Population Genetics is concerned with the determination of the genetic structure of human population and the analysis of the factors that maintain or alter their genetic structure.The web of genetic relationships among consanguinity,mating patterns,gene flow and natural selection are all significant in the study of human populations.
The various concepts and principles that are used in Population Genetics are
Mendelian Population- The genetic approach to human population generally uses the concept of Mendelian population defined by Theodosius Dobzhansky as follows
A reproductive community of sexual and cross fertilizing individuals which share in a common gene pool.
Each Mendelian population may contain several other smaller Mendelian population within it.The largest Mendelian population is a species because species do not share the same gene pool.They are distinct and are closed genetic system.
One of the important characteristics of a Mendelian population is that it is breeding isolate.A breeding isolate is a small or larger population in which its members find their mates within the group itself.This may be due to several factors such as geographical,social,cultural,linguistics,religious and even psychological.As a consequence of prolonged breeding isolation differences in the genetic make up between different groups of human populations develop.In other words there are differences in gene frequencies between one population and the other.
The determination of gene frequencies depends on sampling,counting and statistical manipulation of numbers.The estimation of gene frequencies is based on Mendel's two principles and on the Equilibrium Law that describes population gene frequencies under certain conditions.