LEC 11 - BIO 30

analyzes genetic and environmental factors, specifically, how these influence the inheritance and expression of quantitative traits

quantitative genetics

controlled by 1-2 genes

qualitative characters

less environmental influence

qualitative characters

classes are easily recognizable

qualitative characters

characters are observed by visual inspection

qualitative characters

controlled by many genes

quantitative characters

great environmental influence

quantitative characters

classes are not easily recognizable

quantitative characters

characters are in measurable units

quantitative characters

shows continuous variation

quantitative characters

shows discontinuous variation

qualitative character

continuous variation is due to multiple genes, every gene has a small effect on the character

yule

as the number of independent genes are increased, distribution follows a normal curve - studied grain color in wheat

herman nilsson-ehle

proposed the term polygenes

mather

group of genes that influence the expression of a quantitative trait in an additive manner

polygenes

distributed in a continuous manner in a population and can be measured

metric characters

anatomical dimensions such as body weight, height, head size, limb length

metric characters

grain yield, seed size, meat yield

economic characteristics

measure of the variability of a trait / variance due to phenotype

phenotypic variance

formula for phenotypic variance

vp = vg + ve + vgxe

due to genetic differences among individuals / different genotypes within the group

genotypic variance

non genetic sources of variation / different environments experienced by the individuals

environmental variance

occurs wgeb the relative effects of the genotypes differ among environment, both environmental and genotypic differences contribute to vp

genotype x environment interaction

components of vg

vg = vd + vi + va

one allele masks the expression of the other allele at a locus

dominance vd

alleles at different loci interact to determine the phenotype

epistasis vi

consider the contribution of each contributing allele

additive va

proportion of a population’s phenotypic variation that is attributable to genetic factors

heritability

used to examine the relative contributions of genes and environment to variation in a specific trait

heritability

how much of the phenotypic variance can be attributed to genetic variance

broad sense heritability

allows accurate prediction about the resemblance between offsprings and parents, proportion of phenotypic variance that results from va

narrow sense heritability