Quantitative Genetics Flashcards
breeder’s equation 1
Δ 𝒛ˉ = S · h2
breeder’s equation 2
Δ 𝒛ˉ = G · β
environmental variance
smooths distribution of phenotypes with discrete traits - does not work for continuous (qualitative) traits
combinatorial genetic effects…
smooth distribution of phenotypes linked to quantitative traits
ex. human heights are caused by combining different genetic factors
selection gradient (β)
describes continuum of fitness
i.e. amount of a trait vs. relative fitness
analogous to selection coefficient
fitness functions
describes continuum of fitness - expected phenotype vs expected survival
which is faster - one big step or lots of little phenotypic steps
lots of little steps!
greater variance -> faster evolution
increased standing variation ______ the survival of populations
benefits
h2 (heritability)
slope of regression between parent and offspring phenotype
always less than or equal to 1
s (selection differential)
difference between the avg of the trait before and after selection
G stands for…
genetic variance [average of (x-μ)^2]
P stands for…
phenotypic variance
how to find h2
h2 = G / P
how to find s
S = P x β
greater genetic variance (G) leads to…
larger shifts in traits per generation - greater Δ 𝒛ˉ
G in larger populations
increases
past method to determine genetic cause of a quantitative trait
mate 1 phenotype to the other and score the phenotypes of the descendants - can determine which traits are in linkage with the trait of interest
genetic architecture
figuring out which genes cause a phenotype - can be used to find a single causal loci, or polygenic loci
GWAS
genome wide association study
measuring phenotypes and sequencing genotypes of living individuals, looking for statistically significant individuals
cryptic population structure
we don’t really understand the genetic interconnectedness of populations in the past, making it hard to understand associations
* complex and not gone over very much
requirements for GWAS
large sample size and an environment that is as controlled as possible
more loci involved in a trait ->
larger adaptive phenotypic leaps are taken
coalescence
most lineages die out due to genetic drift
looking at the distribution of old (common) and new (rare) mutations can tell us about changes in population sizes over history
