This is a surprisingly high proportion, since the scans often miss various genes that are known for other reasons to be under selection.

For example, you would expect to find that a mutation which causes prenatal death or severe disease to be under selection.

Under natural selection, a gene which improves the fitness of individuals will increase in frequency.

Then again, others do not consider them feral any more but completely wild, since they have been living under natural selection for a very long time.

Genes may be under strong selection in response to local diseases.

This means that most of the changes are functional in nature, and therefore are under selection.

Displacement proceeds by competition under natural selection, and the better-adapted species win.

It performs well even on coding sequences that include sites believed to be under selection.

This is because sexual ornaments are under intense directional selection.

The genes were probably under natural selection in the people who became the island's first inhabitants.