Abstract
The analysis of polytene chromosomes in 26 strains of seven species in the Drosophila fasciola subgroup, from several locations in Brazil, in addition to strains of two species belonging to the Drosophila mulleri subgroup (D. aldrichi and D. mulleri), enabled us to determine that the 3c inversion found in the latter species differ in one of its break points from that present in the species of the fasciola subgroup. Therefore, a change in the mulleri complex denomination from inversion 3c to inversion 3u is proposed. Accordingly, the fasciola subgroup is no longer a lesser phylogenetic part within the mulleri subgroup. Rather, it is directly related to the likely ancestor of the repleta group, called Primitive I. This information removes the main obstacle to considering the Drosophila fasciola subgroup as an ancestral group within the Drosophila repleta species group, according to the hypothesis of Throckmorton. Our data also support the conclusion that D. onca and D. carolinae are closely related species based on one new inversion in chromosome 4 (4f2), in both species. D. fascioloides and D. ellisoni also form a pair of sister species based on the presence of fusions of chromosomes 2-4 and 3-5. D. rosinae is related only to the likely ancestor of the fasciola subgroup, where the 3c inversion was fixed.
Highlights
The repleta group of the genus Drosophila is endemic to the Americas
Fixed inversions on chromosome 4 were found in D. onca as well as in D. carolinae
What does not match previous findings is the fact that the 3c inversion found in fasciola does not have the same 3c breakpoints as described in the mulleri complex by Wasserman (1962a, b)
Summary
The repleta group of the genus Drosophila is endemic to the Americas. This group comprises more than 95 nominal species (Sturtevant, 1942; Vilela, 1983; Rafael and Arcos, 1989; Vilela and Bächli , 1990; Tidon-Sklorz and Sene, 1995a b, 2001; Bächli and Vilela, 2002), and is divided into six subgroups: fasciola, hydei, inca, mercatorum, mulleri and repleta.Their species are widely distributed in the New World and mostly found in semiarid regions with open vegetation (Pavan, 1959; Sene et al, 1980; Vilela, 1983; Vilela et al, 1983; Tidon-Sklorz and Sene, 1995c; Tidon-Sklorz et al, 1994). The repleta group of the genus Drosophila is endemic to the Americas This group comprises more than 95 nominal species (Sturtevant, 1942; Vilela, 1983; Rafael and Arcos, 1989; Vilela and Bächli , 1990; Tidon-Sklorz and Sene, 1995a b, 2001; Bächli and Vilela, 2002), and is divided into six subgroups: fasciola, hydei, inca, mercatorum, mulleri and repleta. The species in the hydei, mercatorum and repleta subgroups are mostly generalists, while those in the mulleri and inca subgroups use cacti as breeding sites (Pereira et al, 1983; Rafael and Arcos, 1989). The morphology of the testicles and of the seminal receptacle of the species in this subgroup is intermediate between that in the mulleri and repleta subgroups (Wasserman, 1962a)
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