The differences between marine and freshwater sticklebacks
A) are mainly induced by environmental conditions.
B) arise due to changes in the expression of a transcription factor.
C) are an example of genetic differences that do not cause phenotypic differences.
D) are the result of a mutation in a single population of freshwater sticklebacks.
E) probably have no selective advantages.

Question

Quizplus · Accepted Answer

The differences between marine and freshwater sticklebacks arise due to changes in the expression of a transcription factor. The transcription factor called Pitx1 is involved in the development of pelvic fins in sticklebacks. The expression of Pitx1 is reduced in freshwater sticklebacks, resulting in a loss of pelvic fins that is adaptive in their environment.

The Differences Between Marine and Freshwater Sticklebacks