Question

How does natural selection explain the differences in coloration between inland and coastal guppies?

Inland guppies evolved bright colors to blend into the local vegetation, while coastal guppies evolved muted colors to signal good health and attract mates.

Inland guppies evolved bright colors to signal good health, while coastal guppies evolved muted colors for camouflage.

Inland guppies evolved muted colors to blend into dense vegetation and avoid predators, while coastal guppies evolved bright colors to improve mate attraction and visual communication.

Inland guppies evolved muted colors for camouflage, while coastal guppies developed muted colors because predators in clear water prefer bright colors.

Answer 1

Correct choice: the second statement.

Why: Natural selection (including sexual selection) produces a trade-off. Where predation risk is high (coastal/lowland sites), conspicuous coloration makes males easy targets, so selection favors muted, camouflaged coloration. Where predation is low (inland/upstream sites), predation relaxes and sexual selection by choosy females favors brighter, more conspicuous males as signals of health and genetic quality. Classic field and experimental work on Trinidad guppies (Endler and others) documents this pattern.

Why the others are wrong:
- Option 1 mixes up functions (bright colors don’t generally “blend” into vegetation) and swaps the proximate explanations.
- Option 3 reverses the observed pattern (bright colors are typically in low-predation inland populations).
- Option 4 is internally inconsistent and incorrect about both groups evolving muted colors.