Question

in a bird population, 50% of the individuals had white feathers, and 50% had colored feathers. over time, it was observed that 98% of the population had colorful feathers. the rest had white feathers. how did the type of selection in this example affect the populations biodiversity?
directional selection did not increase the populations biodiversity.
stabilizing selection increased the populations biodiversity.
disruptive selection decreased the populations biodiversity.
ecosystem selection did not increase the populations biodiversity

Explanation:

• Directional selection: Favors one extreme phenotype. Here, initially there was an equal split (50 - 50) between white and colored feathers, and then 98% had white feathers. This is a shift towards one extreme (white feathers). Since it moves the population towards one phenotype, it does not increase biodiversity (which is about having a variety of traits).
• Stabilizing selection: Favors the intermediate phenotype. There is no mention of an intermediate - no such mechanism is described here.
• Disruptive selection: Favors extreme phenotypes. But the example shows a shift to one extreme (white feathers), not maintaining or increasing two extremes.
• Ecosystem selection is not a standard form of natural selection in evolutionary biology (the main forms are directional, stabilizing, and disruptive).

Answer:

A. Directional selection did not increase the population’s biodiversity.