Peppered moths

The peppered moth is one of the most famous animals in evolutionary biology. Victorian collections show how a melanic version of this normally speckled species spread through sooty urban areas because its black wings camouflaged resting moths from hungry birds (see picture above). The exact genetic change involved, however, remained elusive. But, in a paper in Nature, Arjen van’t Hof of Liverpool University, in England, and his colleagues, say they have nailed it down. It is a transposable element—a piece of DNA that leaps from place to place in the genome. In this case it has leapt into a gene called cortex, which controls cell division. That promotes cortex’s expression. Just why this makes wings black, though, has yet to be worked out.

Source: Economist