TRANSFER OF GENETIC INFORMATION IN THE RP49 REGION OF DROSOPHILA-SUBOBSCURA BETWEEN DIFFERENT CHROMOSOMAL GENE ARRANGEMENTS

Nucleotide variation in the region including the ribosomal protein 49 (rp49) gene was investigated by direct sequencing of 10 alleles of Dro sophila subobscura from chromosomes differing in gene arrangement. Fif ty-six nucleotide and seven length polymorphisms were detected over a 1.5-kb region. Of the 20 nucleotide polymorphisms present more than on ce in the sample, 13 were segregating in O[3+4], 9 in O[3+4+8], and 4 in O[st] chromosomal classes. Several of these polymorphisms were segr egating in more than one chromosomal class, a strong indication of gen etic transfer between different chromosomal gene arrangements either b y double crossover or gene conversion. Given the probable role played by gene conversion in the history of the rp49 region in D. subobscura, estimates of nucleotide diversity within chromosomal class indicate t hat the O[3+4] chromosomal gene arrangement is older than the O[st] ar rangement.