Exam 25: Population and Evolutionary Genetics

Give a brief definition of the term genetic equilibrium.

Cytochrome c is a respiratory pigment found in the mitochondria of eukaryotes. Compared with some other proteins, it has changed very slowly over long periods of time. Why?

Genetic drift is primarily associated with relatively small breeding populations.

In the case of complete dominance in a population in equilibrium, we cannot tell which individuals are homozygous dominants and which are heterozygous, but by knowing the frequency of the homozygous recessives, we can estimate the frequency of homozygous dominant and heterozygous genotypes.

One of the Hardy-Weinberg assumptions states that the population is infinitely large. What influence might a small population size have on a Hardy-Weinberg equilibrium?

Assuming that p = 0.3 for a population in Hardy-Weinberg equilibrium, what would be the expected frequency of heterozygotes for the involved allelic pair?

In a population that meets the Hardy-Weinberg equilibrium assumptions, 81% of the individuals are homozygous for a recessive allele. What percentage of the individuals would be expected to be heterozygous for this locus in the next generation?

In directional selection, both phenotypic extremes are equally selected against.

A number of mechanisms operate to maintain genetic diversity in a population. Why is such diversity favored?

Which term is given to the measure of the proportion of offspring that a particular phenotype will contribute to the next generation?

Mutation and migration introduce new alleles into populations. What is the most likely principal force that will shift allelic frequencies within large populations?

Provide a general definition for the term speciation.

Why is mitochondrial DNA often used in construction of phylogenetic trees?

Suppose that a given gene undergoes a mutation to a dominant allele such that 2 out of 100,000 offspring exhibit the new mutant phenotype. Assuming that these offspring are heterozygous, what is the mutation rate for the gene?

In zoo animals, inbreeding often occurs because of a lack of a sufficient pool of breeding individuals. Under such conditions, what two characteristics are often exhibited among inbred organisms?

Natural selection occurs when there is nonrandom elimination of genotypes from a population due to differences in viability or reproductive success.

What type of evolutionary information can be gained by examining the amino acid sequence of a protein such as cytochrome c?

Present a rationale for using DNA sequence polymorphisms as an index of genetic diversity. Is genetic diversity directly proportional to evolutionary (phylogenetic) diversity?

What is the term given to a group of individuals belonging to the same species that live in a defined geographic area that actually or potentially interbreed?

List at least five of the assumptions that pertain to a population in a Hardy-Weinberg equilibrium.