Final answer:
Heritability is the measure of the ability of a population to produce the same phenotype regardless of environmental or genetic variability. High heritability allows a population to adapt to changing environments and maintain its evolutionary fitness through successful reproduction.
Step-by-step explanation:
Explanation of Phenotypic Stability
The measure referred to in the question is known as heritability. Heritability is the fraction of phenotype variation that can be attributed to genetic differences, or genetic variance, among individuals in a population. The existence of genetic variation within a population contributes to the population's overall fitness and ability to adapt to changing environments.
Given the variability of both environment and genotype, a population that can consistently produce the same phenotypes has high heritability. Heritability affects how a population responds to evolutionary forces and natural selection, ensuring that beneficial alleles are retained through successful reproduction, even in the face of environmental changes. Therefore, the measure of the ability of a population to produce the same phenotype despite variability is tied closely to its genetic diversity and heritability.