PARTHENOGENESIS IN THE TROPICAL GEKKONID LIZARD,NACTUS ARNOUXII (SAURIA: GEKKONIDAE)

As currently diagnosed, Nactus arnouxii includes unisexual and bisexual populations. The geographic distribution of each type was estimated by sex-ratio analysis of samples from southwestern Pacific islands. Males were absent from southern Vanuatu (excluding Aneityum), New Caledonia, and all islands to the east that have been sampled. Both types of populations appear to be present on Aneityum. Chromosome and protein analyses showed that the bisexual populations are highly polytypic and probably consist of more than one biological species. The unisexual N. arnouxii were diploid, highly heterozygous, and showed no genetic segregation. The absence of segregation suggests clonal reproduction, substantiating parthenogenesis. The high heterozygosity of the unisexuals indicates their origin through hybridization. One parent was genetically similar to the extant bisexual population from northern Vanuatu. The other parent has not been identified, but its genetic characteristics are predicted by phylogenetic analysis.