Does evolution reduce the body size? A study of the four members of newly evolved nasuta-albomicans complex of Drosophila

Our long range interracial hybridization experiments between a pair of cros s fertile races, Drosophila nasuta (2n = 8) and D. albomicans (2n = 6) have resulted in the evolution of two new karyotypic strains under laboratory c onditions, which are named as Cytorace 1 and Cytorace 2. These Cytoraces ha rbor chromosomes from both parents. Here, we compare the body size of the p arental races and newly evolved Cytoraces and the relationship between the body size and fitness. Analysis reveals that the parental races have reduce d fertility and are larger in body size than newly evolved Cytoraces. Thus, the newly evolved Cytoraces show reduced body size and better fitness in t he course of their evolution.