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A study of recent polygenic adaptation in the English has shown that selection on height has had small effects on allele frequencies (<1%) across most of the genome, and found evidence for polygenic adaptation in a wide variety of other traits as well including selection for increased infant birth size and increased female hip and waist size. [10]
Human height is a continuous trait meaning that there is a wide range of heights. There are an estimated 50 genes that affect the height of a human. Environmental factors, like nutrition, also play a role in a human's height. Other examples of complex traits include: crop yield, plant color, and many diseases including diabetes and Parkinson's ...
Pleiotropy seems limited for many traits in humans since the SNP overlap, as measured by variance accounted for, between many polygenic predictors is small. Most genetic traits are polygenic in nature: controlled by many genetic variants, each of small effect. These genetic variants can reside in protein coding or non-coding regions of the genome.
Phenotypic plasticity refers to some of the changes in an organism's behavior, morphology and physiology in response to a unique environment. [1] [2] Fundamental to the way in which organisms cope with environmental variation, phenotypic plasticity encompasses all types of environmentally induced changes (e.g. morphological, physiological, behavioural, phenological) that may or may not be ...
Traits controlled by two or more genes are said to be polygenic traits. Polygenic means "many genes" are necessary for the organism to develop the trait. For example, at least three genes are involved in making the reddish-brown pigment in the eyes of fruit flies. Polygenic traits often show a wide range of phenotypes.
For example, crocodiles possess a temperature-dependent sex determining polyphenism, where sex is the trait influenced by variations in nest temperature. [ 3 ] When polyphenic forms exist at the same time in the same panmictic (interbreeding) population they can be compared to genetic polymorphism . [ 4 ]
A polygenic trait is one whose phenotype is dependent on the additive effects of multiple genes. The contributions of each of these genes are typically small and add up to a final phenotype with a large amount of variation. A well studied example of this is the number of sensory bristles on a fly. [23]
Analysis on quantitative trait locus effects has been used to examine the impact of directional selection in phenotypic diversification. QTL is a region of a gene that corresponds to a specific phenotypic trait, and the measuring the statistical frequencies of the traits can be helpful in analyzing phenotypic trends. [9]