Question

Guppies exhibit sexual dimorphism in some pools due to intersexual selection, but the frequency of brightly colored males in a population varies depending on environmental factors such as the presence or absence of predators in the pool. Which of the following would you expect to occur in a captive population of guppies collected from Trinidad, if you allowed them to breed for many generations in an aquarium WITHOUT predators?

Group of answer choices
a. Female guppies will become more brightly colored.
b. Male guppies that are brightly colored will have better reproductive success than dull males.
c. The number of dull-colored male guppies will eventually equal the number of brightly colored males.
d. Female guppies will prefer to mate with the dull-colored males.

Answer 1

In the absence of predators, male guppies that are brightly colored in a captive Trinidad population would likely experience better reproductive success due to female preference, as supported by John Endler's research which demonstrates genetic variability and the tradeoff between bright coloration for mating and camouflaging to avoid predation.

Step-by-step explanation:

In a captive population of guppies collected from Trinidad, if allowed to breed for many generations in an aquarium without predators, one would expect male guppies that are brightly colored to have better reproductive success than dull males. This is due to sexual selection, where female guppies have a preference for mating with more colorful males when the threat of predation is absent.

John Endler's research supports this notion, as he found that in the absence of predators, guppies exhibited more conspicuous colors due to sexual selection preferences. The experiment conducted by Endler illustrates the existence of genetic variability in guppy populations, as the drab-colored guppies introduced to a predator-free area developed brighter colors over time, signifying that the potential for brighter coloration was present in their genetic makeup.

This change in guppy coloration highlights the tradeoff between attracting mates with bright colors and avoiding predation. In an environment with no predators, the selection pressure for camouflage is reduced, allowing sexually attractive traits to become more prevalent.