Final answer:
Heritability is the percentage of variation in a given characteristic that is due to genetic differences within a population. It is key in population genetics for understanding how traits are inherited and how a population may evolve.
Step-by-step explanation:
Heritability is the percentage of the variation in a given characteristic that can be attributed to genetics. This concept is essential in understanding the genetics of inheritance and is a significant factor in population genetics. By analyzing how genetic variation contributes to the phenotypic variation within a population, scientists can determine the heritability of particular traits. There are environmental factors that cause phenotypic variation, but only the genetic differences, or genetic variance, can be passed down to successive generations. Heritability, therefore, determines how much of this variation is due to genetic factors and is critical for predicting how a population will evolve over time under the influence of natural selection, genetic drift, gene flow, and mutations.
When discussing population variation, such as the one observed in Mendel's pea plants, which had different genotypes like homozygous dominant, heterozygous, and homozygous recessive for various traits, heritability helps us understand the genetic basis for these observable differences. In population genetics, the allele frequency and changes in this frequency are central to the study of evolution. For instance, in the study of allele frequencies in the AB blood type system, such as changes in the IA allele frequency, these changes are a reflection of evolution at the genetic level.