Hot clock key to fruit fly’s global spread

Sometimes, survival of the fittest means dependence on weak links.

Widely distributed fruit fly species have a temperature-sensitive step in the manufacture of a key part in their biological clocks. The heat-sensitive stumbling block may be the reason Drosophila melanogaster and Drosophila simulans have been able to spread to temperate zones while their cousins haven’t, a new study in the Dec.