A biologist is studying jaw size in a population of Atlantic wolf fish (also called sea wolves). She notes that specimens

Question

A biologist is studying jaw size in a population of Atlantic wolf fish (also called sea wolves). She notes that specimens collected in 1922 had a jaw width of 8±4, but the present-day population has a jaw width of 8±2.5. Of the following options, which is the most likely explanation?
a. Directional selection took place in this population over the past century.
b. Stabilizing selection took place in this population over the past century.
c. Disruptive selection took place in this population over the past century.
d. Natural selection was not acting upon tooth length in this population, because the mean value for tooth length stayed the same.
e. Genetic drift caused an increase in the phenotypic variation in this population.

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