Abstract
BackgroundThe rapid evolution of genital morphology is a fascinating feature that accompanies many speciation events. However, the underlying patterns and explanatory processes remain to be settled. In this work we investigate the patterns of intraspecific variation and interspecific divergence in male genitalic morphology (size and shape) in the cactophilic sibling species Drosophila buzzatii and D. koepferae. Genital morphology in interspecific hybrids was examined and compared to the corresponding parental lines.ResultsDespite of being siblings, D. buzzatii and D. koepferae showed contrasting patterns of genital morphological variation. Though genitalic size and shape variation have a significant genetic component in both species, shape varied across host cacti only in D. buzzatii. Such plastic expression of genital shape is the first evidence of the effect of rearing substrate on genitalic morphology in Drosophila. Hybrid genital morphology was not intermediate between parental species and the morphological resemblance to parental strains was cross-dependent.ConclusionOur results suggest the evolution of different developmental networks after interspecific divergence and the existence of a complex genetic architecture, involving genetic factors with major effects affecting genital morphology.
Highlights
The rapid evolution of genital morphology is a fascinating feature that accompanies many speciation events
A total of 606 males were analyzed in this study (252 D. buzzatii, 294 D. koepferae and 60 interspecific hybrids)
The total number of principal components explaining a significant proportion of shape variation was 13 in D. koepferae and 12 in D buzzatii
Summary
The rapid evolution of genital morphology is a fascinating feature that accompanies many speciation events. Notwithstanding the taxonomic importance of genitalic morphology, intraspecific studies addressing the causes and consequences of intraspecific morphological variation are scarce Such studies, using methods successfully applied in evolutionary biology, offer the opportunity to gain new insights into the evolutionary processes and forces involved in genitalic evolution [3]. The lock and key hypothesis [8] states that male genitalia evolve as a species-specific trait in order to properly fit in female genitalic organs. This theory predicts a canalized development of male genitalia and low levels of phenotypic and genotypic variation, since genitalic traits are expected to be under strong stabilizing selection [3,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
