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Letters to Nature

Nature 308, 358-360 (22 March 1984) | doi:10.1038/308358a0; Received 30 September 1983; Accepted 4 January 1984

Maternal dominance, breeding success and birth sex ratios in red deer

T. H. Clutton-Brock, S. D. Albon & F. E. Guinness

  1. Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
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That female vertebrates who are able to invest more than average in their offspring should produce male-biased sex ratios was first suggested by Trivers and Willard1 who reasoned that the breeding success of males is more variable than that of females and so may be more strongly influenced by parental investment. Their evidence for a positive association between maternal condition and birth sex ratios was unconvincing2,3 and no subsequent studies have produced conclusive evidence supporting their hypothesis4,8. We show here that, in polygynous red deer (Cervus elaphus), dominant mothers produce significantly more sons than subordinates and that maternal rank has a greater effect on the breeding success of males than females.