Which of the following selection pressures is responsible for the limited evolutionary changes experienced by alligators and other crocodilians?
a. stabilizing selection
b. directional selection
c. disruptive selection
d. high mutation rate

the answer is A ,i just took the unit test review test

a. Stabilizing selection

Stabilizing selection is the type of natural selection in which intermediate traits in an organism is selected by the nature and those with extreme characteristics or trait does not get any benefit. The organisms with intermediate characteristics are suitable for the environment and hence, selected by the nature. These organisms exhibit  limited number of adaptations. Hence, they experience limited evolutionary changes.

Stabilization selection is a selection pressure which is responsible for the limited evolutionary changes experienced by alligators and other crocodilians.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.