Chromosomal Studies of the New Zealand Herpetofauna

Abstract

The four topics presented in the thesis are taxonomically distinct so each has been accorded a separate abstract. New Zealand Skinks The karyotypes for two New Zealand skinks are presented for the first time, namely Oligosoma nigriplantare nigriplantare and Oligosoma microlepis. The results of the current study are then discussed in context with previous research by Hardy (1979) and O'Malley (1971). It is suggested that the New Zealand Oligosoma skink fauna has a shared karyotype with Leiolopisma telfairi (Round Is., Mauritius), and differs considerably from the Australian skinks. Cyclodina, the other genus present in New Zealand appears to be a subsequent speciation from Oligosoma. New Zealand Geckos Karyotypes of four New Zealand gecko species are presented (three for the first time). These species represent the two gecko genera present in New Zealand namely Hoplodactylus and Naultinus. The New Zealand gecko karyotype appears to vary in the number of pericentric inversions. Comparison is made to the theories on gecko evolution of King (1987) and Bauer (1990) and both are essentially rejected. It is suggested that the New Zealand gecko fauna is much older than originally thought and has no close karyotypic relatives within the Australasian gecko fauna. The sex chromosomes of the endemic frog Leiopelma hochstetteri This essay explores the cytogenetics of the New Zealand endemic frog Leiopelma hochstetteri. Research by Professor D.M. Green (McGill University, Canada) has suggested a novel sex determination system, where the W sex chromosome is on a supernumerary (or B) chromosome. This essay reassesses Green's research and suggests a more parsimonious conclusion, namely that the sex chromosomes have yet to be found. Chromosomal examination of the tuatara A non-sacrificial blood culture technique was developed to obtain chromosome spreads of the tuatara, an endemic New Zealand reptile. Chromosomes were examined from both species namely Sphenodon guntheri, and Sphenodon punctatus. A potential species difference in the NOR carrying chromosome was seen, a possible fragile site or primitive sex chromosome has been identified, and a morphologically different chromosome in one animal was noted. Nucleolous banding regions and some C bands have been demonstrated, although G bands have yet to be obtained.