Advances in our understanding of mammalian sex‐biased dispersal

Abstract

Sex-biased dispersal is an almost ubiquitous feature of mammalian life history, but the evolutionary causes behind these patterns still require much clarification. A quarter of a century since the publication of seminal papers describing general patterns of sex-biased dispersal in both mammals and birds, we review the advances in our theoretical understanding of the evolutionary causes of sex-biased dispersal, and those in statistical genetics that enable us to test hypotheses and measure dispersal in natural populations. We use mammalian examples to illustrate patterns and proximate causes of sex-biased dispersal, because by far the most data are available and because they exhibit an enormous diversity in terms of dispersal strategy, mating and social systems. Recent studies using molecular markers have helped to confirm that sex-biased dispersal is widespread among mammals and varies widely in direction and intensity, but there is a great need to bridge the gap between genetic information, observational data and theory. A review of mammalian data indicates that the relationship between direction of sex-bias and mating system is not a simple one. The role of social systems emerges as a key factor in determining intensity and direction of dispersal bias, but there is still need for a theoretical framework that can account for the complex interactions between inbreeding avoidance, kin competition and cooperation to explain the impressive diversity of patterns.

A comparative approach to testing hypotheses for the evolution of sex‐biased dispersal in bean beetles

“…For example, polygynous mating systems (where a single male can fertilize multiple females) are typically associated with strong male competition for females. The occurrence of male‐biased dispersal in taxa with polygynous mating systems is therefore consistent with the kin competition hypothesis, because male dispersal would enhance inclusive fitness, all else equal (Greenwood 1980; Handley and Perrin 2007; Dobson 2013). Thus, the kin competition hypothesis predicts that sex‐biased dispersal reduces competition between relatives, although it need not reduce competition overall.…”

“…The direction and magnitude of sex bias in dispersal varies across taxa and may be associated with taxonomic groups and / or mating systems. For example, dispersal tends to be female‐biased in monogamous taxa such as birds and male‐biased in promiscuous taxa such as mammals (Greenwood 1980; Pusey 1987; Handley and Perrin 2007; Dobson 2013). Sex bias in dispersal can have important implications for the spread of invasive organisms (Miller et al.…”

“…2004). Understanding the selective forces that favor sex‐biased dispersal has been a persistent challenge (Handley and Perrin 2007; Dobson 2013). …”

Postdispersal nepotism in male long‐tailed macaques (Macaca fascicularis)

“…2009, 2010), are generally built on kinship. Dispersing males, in contrast, often disperse before they become reproductively active (Lawson Handley and Perrin 2007), making it more difficult to maintain kin associations. In species with litters, fraternal littermates can co‐disperse and thus form lasting alliances (e.g.…”

Introduction history overrides social factors in explaining genetic structure of females in Mediterranean mouflon

“…These sex‐specific behaviors lead to a higher spatial stability for females than for males. An interesting way to go further in the study of this sex‐biased reproductive dispersal would be to investigate mtDNA and Y‐chromosome, that is nonrecombining sex‐specific markers (Handley & Perrin, 2007). …”