genetics chapter 20

quantitative genetics and multifactorial traits

quantitative

continuous characteristics (not 1/0)

polygenic

means that multiple gene effect the phenotype

additive

____ alleles contribute equally to the quantitative phenotype (A, a+ or +)

non-additive

________ alleles do not contribute to the phenotype (nothing, a0, or a-)

environment

the _______ can also influence phenotype. This combined with a polygenic phenotype can give rise to many different complex relations between genotype and phenotype.

overlap

There is an _____ between phenotypic ranges of different genotypes!

meristic

characters that are determined by multiple genes and the environment, but are limited to intergers (1, 2, 3)

Threshold

characters that are determined by multiple genes and the environment, but are either present or absent based off a zone

multiple-gene

The _______________ describes the inheritance of continuous characteristics.

loci

N equals the number of ___ that affect the phenotype

n

1/(4^_) = how many of the extreme phenotype found

2n + 1

The second equation, set equal to the number of distinct categories found

increases

As the number of loci increases, the number of distinct categories ______

normal

a ______ distribution is one where a large number of factors contribute to a measurement. bell shaped

mean

(x), average and center of distribution

variance

(s^2), indicates variability of group, amount of spread in distribution

deviation

The standard _____ (s), indicates the spread within standard variables (66, 95, 99.7)

phenotype

______ correlation- could be caused by environmental or genetics correlations

genetic

_____ correlation, often the result of pleiotropy (one gene that affects many characteristics)

positive

____ correlation is when a gene causes an increase in one trait, the other increases as welln

negative

_____ correlation is when a gene causes an increase in one trait, it causes a decrease in the other

heritability

proportion of a total phenotypic variation that is due to genetic differences __within a population__

fixed

heritability is NOT ____ for a trait! due to changes in environment and genotype

high

___ heritability indicates that gene expression has a greater impact than environment

low

__ heritability indicates that gene expression has a lesser impact than environment

genetic

____ variance (Vg) different phenotypes in a population due to different genotypes

environmental

_______ variance (Ve)- due to environmental differences

interaction

Genetic-Envronmental _____ (Veg) effect the gene depends on environment

additive

genetic variance which has an additive effect of genes on phenotype

dominance

_____ genetic variance (Vd) not additive, some genes have larger impact

interaction

Genic ______ Variance (Vi) gene at different loci may interact like alleles at the same locus (not additive)

broad

____ sense heritability- H^2 = Vg/Vp yields proportion of phenotypic variance from genetic variance (0 means none were from genetic variance, 1 means all)

narrow

_____ sense heritability used to determine the proportion of phenotypic variance due to additive genetic variance (Va/Vp = H^2)

natural

____ selection - differential reproduction, individuals with certain characteristics/genotypes produce more offspring

artificial

_____ selection- we chose which alleles get passed down, can be used to test for heritability

response

___ to select (R) is the extent to which a characteristic subjected to selection changes in 1 generation

narrow-sense, S

The R is determined by ______ heritability (resemblance of parents to offspring) and Selection Differential (_), which is the difference between mean and phenotype of original population (R = H^2 x S)

realized

____ heritability is one determined by the response to selection experiment (H^2 = R/S)

change

R or response to selection measures how much of a _____ in mean there is

extreme

S or selection differential measures how ____ the parental genotypes are

limit

there is a ____ when it comes to natural selection and competing genes (turkeys mass)

unrelated

When comparing relatedness of parent offspring, use heritability of _____ individuals

environment

With identical twins they are (assumedly) genetically identical so all differences in phenotype could be placed on the _________

markers

Quantative Trait Loci or QTLs are genes that control polygenic traits, you can compare using _____

e

_QTLs are loci that regulate the expression of 1 or more genes involved in quantitive traits