Prof. Dr. Sohan Raj Tater
In the study of heredity the first question that arises is how the genotype of an individual is formed from the constituents of the genotypes of his parents. This is the genetics of individual or basic genetics. One may also enquire how the genotype in a fertilized egg cell influences the developmental pattern of organisms and thus realizes its potentialities. This is the developmental genetics. An individual, at least an individual of a sexually reproducing species, is not, however, biologically complete in itself. Its biological role is actualizing through its membership in a reproductive community, a mendelian population. A mendelian population consists of individuals among whom mating may or do occur. An individual is mortal and temporary; a mendelian population has a continuity through time. The genetic process in mendelian populations are the subject matter of population genetics. Population genetics has been defined as the study of the precise genetics composition of population and various factors determining the incidence of inherited traits in them.[41]
Population genetics is founded on a principle enunciated independently by Hardy in England and Weinberg in Germany in 1908. Let us consider the results when a human population consisting of tall (TT), intermediate (Tt) and short (tt) individuals were allowed to mate at rendom. Even after several generations of interbreeding it will be found that there will be some individuals who all tall (TT) some intermediate (Tt) and some short (tt). In other words, we cannot produce a race which is pure or uniform in height.
he Hardy-Weinberg law states that "the relative frequencies of each gene allele tends to remain constant from "generations to generation" in the absence of forces that changes the gene frequency. Thus, the study of gene frequencies, and the influences which operate to after the "gene pool" and their long term consequences is the central theme in population genetics.
Doctoral Thesis, JVBU