Chapter 25 - Population Genetics (NF)

Question 1

Genetic Variation

Answer 1

• much of the phenotypic vartion is hereditary
• is the basis of evoltion; the extent of genetic variation within a population affects the potential to adapt to environmental changes (evolve)
• at the molecular level can be far vaster than at the phenotypic level; allows 2 organisms in the same population to produce the same protein from different genetic sequences

Question 2

What are genotype frequencies?

Answer 2

The frequency of allels in a randomly mating population are p and q. The frequencies of the alleles in the gametes will be the same as the frequencies in the parents.

Only a single generation of random mating is required to produce HW genotypic proportions.

Question 3

Genotype Frequency

Answer 3

The proportion of a particular genotype within a population. Add # of individuals with a specific genotype and divide it by the total number of individuals in a population
* f=frequency; N=number of individuals in a sample
-f(AA)= number of AA individuals/N
-f(Aa)= number of Aa individuals/N
-f(aa)= number of aa individuals/N
-f(AA) + f(Aa) + f(aa) =1

The frequencies of genotypes of the next generation will be p^2, 2pq, and q^2.
Only a single generation of random mating is required to produce HW genotypic proportions.

Question 4

Allelic Frequency

Answer 4

Proportion of a particular allele within a population. Always fewer alleles than there are genotypes. Number and types of alleles have more continuity form one generation to the next; alleles not necessarily changin gbut combinations of alleles to express a phenotype changes.
* f=frequency; N=number of individuals in a sample; n=number of individuals with that genotype
* calculate in 2 different ways, but only at a single locus
From numbers of genotypes:
* p = f(A) =2nAA + nAa/2N
* q = f(a) = 2naa + nAa/2N
* p+q=1
From frequencies of genotypes:
* p= f(A) = f(AA) + 1/2 f(Aa)
* q = f(a) = f(aa) + 1/2 f(Aa)
* p+q=1

Question 5

Hardy-Weinberg Law

Answer 5

• for an autosomal locus with 2 alleles
• Assumption: the population is large, randomly mating, not affected by mutation, migration, or natural selection
• Prediction 1: the allelic frequencies of the population do not change. Allelic frequencies determine the frequencies of the genotype
• Prediction 2: the genotypic frequencies will stabilize after one generation
• When assumptions are met, reproduction alone does not alter allelic or genotypic frequencies, and the allelic grequencies determine the frequencies of genotypes.

p^2 + 2pq + q^2 =1

Question 6

Assumptions of Hardy-Weinburg Law

Answer 6

1. assumes that the population is infinitely large at the theoretical level.
   * in practice, large populations have genotypes that are predicted within HW
   *

Question 7

Implications of Hardy-Weinburg Law

Question 8

Extensions of HW law

Question 9

Estimating allelic frequencies with the HW law

Question 10

What is the affect of nonrandom mating?

Question 11

How does inbreeding affect progeny?

Question 12

What is the inbreeding coefficient?

Question 13

What are the implications of inbreeding?