Evolution of reproductive morphology among recently diverged taxa in the Drosophila mojavensis species cluster

• Published in: Ecology and evolution 2012-02, Vol.2 (2), p.397-408
• Main Authors: Richmond, Maxi Polihronakis, Johnson, Sarah, Markow, Therese A.
• Format: Article
• Language: English
• Subjects: Aedeagus; Animal reproduction; Cactus; Clusters; Copulation; Divergence; Drosophila arizonae; Drosophila mojavensis; Evolution; Fruit flies; Genitalia; Hypotheses; Insects; Laboratories; Males; Mate recognition; morphological evolution; Morphology; morphometrics; Original Research; Phylogenetics; Reproductive isolation; Shape recognition; Sibling species; Sonoran Desert; Speciation; Variance analysis; Variation
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.93

The morphological evolution of sexual traits informs studies of speciation due to the potential role of these characters in reproductive isolation. In the current study, we quantified and compared genitalic variation within the Drosophila mojavensis species cluster to infer the mode of evolution of the male aedeagus. This system is ideal for such studies due to the opportunity to test and compare levels of variation along a divergence continuum at various taxonomic levels within the group. Shape variation was quantified using elliptic Fourier descriptors and compared among the four D. mojavensis host races, and between D. mojavensis and its sister species Drosophila arizonae. Aedeagus shape was diagnostic for D. arizonae, and among three of the four D. mojavensis subspecies. In each of these cases, there was less variation within subspecies than among subspecies, which is consistent with the pattern predicted if genitalia are evolving according to a punctuated change model, and are involved with mate recognition. However, aedeagus shape in Drosophila mojavensis sonorensis was highly variable and broadly overlapping with the other three subspecies, suggesting aedeagus evolution in this subspecies is more complex and subject to additional evolutionary factors. These results are interpreted and discussed in the context of selection on mate recognition systems and the potential for failed copulation. The current study investigates the mode of aedeagus shape evolution among four subspecies of the cactophilic fly, Drosophila mojavensis. Our results indicate that aedeagus shape is diagnostic; however, evolution of aedeagus shape is not the same for each subspecies.