Allele frequencies can change across the geographic range of a species according to climate, geological features, or direction in the range. for instance, a certain allele frequency might go up along with the elevation or down as you go south in the species' range. this systematic change in frequency is referred to as
a. genetic drift.
b. q2.
c. directional selection.
d. a cline.
e. heterosis.

Cline

Explanation:

Cline refers to a noticeable and gradual change of some phenotypic traits over a geographical region. The phenotypic traits such as body size, coloration, etc. exhibit continuous variation or gradient over a geographical region.

Clines result from geographical variations within a species. Clines are usually related to the gradient of abiotic factors such as temperature, pressure, light, altitude. Gene flow between the populations present along the gradient of abiotic factors results in continuous variations in allele frequencies.

the areas around the equator