Quantifying direct and indirect maternal effects on male vervets rank post-dispersal

Abstract

Early life experiences have important fitness consequences across animals, with maternal environments playing a crucial role in some species survival and reproduction during adulthood. A potential pathway linking maternal behaviour with individual fitness is dominance rank, which in some primates - like cercopithecines - is maternally inherited during the juvenile period and strongly linked to individual social behaviour and reproductive success. While females of these species maintain their rank for life in their natal group, males disperse and must integrate into new dominance hierarchies. In this context, the long-term effects of maternal characteristics on male rank post-dispersal and the potential of males social behaviour in mediating this relationship remains unexplored. Using 16 years of data from a wild vervet monkey population (Chlorocebus pygerythrus), we tested the effects of maternal rank, grooming and proximity on the rank males acquired their first year post-dispersal. In addition, we measured the extent to which the males own social behaviour both pre- and post-dispersal mediate this relationship combining Bayesian social networks with mediation analyses. We did not find support for a mediating effect of males social behaviour on the relationship between maternal characteristics and male rank post-dispersal. Instead, we found that maternal characteristics influence males social behaviour during the juvenile period and that males own social behaviour post-dispersal (grooming out-degree) is related to their rank when they integrate into a new group. In addition, we found that consistency in males social behaviour pre- to post-dispersal is restricted to grooming behaviour, highlighting the different roles of proximity and grooming relationships in vervet societies. Taken together these results reveal very limited long-term effects of maternal characteristics on male behaviour during the heavily underexplored process of dispersal and the flexibility of male vervet social behaviour following a change in social environment.