Evolution of Sex-Biased Dispersal

Abstract

Dispersal is central in ecology and evolution because it influences population regulation, adaptation, and speciation. In many species, dispersal is different between genders, leading to sex-biased dispersal. Several theoretical hypotheses have been proposed to explain the evolution of this bias: the resource competition hypothesis proposed by Greenwood, the local mate competition hypothesis, and the inbreeding avoidance hypothesis. Those hypotheses argued that the mating system should be the major factor explaining the direction of such bias. Sociality and the presence of handicap in genders (exaggerated sexual characters or parental care) have recently been proposed to be linked with the direction of this bias. We tested these expected coevolutions using a database of 257 species. Based on phylogenetic approaches, our findings marginally corroborated Greenwood’s hypothesis by showing relationships between the direction of sex-biased dispersal, mating systems, and territoriality. More importantly, our results highlighted that the evolution of this bias was more linked to parental care and sexual dimorphism. These traits were also found to be associated with mating systems, suggesting that sexual asymmetry in morphology and parental care might be the main determinant of the evolution of sex-biased dispersal across species and not mating systems per se, as proposed in Greenwood’s hypothesis.

Sex‐biased breeding dispersal is predicted by social environment in birds

“…We collected sex‐specific dispersal data (both from census and capture–recapture studies) by searching primary publications in peer‐reviewed journals and books and also by tracking back references cited by previous reviews and phylogenetic analyses (Mabry et al., 2013; Trochet et al., 2016; for further details, see Appendices S1–S3). Following Clobert (2012), we defined natal dispersal distance as the average movement of individuals from their birth site to the site of reproduction.…”

“…(2013) and Trochet et al. (2016) who reported information on 56 and 46 sex‐specific dispersal distances in birds, respectively. Note that neither Mabry et al.…”

“…Therefore, the frequency and extent of dispersal movements tend to be sex‐biased (Clobert et al., 2001). Indeed, sex‐biased dispersal has been documented for several taxa including invertebrates, reptiles, birds, and mammals (Clobert et al., 2001; Greenwood, 1980; Trochet et al., 2016), although its underlying ecological and evolutionary causes and consequences are still poorly known. For instance, in birds, females tend to disperse farther than males, whereas in mammals, the reverse appears to be the case (Greenwood, 1980; Clarke, Sæther, & Røskaft, 1997; Mabry, Shelley, Davis, Blumstein, & Van Vuren, 2013.…”

“…For example, higher inbreeding results in an increase in homozygosity, which is associated with fitness loss and with inbreeding depression in normally outbred populations (Pusey, 1987). However, recent investigations only reported weak effects of inbreeding avoidance on the direction of sex‐biased dispersal (Guillaume & Perrin, 2009; Trochet et al., 2016). …”

“…Although some comparative studies of avian dispersal have been previously performed, they were either qualitative (Clarke et al., 1997; Greenwood, 1980) or did not distinguish between natal and breeding dispersal (Mabry et al., 2013; Trochet et al., 2016). We aim to fill this knowledge gap by specifically testing whether the magnitude and the direction of sex‐biased natal and breeding dispersal in birds are positively associated with the intensity of sexual selection (using several metrics including social mating system, frequency of extra‐pair paternity (EPP), SSD, and plumage coloration) and with the amount of sex differences in parental care.…”