Question

classify the statements as examples of directional selection, stabilizing selection, or disruptive selection.
directi nal selection stabilizing selection disruptive selection
answer bank
individuals of a bird species lay between 1 and 20 eggs. individuals of the bird species lay between 5 and 15 eggs after several generations
individuals of a bird species lay eggs of various brown colors in a depression on the ground.after several generations, the birds lay mostly dark brown eggs.
individual plants of a tree species have flowers that range from light pink to dark red. after several generations, most trees have flowers that are either light pink or dark red.

Explanation:

• Directional selection: Favors one extreme phenotype. In the second statement, birds shift to mostly dark - brown eggs (one extreme of the brown color range).
• Stabilizing selection: Favors the intermediate phenotype. In the first statement, the range of egg - laying (originally 1 - 20) narrows to 5 - 15 (intermediate values are favored).
• Disruptive selection: Favors two or more extreme phenotypes. In the third statement, flowers become either light pink or dark red (two extreme phenotypes are favored).

Answer:

• Directional selection: Individuals of a bird species lay eggs of various brown colors in a depression on the ground. After several generations, the birds lay mostly dark brown eggs.
• Stabilizing selection: Individuals of a bird species lay between 1 and 20 eggs. Individuals of the bird species lay between 5 and 15 eggs after several generations.
• Disruptive selection: Individual plants of a tree species have flowers that range from light pink to dark red. After several generations, most trees have flowers that are either light pink or dark red.