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 population’s biodiversity?
directional selection did not increase the population’s biodiversity.
stabilizing selection increased the population’s biodiversity.
disruptive selection decreased the population’s biodiversity.
ecosystem selection did not increase the population’s biodiversity.

Explanation:

1. First, recall types of natural selection:

• Directional selection: Favors one extreme phenotype, shifting the population’s trait distribution. Here, the frequency of colored feathers (one phenotype) increased from 50% to 98%, while white feathers (the other) decreased. This is directional selection.
• Stabilizing selection: Favors intermediate phenotypes, reducing variation (wouldn't increase biodiversity, so the second option is wrong).
• Disruptive selection: Favors two extreme phenotypes, increasing variation (but here one phenotype dominated, so third option is wrong).
• Ecosystem selection isn't a standard type of natural selection affecting phenotypic frequencies like this, so the fourth option is incorrect.
• Directional selection in this case reduced the proportion of white - feathered birds, so it didn't increase biodiversity (since one phenotype became dominant, reducing the variety in feather color phenotypes).

Answer:

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