Genetic dift is the random fluctuation in allele frequency between generations.

A large population has a lower chance of significant changes in the gene pool

No sexual selection or competitive advantages

Everyone is equally fit

If the statistics for people who have PKU is 1 in 10000, what percentage of the population carries the gene but not exhibit the disease?

Given $q^2 = 0.0001$,

$q = 0.01$

$p + q = 1$, so $p = 0.99$

$2pq = 2(0.01)(0.99) = 0.0198$

If only 6% of the population displays pale eyes (recessive gene e), what is the frequency of genotype Ee in this population?

Given $q^2 = 0.06$,

$q = \sqrt{0.06}$

$p + q = 1$, so $p = 1 - \sqrt{0.06}$

$2pq = 2(1 - \sqrt{0.06})(0.06) = 0.369 = 36.9\%$

In Drosophila, the allele for normal length wings is dominant over the allele for vestigial wings (vestigial wings are stubby little curls that cannot be used for flight). In a population of 1,000 individuals, 360 show the recessive phenotype. How many individuals would you expect to be homozygous dominant for this trait?

Given $q^2 = \frac{360}{1000} = 0.36$,

$q = \sqrt{0.36} = 0.6$,

$p + q = 1$, so $p = 1 - 0.6 = 0.4$

Therefore, $p^2 = 0.16 = 16\%$

16% of 1000 = 160

For foxes there exists a single gene that controls coat thickness. Allele C confers a thick coat while allele c is a thin coat. In a population of 540 foxes, 49 have thin coats. What are the dominant and recessive allelic frequencies?

Given $q^2 = \frac{49}{540}$

$q = \sqrt{\frac{49}{540}} = 30\%$

$p + q = 1$, so $p = 1 - \sqrt{\frac{49}{540}} = 70\%$

The gene for albinism is known to be a recessive allele. In Michigan, 9 people in a sample of 10,000 were found to have albino phenotypes.

• What is the allele frequency for the dominant pigmentation allele in this population? Given $q^2 = \frac{9}{10000}$, $q = \sqrt{\frac{9}{10000}} = 0.03$ $p = 1 - 0.03 = 0.97$
• How many of the 10000 people in the sample above were expected to be heterozygous for pigmentation? Solve for $2pq$ $2pq = 2(0.97)(0.03) = 0.058$ 5.8% of 10000 = 580

The fossil record can give rise to transitional species.

However, not every organism will leave behind a fossil. Fossils are extremely rare, and sometimes only the partial fossil will be preserved.

• Homologous structures