The effect of sex‐biased dispersal on opposite‐sexed spatial genetic structure and inbreeding risk

Abstract

Natal sex-biased dispersal has long been thought to reduce the risk of inbreeding by spatially separating opposite-sexed kin. Yet, comprehensive and quantitative evaluations of this hypothesis are lacking. In this study, we quantified the effectiveness of sex-biased dispersal as an inbreeding avoidance strategy by combining spatially explicit simulations and empirical data. We quantified the extent of kin clustering by measuring the degree of spatial autocorrelation among opposite-sexed individuals (FM structure). This allowed us to systematically explore how the extent of sex-biased dispersal, generational overlap, and mate searching distance, influenced both kin clustering, and the resulting inbreeding in the absence of complementary inbreeding avoidance strategies. Simulations revealed that when sex-biased dispersal was limited, positive FM genetic structure developed quickly and increased as the mate searching distance decreased or as generational overlap increased. Interestingly, complete long-range sex-biased dispersal did not prevent the development of FM genetic structure when generations overlapped. We found a very strong correlation between FM genetic structure and both FIS under random mating, and pedigree-based measures of inbreeding. Thus, we show that the detection of FM genetic structure can be a strong indicator of inbreeding risk. Empirical data for two species with different life history strategies yielded patterns congruent with our simulations. Our study illustrates a new application of spatial genetic autocorrelation analysis that offers a framework for quantifying the risk of inbreeding that is easily extendable to other species. Furthermore, our findings provide other researchers with a context for interpreting observed patterns of opposite-sexed spatial genetic structure.

Fine‐scale genetic structure reflects sex‐specific dispersal strategies in a population of sociable weavers (Philetairus socius)

“…First, spatially clustered kinship generates a risk of potentially deleterious inbreeding (Keller & Waller ; Blyton et al . ). Previous studies on cooperatively breeding birds have shown that dispersal by either both sexes or, more commonly, by females can be an efficient mechanism to avoid inbreeding (Walters et al .…”

“…Such spatial clustering of relatives also has important consequences in terms of mate choice. First, spatially clustered kinship generates a risk of potentially deleterious inbreeding (Keller & Waller 2002;Blyton et al 2015). Previous studies on cooperatively breeding birds have shown that dispersal by either both sexes or, more commonly, by females can be an efficient mechanism to avoid inbreeding (Walters et al 2004;Blackmore et al 2011;Nelson-Flower et al 2012).…”

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

“…extra-group mating52. Extra-group paternity (EGP) is common in mammals, accounting for a mean of 29.2% of offspring in 20 of 26 investigated species53; in rhesus macaques, levels of EGP range from 16–36% (Ruiz-Lambides unpublished data)5354.…”

Sex‐biased dispersal and spatial heterogeneity affect landscape resistance to gene flow in fisher

“…The presence of overlapping generations, more realistic of wild populations, extends the genetic signal of sex‐biased dispersal as mothers and daughters cluster geographically, while male offspring disperse farther from their natal area (Blyton et al. ). Juvenile dispersal of fisher from their natal areas usually begins in mid‐late winter (~10 months post‐birth), with the majority of juvenile dispersal occurring from February to September (Lofroth et al.…”

“…With nonoverlapping generations, microsatellite markers can detect sex-biased dispersal when individuals are sampled after dispersal, but before reproduction, when alleles from dispersers will be transmitted to its offspring. The presence of overlapping generations, more realistic of wild populations, extends the genetic signal of sex-biased dispersal as mothers and daughters cluster geographically, while male offspring disperse farther from their natal area (Blyton et al 2015). Juvenile dispersal of fisher from their natal areas usually begins in mid-late winter (~10 months post-birth), with the majority of juvenile dispersal occurring from February to September (Lofroth et al 2010, Sweitzer et al 2015.…”