Question

Two species of Drosophila have been competing in the lab for a long time. A researcher notes that over the course of time, the competition coefficients of these species have become smaller. What is the most likely explanation of this change?

1) Periodic disturbances
2) Allelopathy
3) Character displacement
4) Competitive exclusion

Answer 1

Character displacement is the probable cause for the observed decrease in competition coefficients between the Drosophila species, as it leads to species adapting distinct traits to reduce competition and coexist.

Step-by-step explanation:

The reduction in competition coefficients between two species of Drosophila suggests that these species have undergone an evolutionary change that allows better coexistence in a shared environment. The concept behind this observation is character displacement, a process where species evolve distinct traits that decrease competition over time when they live in the same geographic area and compete for the same resources. This evolutionary change often involves the diversification of physical or behavioral traits that reduce direct competition for resources.

Given the options provided, character displacement is the most likely explanation for the observed decline in competition coefficients. Species may adapt to utilize different resources or develop different behaviors that reduce direct competition, ultimately leading to a decrease in the competition coefficients. This contributes to species coexistence according to the competitive exclusion principle, which implies that no two species can occupy the same niche indefinitely when they compete for the same resources at the same time and place.

In summary, character displacement is an adaptive change that can lead to species coexistence and is the probable cause for the decreasing competition coefficients observed by the researcher in the Drosophila species.