Estimation of population fitness of parental races Drosophila nasuta nasuta and Drosophila nasuta albomicana and of the newly evolved Cytoraces I and II

Abstract

Interracial hybridization between Drosophila nasuta nasuta (2n = 8) and Drosophila nasuta albomicana (2n = 6) has resulted in the emergence of new karyotypic strains called Cytorace I (♀ 2n = 7; ♂ 2n = 6) and Cytorace II (♀ and ♂ 2n = 6). The parental and the newly evolved Cytoraces were assessed for parameters of fitness, i.e., fecundity, egg to adult rate of development, egg to adult viability, and adaptedness. The newly evolved Cytoraces not only differ from each other but also differ from their parental races in their fitness phenotypes. Each one of these four strains represent features of different genetic systems with different adaptive phenotypes.Key words: Drosophila, interracial hybridization, population fitness.