Genetic Detection of Sex-Biased and Age-Biased Dispersal in a Population of Wild Carnivore, the Red Fox, Vulpes vulpes

Field studies conducted on rural red fox (Vulpes vulpes) populations suggest that the majority of males tend to disperse while the majority of females tend to be philopatric, that males disperse farther than females, and that most of the foxes disperse during their first year of life. However, the quantification of dispersal parameters is poorly documented in the red fox, because this carnivore is notoriously difficult to follow from birth to maturity. The aim of this study was to test hypotheses from field data with the help of a molecular analysis using six random amplified polymorphic DNA (RAPD) markers. The study was conducted on samples collected from 85 foxes in a French rural population. Genetic and geographical distances between pairs of Individuals were calculated for the 3570 potential pairs originating from this population to determine whether the foxes had dispersed. High genetic diversity and an absence of genetic clusters among studied individuals support the occurrence of intense and constant gene flow in the study population, probably induced by dispersion. At least 16.2% of the potential pairs we studied were subject to dispersal. Sex-biased dispersion was not observed, apart from a sex bias in favor of females towards long-distance dispersal. A predominance of males that ultimately dispersed a long distance could not thus be confirmed. Furthermore, it seems that dispersal did not occur primarily in the subadult age class In our rural study area, but that some pairs of juveniles may also have been Involved in dispersal.