Quick Answer: In what type of situation does a phenotypic distribution look like a bell shaped curve?

What type of situation does a phenotypic distribution look like a bell-shaped curve?

Blending is now known as continuous variation, describing a gradation in expression in which phenotypes (such as human height) do not fall into distinct categories. When a trait that exhibits continuous variation is plotted on a graph, the phenotypic distribution forms a bell-shaped curve.

What is shown in a phenotypic distribution?

The phenotypic distribution of a trait, as we have seen, is a function of the average differences between genotypes and of the variation between genotypically identical individuals. … For a given genotype, each environment will result in a given phenotype (for the moment, ignoring developmental noise).

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What are 3 ways to change the normal distribution bell curve of phenotypes?

Natural selection on polygenic traits can affect the distributions of phenotypes in three ways: directional selection, stabilizing selection, or disruptive selection.

Which type of selection favors traits on both extremes of the bell curve?

Disruptive selection occurs when both extreme phenotypes are favored, while individuals with intermediate phenotypes are selected against by something in nature.

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.

What traits tend to result in a phenotypic distribution that resembles a bell-shaped curve?

Polygenic traits tend to result in a distribution that resembles a bell-shaped curve, with few at the extremes and most in the middle.

What is the type of natural selection in which phenotypes in the middle of the phenotypic distribution are selected against?

Disruptive selection occurs when phenotypes in the middle of the range are selected against. This results in two overlapping phenotypes, one at each end of the distribution.

Which type of natural selection selects against extreme phenotypes?

Stabilizing selection results in a decrease of a population ‘s genetic variance when natural selection favors an average phenotype and selects against extreme variations. In directional selection, a population’s genetic variance shifts toward a new phenotype when exposed to environmental changes.

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What type of natural selection selects for the average phenotype of a polygenic traits in a population?

stabilizing selection

type of natural selection for a polygenic trait in which phenotypes at both extremes of the phenotypic distribution are selected against, resulting in a narrowing of the range of phenotypic variation.

What produces a phenotype?

An organism’s phenotype results from two basic factors: the expression of an organism’s genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype.

What is normal distribution quizlet?

Normal Distribution. a bell-shaped curve, describing the spread of a characteristic throughout a population. Two Pieces of data that specify a Distribution. Mean (μ) and Standard Deviation (σ)

Why is the distribution of a quantitative trait that of a bell curve?

Terms in this set (32) Study of traits that exhibit continuous variation. Quantitative genetics are controlled by many genes and they are affected by the environments. … Qualitative genetics are controlled by only one or two genes.

In which type of selection is the extreme phenotype favored and the distribution curve shifts that direction?

In population genetics, directional selection, is a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

When the intermediate phenotype is favored the extreme phenotypes are being selected?

Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.

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How does Diploidy preserve genetic variation?

How does diploidy help to preserve genetic variation? It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation of heterozygotes. … The ultimate source of new alleles are mutations, random changes in the nucleotide sequences of an organism’s DNA.