What are the phenotypes like for a polygenic trait?
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.
What type of curve represents the frequency of phenotypes for a typical polygenic trait?
Such phenotypes are often called polygenic traits, and they typically form a spectrum, taking many slightly different forms. Plotting the frequency of the different forms in a population often results in a graph with a bell curve shape. Height (see graph below) and many other traits in humans are polygenic.
Why would a graph showing the frequency of the number of dominant alleles for polygenic traits be a bell-shaped curve?
when frequency of number of dominant alleles is graphed, result is a bell-shaped curve. shows that more of the intermediate phenotypes exist than do the extreme phenotypes. done to compare role of environmental and genes. identical twins (one egg) can hep show genetic contributions from environmental conditions.
Do polygenic traits have all or none phenotypes?
Polygenic traits have all-or-none phenotypes. The individual genes that contribute to a polygenic trait are dominant or recessive to each other. The graph of the frequency of phenotypes in a polygenic trait has the shape of a bell curve. Polygenic traits may be influenced by the environment.
How can the same genotype result in multiple phenotypes?
However, when the same genotype is subjected to different environments, it can produce a wide range of phenotypes. These phenotypic variations are attributable to the effect of the environment on the expression and function of genes influencing the trait.
What information can be obtained from a punnet square?
A Punnett square is a chart that allows you to determine the expected percentages of different genotypes in the offspring of two parents. A Punnett square allows the prediction of the percentages of phenotypes in the offspring of a cross from known genotypes.
What does the number of phenotypes produced for a given trait depends upon?
The number of phenotypes produced for a given trait depends on how many genes control the trait. 15.
What does the allele frequency have to total in the Hardy-Weinberg equilibrium?
In addition, the sum of the allele frequencies for all the alleles at the locus must be 1, so p + q = 1. … In population genetics studies, the Hardy-Weinberg equation can be used to measure whether the observed genotype frequencies in a population differ from the frequencies predicted by the equation.
When individuals at only one end of a bell curve of phenotype frequencies have high fitness The result is *?
Directional selection occurs when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
When the phenotypic expression of a character is controlled by two or more than two genes or alleles it is due to?
What is polygenic inheritance? Polygenic inheritance, in simple terms, implies a character or phenotypic trait, which is regulated by more than one gene. In biology, it refers to the quantitative inheritance wherein two or more independent genes additively affect a single phenotypic trait.
What determines how often a phenotype occurs in a population?
To compare different phenotype frequencies, the relative phenotype frequency for each phenotype can be calculated by counting the number of times a particular phenotype appears in a population and dividing it by the total number of individuals in the population.
When would allele frequencies change in a population?
Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population, the population violates the Hardy-Weinberg assumptions, and evolution occurs.
What type of distribution do we expect the phenotypes of a quantitative trait to demonstrate in a population?
Because quantitative traits exhibit a continuous distribution of phenotypes, they cannot be analyzed in the same manner as traits controlled by a few genes. Rather, these traits are described in terms of statistical parameters. The two primary statistic s used are the mean and the variance.
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 environment interact and affect phenotypes?
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.