Sex ratio in the social hymenoptera: a population-genetics study of long-term evolution

Article Abstract:

The evolutionarily stable state (ESS) of the sex ratio in social Hymenoptera was investigated through the analysis of a population-genetics model of queen and worker fitness. Analysis of the model showed that two possible ESSs were responsible for the resolution of conflict between the queen and her workers on the production of male and female offspring, and thus, the survival of insect colonies. One stable evolution model was a set of isolated points with less than the optimum productivity while the other was a continuum of points with maximum productivity.

Population genetics, Hymenoptera, Sex distribution (Demography)

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Inference of pair bonds from capture data based on low variation of the sex ratio among catches

Article Abstract:

A developed statistical procedure determines the presence of pairs and estimates paired individual proportion in an animal sample captured without disruption of their spatial association. The method uses the counts by sex of specimens based on observations that paired individuals of nonogamous animal species don not stray far from their mate and home ground. It is a good alternative when observations of pairing or recapture of same individual is not possible. This statistical method proves effective when applied to a small sample of bearded tit.

Analysis, Passeriformes, Perching birds, Bird populations

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Differential dispersal, local resource competition, and sex ratio variation in birds

Article Abstract:

Competition for local resources resulting from the differential distribution of male and female offspring could be a selection constraint that determines the male to female ratio in the progenies of birds. Anseriform natal sex ratio is biased for males while that of passerines is biased for females. A hypothesis based on competition for local resources should predict this. Empirical evidence for such a hypothesis is presented.

Birds, Animal reproduction

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