Dissertation Research: The Effects of Ecological Constraints on Polygyny in Argentine Ants

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9976725 Palumbi The ecological constraints hypothesis proposes that competition and/or habitat saturation promotes the evolution of polygyny (multiple queens) in colonies of eusocial insects that have low relatedness between nest mates. To test this hypothesis, this study will compare colonies from three field populations of the Argentine ant, Linepithema humile: an introduced population with no competition, an introduced population coexisting with a major competitor, and a native population. Ecological data including nest characteristics and density of nests will be measured in the field, and the genetic variables of queen number and reproductive skew will be measured using microsatellite analysis. Comparing data from the three populations will reveal how the ecology, social structure, and degree of polygyny of this species changes with different levels of ecological constraint. The results of this study will expand our traditional view of the evolution of cooperation as a process of kin selection by exploring how cooperation can evolve between distantly related individuals. Determining how an important life history trait like polygyny varies with ecological factors is the first step to understanding the many ways social organisms may be able to adapt to their environment. The significance of this study reaches beyond the scope of eusocial insects. By relating demographic features with internal properties of societies, this study tests the underlying forces behind the proximate and ultimate causes of a number of evolutionary puzzles including kin conflict in complex societies, reproductive skew, communal breeding, and the evolution of social life itself.