Saturday, May 31, 2008

Monogamy and Eusociality

Is high relatedness a cause or effect of eusociality? In this paper that just came out in Science, they find through some phylogenetic analyses and mating data among social insects that monogamy (which maximizes relatedness) is ancestral for all lineages, meaning that kin selection is likely a cause of eusociality (I have no idea of the details of how they did this). It's somewhat disappointing and surprising that they make no mention of humans or the paper by Bowles which hints at the relationship between monogamy (reproductive leveling), relatedness and kin selection and group selection, although in a different way.

Ancestral Monogamy Shows Kin Selection Is Key to the Evolution of Eusociality
William O. H. Hughes, Benjamin P. Oldroyd, Madeleine Beekman, Francis L. W. Ratnieks
Science 30 May 2008: Vol. 320. no. 5880, pp. 1213 - 1216
Abstract: Close relatedness has long been considered crucial to the evolution of eusociality. However, it has recently been suggested that close relatedness may be a consequence, rather than a cause, of eusociality. We tested this idea with a comparative analysis of female mating frequencies in 267 species of eusocial bees, wasps, and ants. We found that mating with a single male, which maximizes relatedness, is ancestral for all eight independent eusocial lineages that we investigated. Mating with multiple males is always derived. Furthermore, we found that high polyandry (>2 effective mates) occurs only in lineages whose workers have lost reproductive totipotency. These results provide the first evidence that monogamy was critical in the evolution of eusociality, strongly supporting the prediction of inclusive fitness theory.

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