Female mate-choice drives the evolution of male-biased dispersal in a social mammal

Abstract

Dispersal has a significant impact on lifetime reproductive success, and is often more prevalent in one sex than the other. In group-living mammals, dispersal is normally male-biased and in theory this sexual bias could be a response by males to female mate preferences, competition for access to females or resources, or the result of males avoiding inbreeding. There is a lack of studies on social mammals that simultaneously assess these factors and measure the fitness consequences of male dispersal decisions. Here we show that male-biased dispersal in the spotted hyaena (Crocuta crocuta) most probably results from an adaptive response by males to simple female mate-choice rules that have evolved to avoid inbreeding. Microsatellite profiling revealed that females preferred sires that were born into or immigrated into the female's group after the female was born. Furthermore, young females preferred short-tenured sires and older females preferred longer-tenured sires. Males responded to these female mate preferences by initiating their reproductive careers in groups containing the highest number of young females. As a consequence, 11% of males started their reproductive career in their natal group and 89% of males dispersed. Males that started reproduction in groups containing the highest number of young females had a higher long-term reproductive success than males that did not. The female mate-choice rules ensured that females effectively avoided inbreeding without the need to discriminate directly against close kin or males born in their own group, or to favour immigrant males. The extent of male dispersal as a response to such female mate preferences depends on the demographic structure of breeding groups, rather than the genetic relatedness between females and males.

Brains, brawn and sociality: a hyaena's tale

“…Breeding males in both taxa are usually immigrants born elsewhere. As in virtually all cercopithecines, male hyaenas disperse voluntarily from their natal groups after puberty, whereas females are usually philopatric (Boydston, Kapheim, Van Horn, Smale, & Holekamp, 2005; Cheney & Seyfarth, 1983; Henschel & Skinner, 1987; Honer et al, 2007; Mills, 1990; Smale, Nunes, & Holekamp, 1997). As in many monkeys, relatedness is high within hyaena matrilines but, on average, clan members are only very distantly related due to high levels of male-mediated gene flow among clans (Van Horn, Engh, Scribner, Funk, & Holekamp, 2004).…”

Gene flow and natal dispersal in the Siberian flying squirrel based on direct and indirect data

“…To avoid inbreeding either males or females should disperse (Perrin and Mazalov 2000), but which sex disperses may depend on the level and type of intra-and inter-sexual competition (Perrin and Mazalov 2000;Lehmann and Perrin 2003;Leturque and Rousset 2004). In most mammals matechoice patterns and male competition for access to females may increase their dispersal distances (Dobson 1982;Perrin and Mazalov 2000;Honer et al 2007). …”

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

“…Recent research in birds and mammals presents a complex picture where individuals adjust their natal dispersal strategies according to individual, social and ecological conditions28910. In rodents, for instance, the likelihood of dispersing from the natal range was found to be influenced by factors such as resource availability11, group size12 or interactions among close relatives2.…”