What term describes the geographical gradient in the distribution of a phenotypic trait from one population to another?

The term that describes the geographical gradient in the distribution of a phenotypic trait from one population to another is "cline." A cline represents a gradual change in the frequency of a phenotypic trait or allele across a geographical area, often corresponding to environmental gradients. This concept is essential in understanding how traits can vary systematically among populations that are located in different environments or regions.

The significance of a cline lies in its ability to illustrate how environmental factors can influence genetic variation and adaptations within populations. As one moves through the geographical range, the changes in traits might correlate with factors like climate, altitude, or availability of resources, reflecting the interplay between genetics and environment.

In contrast, genetic drift refers to random changes in allele frequencies in small populations due to chance events, which does not specifically address geographical distribution. A phylogenetic tree is a diagram that shows the evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics, not focusing on geographical traits. Migration pertains to the movement of individuals or populations from one location to another but does not inherently describe the gradient of phenotypic traits across spaces.