PATTERNS OF DIFFERENTIATION AMONG WILD RABBIT-POPULATIONS ORYCTOLAGUS-CUNICULUS L IN ARID AND SEMIARID ECOSYSTEMS OF NORTH-EASTERN AUSTRALIA

Feral rabbit populations in Australia have generally been managed usin g localized control procedures. While these procedures may result in l ocal extinctions, persistence of populations will depend on the probab ility of recolonization. Genetic markers developed using temperature g radient gel electrophoresis (TGGE) combined with heteroduplex analysis (HA) of mitochondrial DNA (mtDNA) were used to characterize the degre e of subdivision and extent of gene flow within and among rabbit popul ations distributed over large distances (up to 1000 km) in southern Qu eensland (QLD) and north-west New South Wales (NSW), Australia. TGGE a nalyses revealed significant heterogeneity in mtDNA control region hap lotype frequencies. From heterogeneity chi(2) tests, it was evident th at the differentiation observed was largely attributable to five sites which were located in the semiarid eastern region, whereas haplotype frequencies were homogeneous throughout the arid western region. These results suggest that there are independent population systems within the study area. The extent of gene flow among local populations within each system is related to the spatial configuration of acceptable hab itat patches and the persistence of the populations is determined by t he probability of recolonization following local extinction. These dat a suggest that to provide better overall control of rabbit populations , different management strategies may be necessary in arid and semiari d ecosystems. In arid south-west QLD and north-west NSW, where extensi ve gene flow occurs over large distances, rabbit populations should be managed at a regional level. In semiarid eastern QLD, where gene flow is restricted and populations are more isolated, localized control pr ocedures may provide effective short-term relief. These results indica te that in nonequilibrium systems with patchy distribution of individu als, the interpretation of migration rate from estimates of gene flow obtained using existing genetic models must include an understanding o f the spatial and temporal scales over which population processes oper ate.