Evolution of male genitalia in the Drosophila repleta species group (Diptera: Drosophilidae)

The Drosophila repleta group comprises more than one hundred species that inhabit several environments in the Neotropics and use different hosts as rearing and feeding resources. Rather homogeneous in their external morphology, they are generally distinguished by the male genitalia, seemingly their fastest evolving morphological trait, constituting an excellent model to study patterns of genital evolution in the context of a continental adaptive radiation. Although much is known about the evolution of animal genitalia at population level, surveys on macroevolutionary scale of this phenomenon are scarce. This study used a suite of phylogenetic comparative methods to elucidate the macroevolutionary patterns of genital evolution through deep time and large continental scales. Our results indicate that male genital size and some aspects of shape have been evolving by speciational evolution, probably due to the microevolutionary processes involved in species mate recognition. In contrast, several features of the aedeagus shape seemed to have evolved in a gradual fashion, with heterogeneous evolutionary phenotypic rates among clades. In general, the tempo of the evolution of aedeagus morphology was constant from the origin of the group until the Pliocene, when it accelerated in some clades that diversified mainly in this period. The incidence of novel ecological conditions in the tempo of aedeagus evolution and the relationship between species mate recognition and speciation in the Drosophila repleta group are discussed. The phylogeny of Drosophila repleta group placed at the left of image shows the sites where significant shifts occurred in the rates of phenotypic evolution of aedeagus, the species used in this work and their aedeagus. At the centre of image, the mode of evolution is shown by colouring the axes of variation of different traits of the aedeagus (i.e., green for gradual change and magenta for speciational change). The portion quantified in this work was he intromittent portion of aedeagus and correspond to sharp area (the blurred area is the no‐intromittent portion of aedeagus). The aedeagus shows as example is of Drosophila serido. At right of the image is shown the tempo of evolutionary change of aedeagus in Drosophila repleta species group and in both subgroups that showed significant increases in their evolutionary rates.