exam 2 ch 9 Flashcards
The study of continuous phenotypic traits and their underlying mechanisms.
Evolutionary quantitative genetics
Traits whose phenotypes occur on a continuum.
Continuous variation
starts with alleles for a genetic loci and builds from genotype to phenotype
population genetics
starts with the distributions of phenotypic values in a population and then determines the mechanisms like selection that caused these distribution of phenotypes to change overtime
quantitative genetics
A trait for which phenotypes fall into discrete categories
qualitative traits
A trait for which phenotypes do not fall into discrete categories, but instead show continuous variation among individuals
Quantitative traits
A locus at which there is genetic variation, that contributes to the
phenotypic variation in a quantitative trait
Quantitative trait loci (QTL)
A collection of techniques that allow researchers to identify chromosomal regions containing loci that contribute to quantitative traits
QTL mapping
Alleles fixed by natural selection, would exert small effects on the phenotype
option 1 of QTL mapping
Some alleles fixed by natural selection will exhibit large phenotypic effects.
option 2 of QTL mapping
a known loci that easily distinguishes between parents (NOT involved in the phenotype you
are examining).
marker loci
Sequencing the genomes of many individuals looking for SNP’s that occur
more frequently in individuals with a specific trait (or disease) compared to those without the trait.
Genome-Wide Association Studies (GWAS or GWA)
A genomic variant at a single base position in the DNA.
Single nucleotide polymorphisms (SNP’s)
Represents the association’s statistical significance as −log 10 (P-value) in the y-axis against chromosome
coordinates, with each dot representing a SNP
Manhatten Plot
Total phenotypic variation (VP) =?
genetic Variation (VG) + environmental Variation (VE)
That fraction of the total phenotypic variation in a population that is caused by genetic differences among individuals
Broad-sense heritability (H2)
Genetic variation (VG) can be broken into 2 parts?
Additive genetic variation (VA)
Dominance genetic variation (VD)
Variation among individuals due to the additive effects of genes
Additive genetic variation (VA)
Variation among individuals due to gene dominance
Dominance genetic variation (VD)
That fraction of the total phenotypic variation in a population that is due
to the additive effects of genes
Narrow-sense heritability (h2)
The average of the parents
midparent value
The average of the offspring in a family
mid offspring value
it tells us that selection acting on the trait will cause a population to evolve
heritability is closer to 1
it tells us that altering the environment can shift a population’s trait distribution
heritability is closer to 0
When selective pressures select against the two extremes of a trait
Stabilizing Selection
A change in allele frequency that occurs when an environmental change favors an extreme phenotype
Directional Selection
Selection that does not favor the most common variation in a population
Disruptive selection
predicted response to selection?
heritability (slope)?
selection differential?
R =
h2 =
S =
The ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions
Phenotypic Plasticity
interaction of genes with the environment
(Vgxe)
The pattern of phenotypic plasticity exhibited by a genotype
reaction norm
