CH. 4 Flashcards
Population Genetics*
The study of factors affecting gene and genotypic frequencies in a population.
Gene or Allelic Frequency*
The relative frequency of a particular allele in a pop. Designated by p and q
Genotypic frequency*
The relative frequency of a particular one-locus genotype in a pop. Designated by P, Q, and H
p
The frequency of the dominant allele
q
the frequency of the recessive allele
The effect of selection
Is to increase the gene frequency of favorable alleles. Better set of genes+ better breeding values
Fixation*
The point at which a particular allele becomes the only allele in the pop.
Ex. Purebred black angus
Mating systems
“sets of rules” for determining which selected males is bred to which selected females
Inbreeding
the mating of relatives. increases the frequency of homozygosity but decreases the frequency of heterozygosity.
Outbreeding
the mating of unrelated individuals. Increases the frequency of heterozygousity and decreases the frequences of homozygoisity
half-sibs*
half brothers and/or sisters
Common ancestor*
an ancestor common to more than one individual
pedigree relationship*
relationship between animals due to kinship
Arrow diagram*
A form of pedigree depicting schematically the flow of genes from ancestors to descendants
F1*
Referring to the first generation of crosses between two unrelated (though not necessarily purebred) populations.
F2*
Referring to the generation of crosses produced by mating F1 (first-cross) individuals among themselves
Hardy-Weinburg Equilibrium*
A state of constant gene and genotypic frequencies occurring in a pop in the absence of forces that change those frequencies.
H-W Equation
p^2+2pg+q^2=1
P=p^2
H=2pq
Q=q^2
Assumptions for H-W Equilibrium
organisms are diploid
Only sexual reproduction occurs
Generations are non-overlapping
Mating is random
Pop size is infinitely large
Allele frequencies are equal in the sexes
There is no migration, mutation or selection
Mutation*
Process that alters DNA to create new alleles
Migration *
The movement of individuals into or out of a pop.
Random Drift*
Change in gene frequencies in small pops due purely to chance
