F-STATISTICS IN DROSOPHILA-BUZZATII - SELECTION, POPULATION-SIZE AND INBREEDING

Drosophila buzzatii is confined to reproducing in a well defined patch y environment consisting of rotting cactus cladodes which are ephemera l, permitting at most three generations. Flies emerging from such rots were used to estimate the additive genetic variance within rots and t he genetic variance between rots for body size and also were electroph oresed to determine their genotypes at six polymorphic loci. F statist ics were estimated from body size and allozyme data. The F(ST) derived from body size was significantly larger than the allozyme F(ST). It i s proposed this is due to selective differentiation of body size. The allozyme F(ST) is used to estimate effective population size: 10 < N < 50. It is suggested that the regularly observed positive F(IS)'s coul d be due to partial sib mating, S. If so, the estimated lower bound is S = 0.258. Experiments are identified which could support or contradi ct these interpretations.