Male reproductive skew in multimale social groups of Verreaux’s Sifaka (Propithecus verreauxi) at Kirindy Mitea National Park, Madagascar
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In many non-human primates living in multimale groups, reproductive success among males is usually skewed towards dominant individuals. Models of reproductive skew have proposed that dominant males’ reproductive success depends on their ability to monopolize female reproduction. These models predict that female monopolization by males depends on the number of receptive females that can be monitored by the dominant male and the number of males in the group that might constitute competitors for access to females. However, female reproductive strategies might hinder dominant males’ monopolization of matings and provide reproductive opportunities to non-dominant and extra-group males. In this study, we explored male reproductive skew in a population of Verreaux’s sifaka (Propithecus verreauxi) living in Kirindy Mitea National Park, Madagascar. Using genetic data, we analyzed maternity paternity for 32 individuals born in five different social groups between 2007 and 2012, and examined whether the distribution of paternity was influenced by demographic variables or social factors such as the number of males, the number of females, male dominance rank, and male tenure. We successfully assigned maternity and paternity to 28 and 27 individuals, respectively, and found that 85% of offspring we born to either the single male resident in the group at the time of conception or to the resident dominant male in multimale groups. Although in groups with more than one resident male the dominant male sired 71% of offspring, this result was not significantly different from an even distribution of paternities among dominant and subordinates. In general, male reproductive skew in our study population is not significantly biased towards males either that are more dominant or that have had longer tenure in the group. Although dominant males in multimale groups were unable to completely monopolize female matings, subordinates’ reproductive success did not increase when more females were present in the group, contradicting previous models of male reproductive skew. Our study suggests that in this female-dominant species, females’ mating decisions may play an important role in paternity distribution due to the nature of dominance relationships that prevents males from monopolizing and controlling female reproduction entirely.