Question

Explain three kinds of evolutionary responses as a result of natural selection on quantitative traits.

Answer 1

1. Stabilising selection: Favours intermediate phenotypes and eliminates both extremes; variation decreases while the mean usually remains similar.
2. Directional selection: Favours one extreme and selects against the other, shifting the population mean towards the favoured extreme.
3. Disruptive selection: Favours both extremes and selects against intermediate phenotypes, producing two peaks in the distribution.