Search results
Results From The WOW.Com Content Network
Phenotypic variation (due to underlying heritable genetic variation) is a fundamental prerequisite for evolution by natural selection. It is the living organism as a whole that contributes (or not) to the next generation, so natural selection affects the genetic structure of a population indirectly via the contribution of phenotypes.
Ronald Fisher in 1913. Genetic variance is a concept outlined by the English biologist and statistician Ronald Fisher in his fundamental theorem of natural selection.In his 1930 book The Genetical Theory of Natural Selection, Fisher postulates that the rate of change of biological fitness can be calculated by the genetic variance of the fitness itself. [1]
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
Environmental variance can be explicitly modeled by studying individuals across a broad range of environments, although inference of genetic variance from phenotypic and environmental variance may lead to underestimation of heritability due to the challenge of capturing the full range of environmental influence affecting a trait.
Examples of human phenotypic variability: people with different levels of skin colors, a normal distribution of IQ scores, the tallest recorded man in history - Robert Wadlow - with his father. Human variability, or human variation, is the range of possible values for any characteristic, physical or mental, of human beings.
The number of QTLs which explain variation in the phenotypic trait indicates the genetic architecture of a trait. It may indicate that plant height is controlled by many genes of small effect, or by a few genes of large effect. [citation needed]
This classic behaviour genetic model aims to partition the phenotypic variance into three categories: additive genetic variance (A), common (or shared) environmental ...
Directional selection can change the genotypic and phenotypic variation of a population and cause a trend toward one specific phenotype. [6] This selection is an important mechanism in the selection of complex and diversifying traits, and is also a primary force of speciation. [ 7 ]