Evidence for hermaphroditism in the Squalius alburnoides allopolyploid fish complex.

Fish show an amazing variety of mechanisms of sex determination and modes of reproduction. Of these, simultaneous hermaphroditism has rarely been described. Here, we report a novel case of this phenomenon in adults of the Squalius alburnoides allopolyploid cyprinid complex. We found evidence for the simultaneous presence of mature male and female gonads on the basis of gonad gross morphology and histological analyses. Different stages of male and female germ cell maturation were identified, including motile spermatocytes. We hypothesize on the genetic and/or environmental causes of this phenomenon.

Divergence of larval morphology between Drosophila sechellia and its sibling species caused by cis-regulatory evolution of ovo/shaven-baby.

We report an extreme morphological difference between Drosophila sechellia and related species of the pattern of hairs on first-instar larvae. On the dorsum of most species, the posterior region of the anterior compartment of most segments is covered by a carpet of fine hairs. In D. sechellia, these hairs have been lost and replaced with naked cuticle. Genetic mapping experiments and interspecific complementation tests indicate that this difference is caused, in its entirety, by evolution at the ovo/shaven-baby locus. The pattern of expression of the ovo/shaven-baby transcript is correlated with this morphological change. The altered dorsal cuticle pattern is probably caused by evolution of the cis-regulatory region of ovo/shaven-baby in the D. sechellia lineage.