Racial divergence in the foreleg bristles of four members of the nasuta–albomicans complex of Drosophila

Abstract

Drosophila nasuta nasuta and D. n. albomicans are a pair of sibling allopatric chromosomal races of nasuta subgroup of Drosophila, and have resulted in the evolution of two new karyotypic strains called Cytorace 1 and Cytorace 2. These two races are considered to be the members of the newly evolved nasuta–albomicans complex of Drosophila, which are allo-sympatric populations useful for understanding the early events of raciation under laboratory conditions. These newly developed Cytoraces have shown appreciable divergence in foreleg bristle number, displaying increased foreleg bristle number with reduced foreleg length, in comparison to D. n. nasuta and D. n. albomicans, which suggests a negative correlation between foreleg bristle number and foreleg length. This racial divergence could be due to the transgressive segregation of genes responsible for foreleg bristle number during the evolution of these Cytoraces.