גנטיקה של אוכלוסיותגנטיקה של אוכלוסיות

Formula for allele frequency, based on knowledge of genotypes

A 3 allele case

p = freq of IB = freq B (IBIB) + ½ freq of B (IBi) + ½ freq of AB (IBIA)q = freq of IA … =r = freq of i… =

p + q + r = 1

In 3 allele case, same mathematical treatment

YET:Populations with different genotypes can have the same allele frequency

BUT, if there are random matings, the genotype frequency of offspring is based on solely on the allele freq.

In next generation

Hardy-Weinberg (H-W) Law

&(Chetverikov)

YET, if there are random matings, the genotype frequency of offspring is based on solely on the allele freq.

In this case:

In next generation

Hardy-Weinberg (H-W) Law

Populations NOT in H-W equilibrium

If the processes below do not occur, a population is in Hardy-Weinberg (HW) equilibrium, the following are unchanged:

Allele frequenciesGenotype frequencies

Phenotype frequencies

TEST: if these populations are in H-W equilibrium, then:

If a population is in Hardy-Weinberg equilibrium,

the allele,genotype, and phenotype frequencies will

be stable as long as the HW requirements hold

H-W בשיווי משקל -- הרבה אכלוסיותאז... תיאור של אכלוסיה לפי תדירויות

מתאים (ו'חסכוני') - של אללים

Genotypefrequencies

2 allele case

Genotypefrequencies

M/M

M/N

N/N

p(M)q(N)

Percent

LocationMMMNNNpq

Iceland31.251.517.300.570.43

Greenland83.515.60.90.920.08

We see HW equilibrium for ‘breeding populations’

We don’t expect HW for, say: the city of New York City Lots of immigration

Not random matings, but many distinct sub-groups

How do HW populations “start” with different allele frequecies? In human populations, often small founder populations:

BUT, MANY human populations are in H-W equilibrium, for example- MN tables we just saw, and:

How do HW populations “start” with different allele frequecies? In human populations, often small founder populations:

Percent

LocationMMMNNNpq

Iceland31.251.517.300.570.43

Greenland83.515.60.90.920.08

If the processes below do not occur, a population is in Hardy-Weinberg (HW) equilibrium, the following are unchanged:

Allele frequenciesGenotype frequencies

Phenotype frequencies

If these processes DOoccur, the populations

change.-Each process can be

studied and quantitated

Selection of allele A: preferential survival

Haplotype

Inbreeding

0.5 X 0.5