How do polygenic traits influence phenotypes?
A polygenic trait is one whose phenotype is influenced by more than one gene. Traits that display a continuous distribution, such as height or skin color, are polygenic. … Many polygenic traits are also influenced by the environment and are called multifactorial.
Why do polygenic traits have many phenotypes?
Polygenic inheritance differs from Mendelian inheritance patterns, where traits are determined by a single gene. Polygenic traits have many possible phenotypes (physical characteristics) that are determined by interactions among several alleles.
What is the phenotypic ratio of polygenic inheritance?
What is the distribution of phenotypes for polygenic traits?
Polygenic traits in a population often form a bell curve distribution. Natural selection on polygenic traits can take the form of: Stabilizing selection: Intermediate phenotypes have the highest fitness, and the bell curve tends to narrow. Directional selection: One of the extreme phenotypes has the highest fitness.
What do polygenic traits result from?
Polygenic traits are due to the actions of more than one gene and often, their interaction with the environment. These usually result in a measurable range in phenotype, such as height, eye color or skin color. These are known as multifactoral or quantitative characteristics.
Why do polygenic traits show continuous variation?
Because multiple genes are involved, polygenic traits do not follow Mendel’s pattern of inheritance. Instead of being measured discretely, they are often represented as a range of continuous variation.
How can a polygenic trait be easily identified?
Usually, traits are polygenic when there is wide variation in the trait. For example, humans can be many different sizes. Height is a polygenic trait, controlled by at least three genes with six alleles. If you are dominant for all of the alleles for height, then you will be very tall.
Why does a polygenic inheritance show a normal distribution among a population?
In the case of polygenic inheritance: Increasing the number of loci responsible for a particular trait increases the number of possible phenotypes. This results in a phenotypic distribution that follows a Gaussian (bell-shaped) normal distribution curve.
What is an example of polygenic inheritance?
Some examples of polygenic inheritance are: human skin and eye color; height, weight and inteligence in people; and kernel color of wheat. … In polygenic inheritance the “dominant” capital genes are additive, each capital gene adding one unit of color to the genotype.
What is polygenic inheritance give an example?
Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect. Examples of human polygenic inheritance are height, skin color, eye color and weight. Polygenes exist in other organisms, as well.
What does polygenic inheritance refer to?
the heredity of complex characters that are determined by a large number of genes, each one usually having a relatively small effect.