Deakin University

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Adjustment of offspring sex ratios in relation to the availability of resources for philopatric offspring in the common brushtail possum

journal contribution
posted on 2001-10-07, 00:00 authored by C N Johnson, M Clinchy, A C Taylor, C J Krebs, P J Jarman, A Payne, Euan RitchieEuan Ritchie
The local-resource-competition hypothesis predicts that where philopatric offspring compete for resources with their mothers, offspring sex ratios will be biased in favour of the dispersing sex. This should produce variation in sex ratios between populations in relation to differences in the availability of resources for philopatric offspring. However, previous tests of local resource competition in mammals have used indirect measures of resource availability and have focused on sex-ratio variation between species or individuals rather than between local populations. Here, we show that the availability of den sites predicts the offspring sex ratio in populations of the common brushtail possum. Female possums defend access to dens, and daughters, but not sons, occupy dens within their mother's range. However, the abundances of possums in our study areas were determined principally by food availability. Consequently, in food-rich areas with a high population density, the per-capita availability of dens was low, and the cost of having a daughter should have been high. This cost was positively correlated with male bias in the sex ratio at birth. Low per capita availability of dens was correlated with male bias in the sex ratio at birth.



Royal Society of London : proceedings B : biological sciences






2001 - 2005


Royal Society Publishing


London, Eng.





Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2001, Royal Society