-colonize habitats that change in character or quality over space and through time. The concepts of specialization and dispersal are not only the underpinnings of our understanding of ecological patterns; they have both been used to explain the maintenance of genetic diversity in evolutionary models. While the evolution of dispersal is well understood from a theoretical perspective, there has been no experimental validation of this theory. Additionally, while the evolution of specialization is known to be a product of the balance between dispersal rates and local selection, little attention has been paid to the fact that specialization and dispersal are themselves coevolving characters sensitive to the same environmental forces. Using the bacteriophagous soil nematode, Caenorhabditis elegans , in patchy microcosms, I demonstrate that the magnitude and synchrony of spatiotemporal fitness heterogeneity influences the evolution of dispersal. I then develop a model for the effect of spatiotemporally random extinctions on competition between a capitalist species, one which excels at converting local resources into offspring, and a vagabond species, one that is less fecund but excels at dispersing between habitat patches. The model predicts that the number of individuals in a patch, a local feature of the environment, determines the rate at which the capitalist excludes the vagabond when patches do not go extinct. Experiments with C. elegans in microcosms with large and small patches confirm this prediction. The model predicts that the number of patches, a regional feature of the environment, will determine the outcome of competition only when patches fluctuate randomly. This prediction is also upheld by the experiments. I then use an individual-based model to show that the evolution of specialization and dispersal is negatively correlated in heterogeneous environments; spatiotemporal heterogeneity favors increased dispersal and reduced specialization. One implication of these collective findings is that an increase in the magnitude of environmental fluctuations will selectively favor vagile generalist species over sessile specialists with more restricted ranges.
Description	1 online resource (xi, 129 leaves) : illustrations
Format	application/pdf
Advisor	McPeek, Mark A.
Subject	Caenorhabditis elegans -- Ecology. ; Ecological heterogeneity. ; Evolution (Biology). ; Adaptation (Biology). ; Nematodes -- Dispersal.
College	Dartmouth College -- Department of Biological Sciences.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D)--Dartmouth College.
Copyright	In Copyright. This material is protected by copyright and/or related rights. You are free to use this material in any way that is permitted by copyright law that applies to your use. For other uses, you need to obtain permission from the rights-holder(s). http://rightsstatements.org/page/InC/1.0/
DOI	https://doi.org/10.1349/ddlp.2728

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Evolution in fickle environments: dispersal, specialization, and the problem of heterogeneity.

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