Final answer:
Population variation is the distribution of phenotypes in a population due to factors other than environmental influences.
Step-by-step explanation:
Population variation is the distribution of phenotypes in a population that is due to variation in factors other than environmental influences. These variations can be caused by genetic factors, such as different alleles of a gene, or non-genetic factors, such as the environment. Natural selection acts on the genetic variations, selecting for traits or behaviors that are beneficial for survival and reproduction. For example, in a population of mammals living near the poles, individuals tend to be larger to conserve heat.