Variation in offspring sex ratio among individual Weddell seal (Leptonychotes weddellii) females of different quality |
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Authors: | Kelly M. Proffitt Robert A. Garrott Jay J. Rotella |
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Affiliation: | (1) Department of Ecology, Montana State University, 310 Lewis Hall, Bozeman, MT 59717, USA |
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Abstract: | The Trivers–Willard model predicts that in polygynous species, superior-quality females will maximize their fitness by producing male offspring. Using a sample of 1,780 Weddell seal (Leptonychotes weddellii) pups recorded over 31 years, we investigated relationships between offspring sex ratio and maternal age, reproductive experience, an index of maternal lifetime reproductive output, and annual environmental variations. We found evidence that females with higher index of lifetime reproductive output were more likely to produce male than female offspring but found only weak evidence that large-scale environmental variations influenced sex ratios. Our results suggest that mothers manipulate offspring sex to maximize their own fitness, and inherent maternal quality may influence offspring sex. These findings support the Trivers–Willard sex-allocation model. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Sex ratio Trivers– Willard model Lifetime reproductive output Leptonychotes weddellii |
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