Relatedness and avoidance of inbreeding in the lizard, Tiliqua rugosa

Two potential mechanisms for reducing the level of inbreeding, sex-biased d ispersal and kin avoidance, were examined in the Australian sleepy lizard, Tiliqua rugosa. The home range centres, and the genotypes at four polymorph ic microsatellite DNA loci were determined for adult lizards in a 70-ha stu dy area near Mount Mary, South Australia. From estimates of genetic related ness, females were as closely related to other females as they were to male s, both within the whole study area, and within home ranges. Similarly, mal es were as closely related to other males as they were to females. This sug gests that dispersal in the population is not sex-biased. Sleepy lizards fo rm monogamous pairs during the spring. Partners were less closely related t o each other than to other potential partners in the home range area. This suggests active choice of unrelated partners. The mechanism for recognising related from unrelated individuals is unknown, but the behaviour could red uce inbreeding.