Ch 13 Flashcards
component of the genetic variance in a character that is attribute to additive effects of alleles
additive genetic variance
evolution of internal factors during development that reduces the effect of perturbing environmental and genetic influences, thereby constraining variation and consistently producing a particular
canalization
natural selection fro specific combinations of traits, such that selection on one trait is correlated with selection on the other
correlated selection
genetic correlation, together with character correlation caused by different environmental conditions
environmental correlation
variation among individuals in a phenotypic trait that is caused by variation in the environment rather than by genetic differences
environmental variance
effect of the interaction between two or more gene loci on the phenotype or fitness whereby their joint effect differs from the sum of the loci taken seperately
epistasis
process whereby a phenotype whose development is triggered by an environmental stimulus evolves to be constitutively expressed
genetic assimilation
correlated differences among genotypes in two or more phenotypic characters, due to pleiotrophy or linkage disequilibrium
genetic correlation
variance in a trait within a population, as measured by the variance that is due to genetic differences among individual
genetic variance
phenotypic variation arising from the difference in the effect of the environment on the expression of different genotype
genotype x environment interaction
proportion of the variance in a trait among individuals that is attributable to difference in genotype (narrow sense is the ratio of additive genetic variance to phenotypic variance)
heritability
set of phenotypic expression of a genotype under different environmental conditions
norm of reaction
accounts for the correlation that may be observed between phenotypic character within a population
phenotypic correlation
Correlation between the state of two or more functionally related characteristics, so that they are advantageously matched in most individuals
phenotypic integration
capacity of an organism to develop any of several phenotypic states, depending on the environment; usually this capacity is assumed to be adaptive
phenotypic plasticity
variance in a trait within a population; it may include both genetic variance and environmental variance
phenotypic variance
chromosome region containing at least one gene that contribution to variation in a quantitative trait
QTL mapping
genetic analysis of continuously varrying characters, often employing statistical descriptions and estimators of variation
Quantitative genetics
heritability of a trait as calculated retrospectively from the change in a population’s mean phenotype, relative to the selection differential that was applied to the character in an artificial selection experiment
realized heritability
change in the mean value of a character over one or more generations due to selection
response to selection
difference between the mean character value in a population before selection, and in the subset of individuals that survive and reproduce
selection differential
slope of the relationship between phenotype and fitness, for a quantitative character, usually taking correlations with other characters into account
selection gradient
mean character value at which a population ceases to respond to continuing directional selection
selection plateau
characteristic that is expressed as discrete states, although the genetic variation underlying it is polygenic
threshold trait
capacity for survival; often refers to the fraction of individuals surviving to a given age, and is contrasted with inviability due to deleterious genes
variability
