Population genetics - Fish genetics. This area of study uses genotype frequencies to distinguish populations. Populations (in the genetic sense) are groups of interbreeding individuals that rarely exchange members with other populations. Population genetics. This area of study uses genotype frequencies to distinguish populations. Populations (in the genetic sense) are groups of interbreeding individuals that rarely exchange members with other populations. Population genetics - Fish genetics. This area of study uses genotype frequencies to distinguish populations. Populations (in the genetic sense) are groups of interbreeding individuals that rarely exchange members with other populations. Population genetics. This area of study uses genotype frequencies to distinguish populations. Populations (in the genetic sense) are groups of interbreeding individuals that rarely exchange members with other populations.