NUCLEOTIDE POLYMORPHISM AT THE RP49 REGION OF DROSOPHILA-SUBOBSCURA -LACK OF GEOGRAPHIC SUBDIVISION WITHIN CHROMOSOMAL ARRANGEMENTS IN EUROPE

Restriction-site polymorphism at the rp49 gene region has been studied in 234 lines of Drosophila subobscura representing different gene arr angements for the O chromosome. The population surveyed (El Pedroso, S pain) was sampled four times in each of two consecutive years. The dat a indicate that the two chromosomal classes studied, O-[ST] and O-[3+4 ], are genetically differentiated in El Pedroso. Comparison of the pre sent results with those previously obtained for two other populations further supports that, for a given chromosomal class, European populat ions are not genetically differentiated. This lack of differentiation at the rp49 region within O-[ST] and within O-[3+4] stands in contrast to the clear latitudinal clines found in Europe for these arrangement s.