FEMALE PROMISCUITY AND MATERNALLY DEPENDENT OFFSPRING GROWTH RATES IN MAMMALS |
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Authors: | Michael Garratt Robert C Brooks Jean‐François Lemaître Jean‐Michel Gaillard |
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Institution: | 1. Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, , Sydney, New South Wales, 2052 Australia;2. Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, Université de Lyon, , F‐69622 Villeurbanne, France |
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Abstract: | Conflicts between family members are expected to influence the duration and intensity of parental care. In mammals, the majority of this care occurs as resource transfer from mothers to offspring during gestation and lactation. Mating systems can have a strong influence on the severity of familial conflict—where female promiscuity is prevalent, conflict is expected to be higher between family members, causing offspring to demand more resources. If offspring are capable of manipulating their mothers and receive resources in proportion to their demands, resource transfer should increase with elevated promiscuity. We tested this prediction, unexplored across mammals, using a comparative approach. The total durations of gestation and lactation were not related to testes mass, a reliable proxy of female promiscuity across taxa. Offspring growth during gestation, however, and weaning mass, were positively correlated with testes mass, suggesting that offspring gain resources from their mothers at faster rates when familial conflict is greater. During gestation, the relationship between offspring growth and testes mass was also related to placenta morphology, with a stronger relationship between testes mass and growth observed in species with a less invasive placenta. Familial conflict could have a pervasive influence on patterns of parental care in mammals. |
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Keywords: | Fecundity life‐history evolution mating systems placenta sexual conflict |
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