Parentage analysis in a managed free ranging population of southern white rhinoceros : genetic diversity, pedigrees and management

Abstract

Small populations are vulnerable to the consequences of breeding within closed groups as the loss of genetic variability can lead to inbreeding depression. Here, we use microsatellite genotypes to assess variability and parentage within a small, managed population of southern white rhinoceros in northern Namibia. Tissue samples gathered from either a modified biopsy darting technique or ear notches allowed us to obtain genotypic data for all individuals in the population. As expected for this species, genetic variability in the population was relatively low (overall H obs 0.45). In combination with detailed management records for the period 1993–2009, we were able to assign both parents for all 23 offspring. Only one calf of seven in the F2 generation arose from father–daughter inbreeding within the population. Our analysis revealed that paternity was initially dominated by a single founder bull siring 10 of 13 calves over 9 years; paradoxically, the other founder bull was selected for removal based on observations suggesting he was behaviourally dominant and therefore the likely sire of most calves. We also found that young introduced bulls were breeding successfully within 6 months of their arrival, well before having established their home ranges. We argue that in order to optimally manage and conserve the southern African white rhinoceros meta-population it is essential to have accurate pedigree information and genetic data for all individuals in the numerous small populations that are key to the survival of the species.