Why might trait divergence differ between lakes that experience similar selective pressures?

Why might trait divergence differ between lakes that experience similar selective pressures?

• A. The lakes always converge to the same trait due to identical pressures.
• B. Random chance is the only factor determining trait divergence.
• C. Differences in genetic background, standing variation, gene flow, and local ecological differences can yield different evolutionary trajectories.
• D. Morphology is unaffected by gene flow.

Answer: (C)

Even when lakes face similar selective pressures, the evolutionary path a population takes depends on the genetic material available and how populations interact. The starting genetic background matters: what variants exist already, how common they are, and how much standing variation there is for the trait. Gene flow between lakes can move alleles across populations, either spreading helpful variants and reducing differences, or introducing new genetic options that steer adaptation in different directions. Local ecological differences—such as distinct prey communities, microhabitats, or climate nuances—can shift which traits are favored, leading to different adaptive outcomes even under the same overall pressures. Historical events and random drift, especially in smaller populations, can also push populations along different trajectories. Put together, these factors explain why trait divergence can vary instead of always following the same path.

Even when lakes face similar selective pressures, the evolutionary path a population takes depends on the genetic material available and how populations interact. The starting genetic background matters: what variants exist already, how common they are, and how much standing variation there is for the trait. Gene flow between lakes can move alleles across populations, either spreading helpful variants and reducing differences, or introducing new genetic options that steer adaptation in different directions. Local ecological differences—such as distinct prey communities, microhabitats, or climate nuances—can shift which traits are favored, leading to different adaptive outcomes even under the same overall pressures. Historical events and random drift, especially in smaller populations, can also push populations along different trajectories. Put together, these factors explain why trait divergence can vary instead of always following the same path.