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

Abstract

Extragroup paternity (EGP) is found across a wide range of species and may entail reproductive benefits, but may also entail costs to both sexes. While population and group parameters affecting the degree of EGPs are relatively well established, less is known about the individual characteristics that make males and females engage in alternative reproductive tactics such as EGP. Applying a combination of long-term demographic and genetic data from the rhesus macaque population of Cayo Santiago (Puerto Rico, U.S.A.), we investigate which male and female characteristics influence the probability of EGP to better understand the circumstances that shape the distribution and occurrence of EGP. Our results show that, against our expectations, higher-ranking females were more likely to produce EGP offspring than lower- ranking females. The probability of producing extragroup offspring was not significantly related to female or male age, male tenure or previous reproductive success. Furthermore, genetic relatedness between the parents did not affect the production of extragroup offspring, but extragroup offspring were more frequently produced early rather than late in a given mating season. Altogether, our analysis suggests that individual attributes and seasonal aspects create different opportunities and preferences for engaging in EGP as an alternative reproductive tactic. The observed patterns of EGP in rhesus macaques appear to be consistent with female mate choice for genetic benefits, which needs to be confirmed in future studies.

Socio-ecological conditions and female infidelity in the Seychelles warbler

“…While some studies have found a positive effect of pair relatedness on EPP (e.g., Blomqvist et al 2002; Cohas et al 2006; Freeman-Gallant et al 2006; Leclaire et al 2013), others have shown no effect (e.g., Schmoll et al 2005; Edly-Wright et al 2007; Barati et al 2018). Mixed evidence has resulted also from meta-analyses (in favor: Arct et al 2015; against: Ackay and Roughgarden 2007) and from research on polygynandrous species, which addressed the effect of female–male relatedness (within a group) on EGP levels (e.g., Nichols et al 2015 versus Ruiz-Lambides et al 2018). In the Seychelles warbler, we only detected a positive relationship between genetic relatedness and EGP likelihood for subordinate mothers.…”