Question

Dry conditions caused the water level in a lake to lower over time, and eventually the one large lake became two smaller lakes. As a result, a fish species that lived in this lake was also separated into two groups. The food sources and predators differed between the two lakes. After thousands of years, water levels increased, and the separate lakes became one large lake again. Which of the following is most likely to occur?

A. The fish species will evolve into two separate species.
B. The fish species will become extinct.
C. The fish species will interbreed and remain a single species.
D. The fish species will migrate to other lakes.

Answer 1

The fish species that lived in a split lake environment are most likely to interbreed and remain a single species when the lake merges again, as speciation is unlikely to have occurred over a few thousand years.

Step-by-step explanation:

After thousands of years of separation, the fish species that were divided into two groups due to the drying and subsequent splitting of their lake habitat are most likely to interbreed and remain a single species (C) when the water levels increase and the separate lakes become one large lake again. This is because the two populations were not isolated long enough to undergo significant evolutionary changes that would prevent them from interbreeding, known as speciation. Therefore, the process that would have led to the fish evolving into two separate species, as has occurred in other scenarios such as with cichlid fish in Lake Victoria through sympatric speciation, is unlikely to have been completed in this case. The continuous change and adaptation to different environments, such as different feeding habits and predator pressures, do impact the evolution of populations, but a reunion after a few thousand years would likely result in the two fish populations mingling and genetically mixing once again.