Question

complete the following passage regarding adaptation.
when the environment ◌, organisms can be faced with new challenges to their survival and reproduction. for example, when terrestrial mammals invaded the ocean and evolved into whales, the evolution of ◌—an important adaptation—contributed to their successful integration into marine life. if traits that would enable an organism to better succeed already exist in some individuals of the population, ◌ is the means by which such traits become more common in the population. however, the population must experience ◌ to generate any novel variations that might enable the organisms to better succeed.

genetic drift, natural selection, is stable, mutation, gills, changes, gene flow, flippers

Explanation:

1. First blank: When the environment "changes", organisms face new survival/reproduction challenges (since a stable environment wouldn't bring new challenges).
2. Second blank: Terrestrial mammals evolving into whales would develop "flippers" (adaptation for marine life; gills are for fish, mammals don't have gills).
3. Third blank: "Natural selection" is the process where beneficial traits become more common in a population (as it favors traits that help survival/reproduction).
4. Fourth blank: "Mutation" is the source of novel genetic variations (needed for new traits to arise).

Answer:

1. changes
2. flippers
3. natural selection
4. mutation