The legacy of privilege: Social inheritance reverses sex differences in reproductive inequality in spotted hyenas

Marta Mosna, Alexandre Courtiol, Philemon Naman, Oliver Höner, Eve Davidian

Inequalities in reproductive success among females and males shape natural and sexual selec-tion, as well as genetic diversity. A key mechanism influencing reproductive inequality in humans and other animals is the social inheritance of privilege. Using a 29-year dataset spanning eight generations of spotted hyenas (Crocuta crocuta), a species in which social status is maternally inherited, we show that inheritance of privilege associated with high status not only shapes reproductive inequality but can reverse its typical sex bias. As in most polygynous species, reproductive inequality was lower among females than males when estimated on an annual basis. When measured across multiple generations, inequality increased in both sexes but disproportionately so among females. This effect was strong enough to reverse the sex bias in favor of females after a single generation. After only a few generations, most individuals thus descended from female ancestors that held the top-ranking position in their clan. Our study demonstrates the strong impact of the social inheritance of privilege on reproductive inequality by shaping differences between the sexes. We outline how reproductive inequality influences female-female and male-male competition and genetic evolution.