GENETICS AND LINKAGE MAPPING OF DROSOPHILA-BUZZATII

Of 51 visible mutants isolated from natural or laboratory populations of Drosophila buzzatii, or X-ray induced, 42 have been assigned to chr omosomes, and linkage maps have been constructed. About half of the au tosomal mutants map to chromosome 2, with only two on chromosome 3 and none on chromosome 4. For the whole repleta group, chromosome 2 also exhibits much greater inversion variability than other chromosomes, wh ich suggests variation among chromosomes in apparent mutability. The c hromosomes of D. buzzatii are homologized to those of D. melanogaster and to the standard chromosomal elements of Drosophila. Sequence compa risons for six X chromosome mutant genes, whose homology is reasonably certain, in 13 Drosophila species confirm linkage group conservation but great variation among species in gene order. The linkage group con servation of single-copy genes stands in contrast to observed transpos itions between elements for tandem repeat genes.