Question

If a guppy species found in a stream is placed in a lake, its colour will evolve rapidly from colourful to drab over as few as 10 generations because of the:
A. Lack of food.
B. Presence of additional predators in the lake.
C. Temperature of the air.
D. Taste of the water.

Answer 1

Hint: When any organism is moved from its original habitat to a new one, it might experience some changes. In this case, a change in the type of habitat has caused a change in the colour of the fish. Something is causing stress to the guppy species due to changes in the habitat. This stress leads to phenotypic or genotypic variation. This variation increases their chances of survival.

Step by step solution:
In streams, food will be hard to obtain due to the current of water. But in the lake condition, the water is still. Hence it is easy to get food. So, lack of food can not be the reason to change its colour.
Lake will have more predators as compared to streams due to lack of current. This will also increase the chances of predators preying on guppy species. This will lead to a decrease in their population. To prevent this, they have evolved to have colourless skin. This will make them transparent and will protect them against their predators.
The temperature of the air will be similar in the case of streams and lakes. This will not lead to evolutionary change in the species.
The taste of water does not affect the colour change in the species.

So, option B is correct.

Note: Evolution leads to variation in the species. This leads to the emergence of new, better species. Evolution can happen due to a sudden change in the environment or an advantageous genetic mutation. Due to these stresses or conditions, we can observe bacteria evolve into vertebrates.