Quantitative Genetics definition
Quantitative Genetics refers to the branch of Genetics that studies variation of a given quantitative characteristic in a given population.
Quantitative Characteristics
There are two types of characteristics in natural populations, those that have a continuous distribution and those that are distributed by classes. Being the most common the characteristics with continuous distribution. That is, the most common characteristics of a natural population are quantitative, such as height or weight.
Since Mendel’s laws are difficult to apply to quantitative characteristics, the need arose to use other types of measures. With this, quantitative characteristics are evaluated using statistical tools. The most used statistical tools are:
- central tendency: mode, normal or bimodal distribution, mean and relative frequency;
- dispersion: variance and standard deviation;
- relationship measures: covariance, correlation coefficient and regression.
Variation of quantitative characteristics may be due to change in a single locus of the gene or in several loci that influence expression of the same phenotype.
Objectives of Quantitative Genetics
The big question surrounding quantitative characteristics is whether or not their variation is influenced by genes. Thus, quantitative genetics aims to assess the extent to which genes and environment interact to influence distribution of a quantitative trait in a given population. If this population is large enough, conclusions can be extrapolated to any other population.
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.
