What factors cause quantitative variation in a trait within a population?
Variation in a quantitative trait usually results from the contributions of multiple genes with small effects modified by environmental influences. If none of the genes contributes a substantial amount to this quantitative variation, loci can be difficult to detect using linkage analysis.
What factors cause phenotypic variation?
Two types of factors are recognized as contributing to the phenotypic variation in a population, genetic and environmental.
What are the sources of phenotypic variation in a population?
For a given population, there are three sources of variation: mutation, recombination, and immigration of genes.
How do quantitative traits affect phenotypic expression?
Quantitative traits are phenotypic traits that are determined, jointly with the environment, by many genes of small effect. … Compared to neutral genetic markers, quantitative traits are more sensitive to population structure and may suggest differences where neutral genetic markers fail to show any.
How does the distribution of a quantitative trait in a population appear?
Most quantitative traits are continuous; the trait falls within a range of values. … With regard to genetics, a frequency distribution is a graph that compares the number of individuals and their phenotypes for a given trait. This is a common way to depict the distribution of a quantitative trait in a population.
What makes a trait quantitative?
A quantitative trait is a measurable phenotype that depends on the cumulative actions of many genes and the environment. These traits can vary among individuals, over a range, to produce a continuous distribution of phenotypes. Examples include height, weight and blood pressure.
What is phenotype influenced by?
An organism’s phenotype is determined by its genotype, which is the set of genes the organism carries, as well as by environmental influences upon these genes. … Phenotypes also include observable characteristics that can be measured in the laboratory, such as levels of hormones or blood cells.
What is phenotypic variance?
VP, or phenotypic variance, is simply the observed, measured variance in the trait of interest. For instance, if you are studying milk yield, then the observed variation in milk yield among the cows is your VP.
What environmental factors can cause phenotypic variation in plants and animals?
Environment Can Impact Phenotype
Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed, which ultimately affects the animal’s phenotype.
How do you find phenotypic variation?
Variance Components of a Quantitative Trait
- VP = VG + VE + VGE VP = total phenotypic variation of the segregating population. …
- VG = VA + VD + VI and the total phenotypic variance can be rewritten as.
- VP = VA + VD + VI + VE + VGE …
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What are the two main sources of genetic variation?
Natural selection acts upon two major sources of genetic variation: mutations and recombination of genes through sexual reproduction.
What are the three main ways that variations in genotype arise in a population?
Variations in genotype arise by mutation, recombination, and the random pairing of gametes.