Individual dispersal decisions affect fitness via maternal rank effects in male rhesus macaques

Abstract

Natal dispersal may have considerable social, ecological and evolutionary consequences. While species-specific dispersal strategies have received much attention, individual variation in dispersal decisions and its fitness consequences remain poorly understood. We investigated causes and consequences of natal dispersal age in rhesus macaques (Macaca mulatta), a species with male dispersal. Using long-term demographic and genetic data from a semi-free ranging population on Cayo Santiago, Puerto Rico, we analysed how the social environment such as maternal family, group and population characteristics affected the age at which males leave their natal group. While natal dispersal age was unrelated to most measures of group or population structure, our study confirmed earlier findings that sons of high-ranking mothers dispersed later than sons of low-ranking ones. Natal dispersal age did not affect males’ subsequent survival, but males dispersing later were more likely to reproduce. Late dispersers were likely to start reproducing while still residing in their natal group, frequently produced extra-group offspring before natal dispersal and subsequently dispersed to the group in which they had fathered offspring more likely than expected. Hence, the timing of natal dispersal was affected by maternal rank and influenced male reproduction, which, in turn affected which group males dispersed to.

Developing individual differences in primate behavior: the role of genes, environment, and their interplay

“…A prominent example in NHPs is the migration from the natal group to a new group (natal dispersal). Migration is typically accompanied by increases in mortality or injury rates, decreases in access to resources, and social costs, i.e., the loss of social ties or rank (Dittus 1979;Weiß et al 2016). Following migration, male rhesus macaques show more fearful and less physically aggressive behavior than before (von Borell et al 2016), which is consistent with findings from captive pigtailed macaques, where individuals that are new to a facility are more cautious (Sussman et al 2014).…”

Dispersal strategies of juvenile pike (Esox luciusL.): Influences and consequences for body size, somatic growth and trophic position

“…The dispersal of an individual can have important consequences for individual fitness, population dynamics and spatial distributions (Clobert, Danchin, Dhondt, & Nichols, ). Movements from natal areas into habitats that provide enhanced foraging opportunities are common in many species, and this can have considerable social, ecological and evolutionary consequences (Weiß, Kulik, Ruiz‐Lambides, & Widdig, ). However, this natal dispersal can have considerable costs and tends to exist in trade‐offs with increased predation risk (Alcalay, Tsurim, & Ovadia, ; Halpin, ).…”

Which male and female characteristics influence the probability of extragroup paternities in rhesus macaques, Macaca mulatta?

“…Also in the present study we did not to detect a significant relationship between EGP and male age as well as a male’s previous reproductive success in his current group of residency or his natal status. The latter is noteworthy as a previous study on factors influencing natal dispersal found that more than two-thirds of the natal males that started reproducing before dispersal were observed to engage in EGPs (Weiß et al 2016), suggesting that it might be a means for natal males to find unrelated females willing to mate with them. Similarly, EGP was more common in a population of Australian magpies, Gymnorhina tibicen , with low rates of juvenile dispersal than in a population with high dispersal rates (Durrant & Hughes, 2005).…”

“…Research on the selective pressures that may drive males and/or females to seek EGPs has been conducted mainly in birds and, to a lesser extent, in mammals. For males, the benefits of mating outside their reproductive unit are rather straightforward as they can gain additional reproductive success through EGP (Birkhead & Møller, 1993; Fietz et al, 2000; Gibbs et al, 1990; Lawler, 2007; Trivers, 1972; Weiß, Kulik, Ruiz-Lambides, & Widdig, 2016). Benefits of EGP are less evident for females but may include both direct and indirect benefits such as the acquisition of good or compatible genes (blue tits, Parus caeruleus : Foerster, Delhey, Johnsen, Lifjeld, & Kempenaers, 2003; alpine marmots, Marmota marmota : Cohas, Yoccoz, Silva, Goossens, & Allainé, 2006; humans, Homo sapiens : Thornhill & Gangestad, 1993), avoiding costs related to inbreeding (banded mongoose, Mungos mungo : Nichols, Cant, & Sanderson, 2015), enhanced resource acquisition (Smuts, 1985; Greiling & Buss, 2000), or reduced risk of infanticide (reviewed in Wolff & MacDonald, 2004).…”