Question

A population of pigs lives on an island together with burrowing termites. Pigs that have the longest snouts tend to survive more frequently than those with shorter snouts. Over time, most of the pig population is made up of individuals that have very long snouts. This is an example of which type of selection?
directional selection
disruptive selection
stabilizing selection
ecosystem selection

Answer 1

Directional selection — because individuals at one extreme (very long snouts) have higher fitness, shifting the population mean toward that extreme.