Question

An example of positive directional selection is?

1) cystic fibrosis
2) sympatric populations of hummingbirds with both long and short beaks
3) beak sizes in the thirteen Galapagos finches
4) intrasexual selection

Answer 1

Positive directional selection is exemplified by the darker coloration of the peppered moth in response to the environmental changes brought by the Industrial Revolution, leading to better camouflage and increased survival. The correct option is 3) beak sizes in the thirteen Galapagos finches

Step-by-step explanation:

An example of positive directional selection is the evolution of the peppered moth during the Industrial Revolution in England. Due to the increase in pollution, which darkened the trees with soot, the previously light-colored moths were easier for predators to see. This environmental change was selected for the darker coloration in moths, which blended better with the sooty environment, leading to an increase in the frequency of the melanic form of the moth.

Directional selection can lead to evolutionary changes in a population by consistently favoring individuals with phenotypes at one end of the spectrum. This type of selection results in a shift of the population's genetic variance toward a new, advantageous phenotype. In contrast to other types such as stabilizing selection or disruptive selection, directional selection moves the population toward one extreme phenotype. The correct option is 3) beak sizes in the thirteen Galapagos finches