6 Evolution and Population Genetics Free Online FlashCards

What does evolution mean in population genetics?

Evolution is a change in allele frequencies in a population across generations.

How do genotype and phenotype differ?

Genotype is an organism’s genetic makeup; phenotype is its observable trait, shaped by genotype and often by the environment.

What is a population’s gene pool?

A gene pool is the collection of all alleles in a population.

When does natural selection change allele frequencies?

Natural selection occurs when heritable differences are associated with differences in reproductive success. Alleles contributing to greater success in a given environment tend to become more common.

What genotype frequencies does Hardy–Weinberg predict?

For two alleles with frequencies $p$ and $q$, $p + q = 1$. Expected genotype frequencies are $p^2$ for AA, $2pq$ for Aa, and $q^2$ for aa.

What is the law of segregation?

The law of segregation states that the two alleles of a gene separate into different gametes during meiosis.

How does linkage affect the inheritance of two genes?

Unlinked genes, or genes far apart on the same chromosome, can assort independently. Nearby genes may be inherited together, though crossing over can recombine them.

What outcomes are expected from an Aa × Aa cross?

The expected genotypes are $\frac{1}{4}$ AA, $\frac{1}{2}$ Aa, and $\frac{1}{4}$ aa. With complete dominance, the expected phenotype ratio is three dominant to one recessive.

What does dominance not tell you about an allele?

Dominance describes how alleles affect a phenotype; it does not mean an allele is more common or more advantageous.

What is mutation’s role in genetic variation?

Mutation creates new genetic variants and is the ultimate source of new alleles. A mutation may be neutral, harmful, or beneficial depending on context.

What is genetic drift, and when is it strongest?

Genetic drift is random change in allele frequency due to chance. Its effects are strongest in small populations.

How do bottlenecks and founder effects differ?

A bottleneck follows a sharp reduction in population size; a founder effect occurs when a new population is established by a small number of individuals.