Darwin's finches, which inhabit the Galapagos Islands, originally migrated from mainland South America. The loss of plants producing medium-sized nuts on one island led to the evolution of finches with either small or large beaks and selected against finches with medium-sized beaks. What kind of selective pressure is in action here?

Question

directional selection

genetic drift

gene flow

disruptive selection

Answer 1

The kind of selective pressure in action here is disruptive selection. This is because the population is being divided into two distinct groups (finches with small beaks and finches with large beaks) due to the loss of plants producing medium-sized nuts. The individuals with medium-sized beaks are being selected against, which creates a disruptive pattern of selection.