Biology 12 Population genetics and evolution

What are some mechanisms of microevolution?

1. Natural selection (best suited organisms will survive)

2. Genetic drift (chance events change alleles)

3. Gene flow (new alleles enter the population)

What are the mechanisms of genetic drift?

1. Founder effect: individuals from a population become isolated and reduce the gene pool in the new population

2. Bottleneck effect: population goes through a “bottleneck” that decreases the population size, smaller population may have different alleles just by chance

How do we determine if a population is evolving?

We determine the theoretic allele and genotype frequencies that would exist if the population was not evolving, then we would determine the actual population frequencies and see if they differ from the expected alleles and genotypes

What is a gene pool?

All the alleles present in a population at a particular time.

What do homozygous and heterozygous represent?

Homozygous represents having two copies of the same allele and heterozygous represents having one copy each of two different alleles

What is the Hardy-Weinberg equilibrium? What assumptions must be made to use it?

Predicts the number of genotypes that would occur in the offspring of a population that is not evolving. We must assume:

1. The population size is large and there is no genetic drift

2. Mating occurs at random, no sexual selection

3. There is no immigration or emigration, so no gene flow

4. No new alleles, so no mutations

5. No natural selection is occuring

If given the proportions or frequencies of alleles in a Hardy-Weinberg equilibrium, how would we predict the proportion of genotypes in the next generation?

p²+2pq+q²

What are the mechanisms of evolution?

1. Mutations

2. Genetic drift

3. Gene flow / migration

4. Natural selection