Bis2a lecture week 3-Pop. Genetics

How is evolution defined in the context of population genetics,

Any genetic and resulting phenotypic change in organisms from generation to generation

What is a population

A group of individuals of one species that live together, interbreeding with one another.

What is an allele

A specific variant of a gene at a particular locus

What is a genotype

The specific combination of paired alleles carried by an individual organism

What is a gene pool

The sum of all copies of all alleles for a given gene/locus found in a popualtion.

What is “the Counting Method” used to calculate allele frequencies in a population when you do not know if the population is in Hardy-Weinberg Equlibrium

To calculate allele frequencies directly from observed genotype. numbers.

What is a test cross and how is it used to determine an organism’s genotype?

Involves mating an individual displaying a dominant phenotype with a known homozygous recessive individual

If 100% of the offspring shows the dominant phenotype, the unknown parent was…

Homozygous dominant (YY)

If 1:1 phenotypic ratio of dominant to recessive offspring appears, the unknown parent was….

Heterozygous (Yy)

What is the bottleneck effect

Occurs when a large population suffeers a drastic reduction in size due to an event. The surviving small population loses many alleles, drastically reducing genetic diversity.

What is the founder effect?

Occurs when a small group of indivudals colonize a new location, establishing a new population whose gene pool reflects only the alleles of the founders rather than the original source population.

What is genetic drift?

Random chance events that cause allele frequencies to change unpredictably from generation to generation. Drift is strongest in small populations and does not lead to adaptation.

What is positive assortative mating

Inbreeding, individuals mate with similar phenotypes.

What does inbreeding do

It creates an increase in homozygosity and a decrease in heterozygotes

What is negative assorative mating

Outbreeding, individuals mate withy distinctly different phenotypes, maintaines heterozygosity.

What is gene flow

The movement of individuals and their genetic material into or out of a population. Migration introduces or removes alleles, changing local allele freuqencies and reducing genetic differences between populations.