1. Chromosomal polymorphism in two populations of D. subobscura from Barcelona has been analysed and compared with the polymorphism which has been reported from other populations.2. In spite of microclimatic differences between the Barcelona sites, there is no evidence of differences in the frequency of inversion types nor of seasonal differences within one of these sites.3. Regularities in the array of frequencies of chromosomal types in Barcelona and other populations suggest that the polymorphism is mainly adaptive although there is also evidence of differences due to distance which are not obviously associated with differences in habitat.4. In general the index of free recombination gives higher values in the marginal populations of D. subobscura, but further data are needed to arrive at a definite conclusion on this point since the present evidence is rather ambiguous.
TEMPORAL CHANGES IN CHROMOSOMAL POLYMORPHISM OFDROSOPHILA SUBOBSCURARELATED TO CLIMATIC CHANGES
