Chapter 17 Vocab

quantitative genetics

genetic analysis of complex characteristics

frequency distribution

a concise graphical method of summarizing values; in genetics, the phenotypes found in a group of individuals are usually displayed using this

normal distribution

common type of frequency distribution that exhibits a symmetrical, bell-shaped curve; usually arises when a large number of independent factors contribute to a measured value

mean (average)

statistic that provides information about the center of a distribution of measurements (ex: the dashed line in the middle of a bell curve)

variance

statistic that describes the variability of a group of measurements

heritability

proportion of total phenotypic variation that is due to genetic differences

phenotypic variance

measure of degree of phenotypic difference among a group of individuals; composed of genetic, environmental, and genetic-environmental interaction variances

genetic variance

component of phenotypic variance that is due to genetic differences among individual members of a population

environmental variance

component of phenotypic variance that is due to environmental differences among individual members of a population

genetic-environmental interaction variance

component of phenotypic variance that results from an interaction between genotype and environment that causes genotypes to be expressed differently in different environments

additive genetic variance

component of genetic variance that comprises the additive effects of genes on the phenotype

dominance genetic variance

component of genetic variance that can be attributed to dominance (interaction between genes at the same locus)

gene interaction variance

components of genetic variance that can be attributed to gene interaction (interaction between genes at different loci)

Broad-sense heritability

proportion of phenotypic variance that can be attributed to genetic variance

narrow-sense heritability

proportion of phenotypic variance that results from the additive genetic variance

quantitative trait loci (QTLs)

a chromosomal region containing genes that control polygenic characteristics

natural selection

differential reproduction of individuals with different genotypes

artificial selection

selection practiced by humans that promotes the reproduction of organisms with traits they perceive as desirable

response to selection

the extent to which a characteristic subjected to selection changes in one generation; equals the selection differential times the narrow-sense heritability

selection differential

difference between the mean phenotype of the selected parents and the mean phenotype of the original population

realized heritability

heritability determined by a response-to-selection experiment