Molecular zyxwvutsrqpon Ecology zyxwvutsr (1995) 4,239-247 Natal dispersal and genetic structure in a population of the European wild rabbit zyxw (Oyctolagus cuniculus), N. J. WEBB, zyxwvuts K.M. IBRAHIM, D. J. BELL and G. M.HEWITT School of Biological Sciences, University zyxwvuts of East Anglia, Norwich, Norfolk NR4 nJ, UK Abstract A combination of behavioural observation, DNA fingerprinting, and allozyme analysis were used to examine natal dispersal in a wild rabbit population. Rabbits lived in territorial, warren based social groups. Over a &year period, significantly more male than female rabbits moved to a new social group before the start of their first breeding .season. This pattern of female philopatry and male dispersal was reflected in the genetic structure of the population. DNA fingerprint band-sharing coefficients were signifi- cantly higher for females within the same group than for females between groups, while this was not the case for males. Wright's inbreeding coefficients were calculated from fingerprint band-sharing values and compared to those obtained from allozyme data. There was little correlation between the relative magnitudes of the F-statistics calculated using the two techniques for comparisons between different social groups. In contrast, zy two alternative methods for calculating FsT from DNA fingerprints gave reasonably concordant values although those based on band-sharing were consistently lower than those calculated by an 'allele' frequency approach. A negative FE value was obtained from allozyme data. Such excess heterozygosity within social groups is expected even under random mating given the social structure and sex-biased dispersal but it is argued that the possibility of behavioural avoidance of inbreeding should not be discounted in this species. Estimates of genetic differentiation obtained from allozyme and DNA fingerprint data agreed closely with reported estimates for the yellow-bellied marmot, a species with a very similar social structure to the European rabbit. Keywords: allozymes, DNA fingerprinting, F statistics, natal dispersal, Oyctolugus cuniculus Received 22 April 1994; revision received 19 September 1994; accepted 17 zyxwv October 1994 In trod uc tion The form and level of dispersal zyxwvuts can play an important role in determining the genetic structure of natural popula- tions (McGacken zyxwvutsrq & Bradbury 1977; Slatkin 1987). In many mammals, males show a greater tendency for movement between their birthplace and first breeding lo- cation (natal d i s p e d ) than females, while in birds the cOnverSe is generally true (Greenwood 1980). This sex-bi- ased, natal dispersal might therefore be reflected in differ- ing degrees of genetic relatedness among males and fe males of a species. Relatednessamong the philopatric sex within a localized area will on average be higher than among the dispersing sex, provided that members of the latter show no tendency to move with relatives. The ge- Cofiespondence: D. J. Bell. Fax +44 1603 592250. netic effects of such sex-biased dispersal should be more marked in species with stable breeding groups. The European wild rabbit is an excellent subject in which to investigate social and genetic structure since its body size permits both behavioural observation and easy handling for tagging and sampling. The species forms stable, territorial groups, typically of one to three adult males and one to six adult females. Within these groups there are separate linear dominance hierarchies among males and females (for a review see Bell 1983). Previous studies have demonstrated sex-biased natal dispersal, with more males than females transferring to a new social group before their first breeding season (Dunsmore 1974; Parer 1982; Cowan 1983). In the present study we used DNA fingerprinting and allozymes to investigate relatedness among adult male and female rabbits at an intrapopulational level.