A MOLECULAR APPROACH TO THE STUDY OF GENIC HETEROZYGOSITY IN NATURAL POPULATIONS IV. PATTERNS OF GENIC VARIATION IN CENTRAL, MARGINAL AND ISOLATED POPULATIONS OF <i>DROSOPHILA PSEUDOOBSCURA</i>

Abstract

CCORDING to the synthetic theory of evolution, populations of a species A diverge in their gene pool as a result of differential selection of genetic variation in these populations and as a result of random genetic drift. The kind and magnitude of genetic divergence between populations is governed mainly by interaction of population size, migration rate and selection intensity. In order then to understand evolutionary phenomena in natural populations, one has to start by determining the pattern of genetic variation in populations which come from different ecogeographic regions of the species range and represent different degrees of isolation from the other populations of the species. By using acrylamide gel electrophoresis we have shown that or a random sample of loci, a great deal of genic variation exists in Drosophila pseudoobscura More recently we have demonstrated selection of different alleles of the Pt-IO and Amy loci in different gene arrangements of D. pseudoobscura and D. persimilis (PRAKASH and LEWONTIN 1968). This