Population Genetics definition
Population Genetics refers to the branch of Genetics that studies the genetic constituent of a population. It focuses specifically on hereditary alterations that occur in a population, in time and space. And tries to develop an evolutionary theory that explains and predicts such changes.
Objectives of Population Genetics
Population Genetics is responsible for bridging the three principles of Darwin’s Theory of Evolution and precise genetic terms. Darwin’s Theory of Evolution states:
- among individuals of any population, there is morphological, physiological and behavioral variation (principle of variation);
- offspring will be more like their progenitors than any other individual within the population (heredity principle);
- there are different forms of survival, some being more effective than others (survival principle).
Taking this into account, it can be deduced that population genetics studies genotypic alterations, however it is only possible to observe phenotypic variations. Due to this constraint, most studies in population genetics are performed with features that have a direct correlation with their genotype. In this field of investigation, Gregor Mendel, in 1843, played an important role with his study of characters of peas.
Characteristics of Population Genetics
For the study of variations in a population a process with two stages is necessary: in the first stage, phenotypic variations are visualized; and in the second stage attempts are made to associate these phenotypic changes to variations in genotype of the species in question.
The most widely used measure in this field of genetics is measurement of frequency at which certain alleles are found in the gene under study. This frequency can be altered due to mutations (gene and/or chromosomes), selection (natural or artificial) and migrations. Recombination (a type of chromosomal mutation) seems to be the one that most contributes to change in frequency of an allele.
References:
Alberts B., Johnson A., Lewis J., Raff M., Keith R., Walter P. (2007). Molecular Biology of the Cell (5th edition). Garland Science, New York.
Griffiths A.J.F., Miller J.H., Lewontin R.C., Gelbart W.M. (1999). Modern Genetic Analysis (2nd edition). W. H. Freeman, New York.
Griffiths A.J.F., Wessler S.R., Lewontin R.C., Gelbart W.M., Suzuki D.T., Miller J.H. (2004). An Introduction to Genetic Analysis (8th edition). W. H. Freeman, New York.
