The Elements of Evolution (41-8) Vinegar Flies

 Vinegar Flies

Adaptation to different environments may lead to reproductive isolation. ~ American evolutionary biologist Henry Chung et al

The vinegar fly Drosophila serrata speciated from Drosophila birchii via epigenetic regulation of a single gene that affects both mating preference and desiccation resistance.

Cuticular hydrocarbons (CHCs) have various functions in insects, including communication. One class of CHC – methyl-branched CHC (mbCHC) – protects an insect from desiccation by sealing its cuticle.

D. birchii is a niche specialist that lives in the rainforests of Australia and Melanesia. Owing to a low mbCHC level, D. birchii is extremely sensitive to dryness.

In contrast, the generalist D. serrata is found on the fringes of the rainforest on the east coast of Australia. It is relatively desiccation-resistant, thanks to generous manufacture of mbCHCs.

The 2 vinegar flies do not interbreed. mbCHC level is a factor in mating success for male D. serrata, as females won’t mate with a fly that has low mbCHC.

The gene that controls mbCHC production is regulated by RNA interference (RNAi), which mediates mbCHC level. By contributing to both mating success and desiccation resistance, mbCHC level constitutes a dual trait.