241 - 39 & 40, Quantitative Genetics Flashcards
______ traits are traits determined by several genes acting together
complex
Complex traits are often ______ and influenced by environmental factors
polygenic (traits influenced by multiple genes)
complex traits are _______, meaning having many factors, not only genetic ones
multifactorial
Complex traits can be _______ (continuously varying) or _____ (all-or- nothing)
quantitative (continuously varying) or threshold (all-or- nothing)
In complex traits, individual genes are called _______ ______ ____ (___)
quantitative trait loci (QTL)
In quantitative traits, the relative role of environment and genetics can be determined by looking at the variation in phenotype between genetically _____ organisms as compared to genetically more ______ organisms
pure; diverse
In determining role of env. and genetics, any variation in genetically pure organisms is due to ________
environment
In determining role of env. and genetics, the extra variation in genetically ______ organisms is due to the variability in the genes
diverse
st dev is related to variance how
v^2 = variance
v = st dev
(a.k.a., st dev is square root of variance)
broad-sense heritability equation
H^2 = V_g / V_P
narrow-sense heritability equation
h^2 = V_a / V_P = R / S
difference between broad-sense and narrow-sense
broad is - genetic diff. / total variance
narrow is - additive variance / total variance
total genetic variation equation
V_g = V_d + V_i + V_a
V_g, V_d, V_i, V_a stand for . . .
V_g - total genetic variance
V_d - dominance variance
V_i - epistatic variance
V_a - additive genetic variance
R, S stand for
response, selection
________ traits are polygenic traits in which the phenotype is recorded by counting whole numbers. They are quantitative traits but do not have an infinite range of phenotypes.
Meristic
_______ traits are polygenic and often multifactorial but have a small number of discrete phenotypic classes
Threshold
example of meristic trait
of peas in a pod
example of threshold traits
of predisposing alleles in genotype of clinical diabetes
_______ ______ contribute to a single quantitative character, and the phenotypic contribution of each additive allele is approximately equa
additive alleles
number of genes (n) contributing to a quantitative trait can be estimated based on the ratio of ___ individuals resembling either of the two extreme P1 phenotypes
F2
equation for determining # of genes contributing to a quant. trait
1 / 4^n = ratio of F2 individuals expressing either extreme phenotype
1 / 4^n = ratio of F2 individuals expressing . . .
other extreme phenotype
total phenotypic variance
V_p = V_g + V_e + V_eg
Meaning of: V_p V_g V_e V_i
V_p - phenotypic
V_g - genetic
V_e - environmental
V_eg - envi./genetic
