The Adaptive Dynamics of Altruism in Spatially Heterogeneous Populations

Le Galliard J-F, Ferriere R, & Dieckmann U (2003). The Adaptive Dynamics of Altruism in Spatially Heterogeneous Populations. IIASA Interim Report. IIASA, Laxenburg, Austria: IR-03-006


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We study the spatial adaptive dynamics of a continuous trait that measures individual investment in altruism. Our study is based on an ecological model of a spatially heterogeneous population from which we derive an appropriate measure of fitness. The analysis of this fitness measure uncovers three different selective processes controlling the evolution of altruism: the direct physiological cost, the indirect genetic benefits of cooperative interactions, and the indirect genetic costs of competition for space. In contrast with earliest suggestions, we find that the cost of competing for space with relatives exerts a negligible selective pressure against altruism. Our study yields a classification of adaptive patterns of altruism according to how the costs of altruism vary with an individuals investment in altruism (we distinguish between decelerating, linear, and accelerating dependence). The invasion of altruism occurs readily in species with accelerating costs, but large mutations are critical for altruism to evolve in selfish species with decelerating costs. Strict selfishness is maintained by natural selection only under very restricted conditions. In species with rapidly accelerating costs, adaptation leads to an evolutionarily stable rate of investment in altruism that decreases smoothly with the level of mobility. A rather different adaptive pattern emerges in species with slowly accelerating costs: high altruism evolves at low mobility, whereas a quasi-selfish state is promoted in more mobile species. The high adaptive level of altruism can be predicted solely from habitat connectedness and physiological parameters that characterize the pattern of cost. We also show that environmental changes that cause increased mobility in those highly altruistic species can beget selection-driven self-extinction, which may contribute to the rarity of social species.

Item Type: Monograph (IIASA Interim Report)
Research Programs: Adaptive Dynamics Network (ADN)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 02:16
Last Modified: 06 Nov 2016 07:20

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