American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

ASN Address:“The ecological dynamics of natural selection: Traits and the coevolution of community structure”

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Mark A. McPeek

Natural selection is caused by the interactions of a population of individuals with their environment and other species, but most studies of natural selection simplify or ignore these ecological causes to focus on the genetic consequences of evolution. In this paper, classic models combining species interactions with quantitative genetics are used to explore how changes in the environment and interactions with other species shape the dynamics and outcome of natural selection. Not surprisingly, the outcome of natural selection changes both as the interaction partners change and as the environmental background changes. However, the analysis of these models provide a sound guide for the ecological dynamics of natural selection on very short and very long time scales. This analysis also generates a number of important testable predictions about the action of natural selection in different ecosystems, including that natural selection should be stronger in more productive and more benign ecosystems, and in ecosystems where interactions among species should be more important. Consequently, natural selection should also cause species that fill the same role in an ecosystem to evolve greater differences from one another in more productive and benign ecosystems. This latter prediction suggests an evolutionary hypothesis for why the tropics harbor many more species than temperate and polar regions of the globe. Read the Article