Abstract
In most mammals dispersal is male-biased and in many polygynous ungulates female philopatry and matrilineal grouping involve small-scale genetic structure. We have through sex-related differences in microsatellite allele distribution addressed sex-biased dispersal in a spatially expanding northern ungulate population. The Norwegian red deer population (Cervus elaphus atlanticus) has the last hundred years grown substantially and expanded spatially after a major decline from 300 to 100 years ago. Previous Bayesian analyses suggest a present division of genetic variation into five geographically separated subpopulations. Among these subpopulations the overall Fst values were 0.067 (SE=0.014) for males and 0.094 (SE=0.017) for females. Pairwise Fst values were significantly higher for females than males, demonstrating a stronger genetic structure among females, and that dispersal has been lower in females than males. Accordingly, a higher number of male than female first generation dispersers were identified among the five subpopulations using Bayesian assignment with prior population information, but significantly so only with relaxed stringency levels of assignment. The identified male-biased dispersal distances varied from 30 to 300 kilometers suggesting male biased dispersal on a large scale in red deer.
Highlights
Dispersal is sex-biased when the members of one sex are faithful to their natal range and / or matrilineal group, while members of the other sex are more likely to disperse (Prugnolle & de Meeus, 2002)
The differences between the sexes in genetic structure estimated from microsatellite markers suggest that dispersal is more limited in females than males and that dispersal is male-biased between the subpopulations of the Norwegian red deer population
Bayesian analyses offer a powerful alternative for quantitative estimates of sexbiased dispersal (Handley & Perrin, 2007), and the higher number of identified male than female first generation dispersers between subpopulations provide strong support for a malebiased dispersal on a large scale
Summary
Dispersal is sex-biased when the members of one sex are faithful to their natal range and / or matrilineal group (philopatric), while members of the other sex are more likely to disperse (Prugnolle & de Meeus, 2002). Most mammalian species exhibit male-biased dispersal and female philopatry (Greenwood, 1980; Clutton-Brock, 1989; Prugnolle & de Meeus, 2002), but recent applications of genetic tools suggest wide variation in the direction, magnitude and timing of sex-biased dispersal (Handley & Perrin, 2007). Theoretical studies show that philopatry in concert with polygony may involve small scale genetic differentiation among social groups (Chesser, 1991b; Chesser, 1991a), which may have important evolutionary consequences for kin and localized selection (Coltman et al, 2003). In many ungulate species polygony and philopatry involves a pronounced fine-scale genetic structure (Mathews & Porter, 1993; Petit et al 1997; Purdue et al, 2000; Coltman et al, 2003; Nussey et al, 2005). Sex-biased dispersal at the subpopulation and meta-population levels has been poorly documented (Prugnolle & de Meeus, 2002), but has recently been reported for turtles (Bowen & Karl, 2007) and bats (Chen et al, 2008).
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