Genetic Drift and Population Genetics

Flashcards reviewing concepts of genetic drift, effective population size, and gene flow.

What does h² = 1.0 indicate in population genetics?

High heritability within a corn population.

What was found in studies of post WWII children raised in Europe with African-American US soldiers as fathers?

No significant difference in IQ scores compared to other children.

What factors are being ignored when isolating drift?

Selection and mutation.

Define genetic drift.

Random change in allele frequencies in populations.

Besides natural selection, what other process significantly affects allele frequencies?

Genetic drift.

How does genetic drift differ from natural selection in terms of allele frequency change?

Genetic drift changes allele frequencies randomly, while natural selection changes them deterministically.

What are the two possible outcomes for an allele in a population affected by genetic drift over time?

Fixation or extinction.

Even though genetic drift is random, what kind of predictions can be made?

Probabilistic predictions about allele fixation or loss.

What happens to allele frequencies in isolated populations with the same starting allele frequencies?

They diverge, with some alleles becoming fixed in some populations and lost in others.

What does genetic drift cause in terms of heterozygosity (H)?

It decreases heterozygosity.

What is the average frequency of a new mutation?

1 ÷ 2N

For new mutations that become fixed, what is the average time to fixation?

4N generations.

How does gene flow affect populations?

It homogenizes them (keeps them the same).

What is 'Ne' referring to?

Effective Population Size

What factors influence effective population size (Ne)?

Overlap of generations, sex ratio, small breeding groups, variable fertility, and population size fluctuation (bottlenecks).

Explain why unequal sex ratio may affect frequency of A1.

Because next gen. frequency of A1 could be > 0.4 when compared to A2.

What impact does a bottleneck have on population size?

reduce population size.