Between species divergence of cyst length distributions in the Drosophila melanogaster species complex

Abstract

The cyst lengths in each of the four cryptic species of the Drosophila melanogaster complex are stable. There is no variability due to the geographic origin of lines or strains. There is strong evidence that the distribution of cyst length is a highly species-specific trait. The extent to which the cyst length distributions of the four species diverge, is striking; two species (D. mauritiana and D. simulans) have short cysts while the others (D. sechellia and D. melanogaster) have long cysts. There is partial overlap within but not between these long and short distributions. In D. mauritiana and D. simulans where the overlap is the greatest the variability is the least. Although D. mauritiana, D. simulans and D. sechellia make a mono-phyletic group with respect to D. melanogaster, D. sechellia appears to have strongly diverged from the mauritiana-simulans pair. The cyst length of an hypothetical common ancestor can not be inferred from these studies. © 1987, The Genetics Society of Japan. All rights reserved.