The guppy is a species of small freshwater fish. Scientists observed that the average size of guppies in a pond decreased over a few years after a guppy predator was introduced in the pond. Which of the following best explains the change in guppy size?
A) speciation
B) convergent evolution
C) natural selection
nat·u·ral se·lec·tion the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.
C) natural selection
The correct answer is C) natural selection.
To understand why natural selection is the best explanation for the change in guppy size, we need to understand the concept of natural selection and its role in evolution.
Natural selection is a fundamental principle in biology that describes how certain traits become more or less common in a population over time. It occurs when individuals with certain advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring.
In the case of the guppies, the introduction of a predator in the pond likely led to an increased predation pressure on the guppies. The guppies with larger size may have been more visible and easier targets for the predator. As a result, the larger guppies were selectively removed from the population, while smaller guppies had a higher chance of survival due to their ability to hide or escape from the predator. Over time, the smaller guppies became more prevalent in the population, resulting in a decrease in the average size of the guppies in the pond.
Speciation (A) refers to the formation of new species, which is not applicable in this scenario. Convergent evolution (B) describes the process where unrelated species independently evolve similar traits due to similar selective pressures, which is also not relevant in explaining the change in guppy size. Therefore, natural selection (C) is the most appropriate explanation in this case.