GENETIC-VARIABILITY IN THE WINGLESS SUB-ANTARCTIC GENUS ANATALANTA (DIPTERA, SPHAEROCERIDAE) - A PRELIMINARY APPROACH

The first study on the genetic variability of a wingless subantarctic fly (Diptera: Sphaeroceridae) at Iles Crozet is presented. Flies of th e genus Anatalanta live mainly in seabird colonies from the littoral l evel to 700 m a.s.l. Two species are known: A. aptera Eaten and A. cro zetensis Enderlein. Several morphological forms from 2 islands have be en surveyed and 21 enzyme systems, involving 30 common putative enzyme loci, were scored from reared individuals. Mean heterozygosity values vary from 0.053 to 0.169. Genetic differentiation is weak with low Ne i's distances. Noticeable gaps between morphological and genetic data are emphasized and question the real taxonomic status of the two recog nized species. It is now necessary to compare populations of the genus Anatalanta from its whole distributional range (Iles Crozet, Iles Ker guelen and Heard Island). An improved understanding of the historical processes by which these islands were colonized could result from thes e studies.