Host-dependent phenotypic plasticity of male genital morphology in cactophilic sibling Drosophila of the repleta group (Diptera, Drosophilidae)

SOTO, IM, MH MANFRIN & E. HASSON

JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH

Blackwell

Año: 2008 vol. 46 p. 368 - 373

0947-5745

The rapid evolution of male genital morphology is a characteristic feature of several animal groups. Such rapid divergence makes this trait a useful key for species identification. The aedeagus, the intromittent organ of male genitalia, is considered the main diagnostic trait in the Drosophila repleta group. In this study we analysed phenotypic plasticity and genetic variations associated with aedeagus size and shape in the cactophilic sibling species Drosophila gouveai Tidon-Sklorz and Sene, 2001 and Drosophila antonietae Tidon-Sklorz and Sene, 2001. Phenotypic plasticity in aedeagus morphology was evaluated in terms of the response to rearing media prepared with each species natural host plant, Pilosocereus machrisii Dawson, 1957 and Cereus hildmannianus Schum, 1890 respectively. Our results show that aedeagal shape differed significantly between species and that both shape and size presented host-related phenotypic plasticity in both species. Flies reared on P. machrisiihad, on average, larger aedeagi than those grown in C. hildmannianus. The general shape of aedeagus also differed significantly between flies thatemerged in different host cactus. Patterns of variation in aedeagus morphology are discussed in the light of the current knowledge of evolutionary relationships and host plant use, in the D. buzzatii cluster, an assemblage of species in active cladogenesis.