Question

match the items.
a. the environment changes and organisms on both extremes adapted to new environments while the organism that were common could not adapt to the new environment.
b. the environment has not changed in several years and the species is becoming more adapted to this environment.
c. environment changed and the population adapted and shifted to a new common phenotype.

1. stabilizing selection
2. disruptive selection
3. directional selection

Explanation:

• Stabilizing selection occurs when the environment is stable. Organisms that are well - adapted to the existing environment (the common phenotype) are favored. So, when the environment has not changed in several years and the species is becoming more adapted to this environment (item b), it is stabilizing selection.
• Disruptive selection happens when extreme phenotypes are favored over the intermediate phenotype. In this case, when the environment changes and organisms on both extremes adapted to new environments while the common organism could not (item a), it is disruptive selection.
• Directional selection is when the environment changes and the population shifts towards a new phenotype. When the environment changed and the population adapted and shifted to a new common phenotype (item c), it is directional selection.

Answer:

1. Stabilizing selection - b
2. Disruptive selection - a
3. Directional selection - c