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Updated: Mar 6, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
Sex ratio and intrasexual kin competition in mammals
Andrew Cockburn1, Michelle P Scott2, Chris R Dickman1
1Department of Zoology, Australian National University, GPO Box 4, 2601, Canberra, ACT, Australia.
Abstract:
Asymmetries in both intrasexual competition and generation overlap occur in Antechinus (Dasyuridae; Marsupialia). We show that the range of interpopulation variation in the sex ratio of pouch young spans and exceeds the range of sex ratios at birth hitherto recorded from eutherians (Clutton-Brock and Albon 1983). Although postweaning dispersal and male mortality are similar among all Antechinus populations, interpopulation variance in female longevity leads to variable duration of mother/daughter interaction. As this duration increases, parental investment is increasingly biased toward males, supporting the view that local competition among female kin for resources may influence mammalian sex ratios.
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