RELATEDNESS STRUCTURE DETECTED BY MICROSATELLITE ANALYSIS AND ATTEMPTED PEDIGREE RECONSTRUCTION IN AN ENDANGERED MARSUPIAL, THE NORTHERN HAIRY-NOSED WOMBAT LASIORHINUS-KREFFTII

The northern hairy-nosed (NHN) wombat is perhaps Australia's most enda ngered mammal. Being fossorial and nocturnal as well as rare, NHN womb ats are difficult to observe in the wild. Hence little is known of the ir social biology, such as their mating and dispersal systems. A hypot hesis has been advanced that adult females of the species disperse pos t-breeding, leaving their young to inhabit the natal burrow. Female-bi ased dispersal is expected to result in higher relatedness amongst mal es in a burrow cluster than amongst females in a burrow cluster. The u sefulness of a panel of microsatellite markers in estimating the relat edness structure, and in reconstructing pedigrees for, the sole known population of NHN wombats was assessed. Microsatellite genotypes at ei ght or nine loci were obtained from 58 of the 85 known individuals, an d used to estimate pairwise individual relatedness using Queller & Goo dnight's (1989) RELATEDNESS 4.2. Our analysis gave the unexpected resu lt that both males and females were significantly more closely related to their same-sex burrow cluster mates than random, while opposite-se x animals sharing burrows were only slightly (nonsignificantly) more r elated than random. This raises the possibility of dispersal patterns which lead to association of same-sex relatives. The observed relatedn ess structure is not expected to make likely a high incidence of inbre d matings, as close relatives of the opposite sex are not significantl y associated in space. Parentage analysis was attempted using genetic exclusion and LOD likelihood ratios, but proved difficult because of l ow genetic variation, incomplete sampling of potential parents, and pa ucity of ecological data such as known mother/offspring pairs and ages of individuals.