Exam 3 Part 1 Flashcards
Discrete traits
no severity/degree
very distinct phenotypes
discrete phenotypes
clearly defined by 1 or a few genes
quantitative traits
measurable in numeric terms
-quantifyable
have continuous variation
continuous variation
phenotypes are distributed along a continuum; sereis of intermediate phenotypes that fall between
2 extremes
quantitative traits controlled by…
multiple genes and environmental factors
quantitative genetics
studyof inheritance of quantitative traits
contributing alleles
additive alleles.
number of copies of these alleles influence the degree of severity of a trait
Alleles A and B result in red pigment, a and b do not product pigment
One gene variates
F2
1:2:1
two gene variation
F2
1:4:6:1
three gene variation
F2
1:6:15:20:15:6:1
distribution
summary of continuous phenotypic variance for a group
population
all individuals
sample
representatitive subset of population
sample should be…
randomly selected - unbiased
large enough
environmental effects on quantitative traits
causes variation within each genotypic class blurred lines between phenotypic classes
how environmental effects are studied
with modern genotyping methods such as PCR
VG
genotypic variance
contribution of alleleic differences at multiple genes
VE
environmental variance
contributions from nongenetic sources
VgxVe
genotype by environment variance
Vp
phenotypic variance
Vp=Vg+Ve=(VgxVe)
heritiability
how much of the phenotypic differences are due to genetic factors
0, 0.5, 1
0 heritiability
none of the variation in phenotype bt individuals results from genetic differences
0.5 heritability
half of the phenotypic variation is due to genetic differences between individuals and half is due to environment
1 heritability
all variation is genetically based
