A geneticist has studied the sequence of a gene in each of three species, A, B, and C. Species A and species B are sister species; species C is more distantly related. The geneticist has calculated the ratio of nonsynonymous (NS) to synonymous (S) nucleotide substitutions in the coding region of the gene in two ways—first, by comparing the gene sequences of species A and C, and second, by comparing the gene sequences of species B and C. The NS:S ratio for the comparison of species B and C is five times greater than it is for the comparison of species A and C. What might this difference in the NS:S ratios suggest?

If a randomly mating population is segregating n selectively neutral alleles of a gene and each allele has the same frequency, what is the frequency of all the homozygotes in the population?

Ribonuclease, a protein that degrades RNA, is $124$ amino acids long. A comparison between the amino acid sequences of cow and rat ribonucleases reveals $40$ differences. What is the average number of amino acid substitutions that have occurred per site in these two evolutionary lineages? If the cow and the rat lineages diverged from a common ancestor $80$ million years ago, what is the rate of ribonuclease evolution?

During the early evolutionary history of the vertebrates, a primordial globin gene was duplicated to form the $\alpha$- and $\beta$-globin genes. The rate of evolution of the polypeptides encoded by these duplicate genes has been estimated to be about $0.9$ amino acid substitutions per site every billion years. By comparing the human $\alpha$- and $\beta$-globins, the average number of amino acid substitutions per site has been estimated to be $0.800$. From this estimate, calculate when the duplication event that produced the $\alpha$- and $\beta$-globin genes must have occurred.

The heme group in hemoglobin is held in place by histidines in the globin polypeptides. All vertebrate globins possess these histidines. Explain this observation in terms of the Neutral Theory of Molecular Evolution.

What was some of the evidence that led Charles Darwin to argue that species change over time?

Compare species richness and species evenness.

The rate law for the following reaction CO + NO2 $\to$ CO2 + NO is rate = k[NO2]^2. Suggest a plausible mechanism for the reaction, given that the unstable species NO3 is an intermediate.

Differentiate between the typological species concept and the phylogenetic species concept.

Suppose that the population dynamics of a species obeys a modified version of the logistic differential equation having the following form: $\frac{d N}{d t}=r\left(1-\frac{N}{K}\right)^{2} N$ where $r \neq 0 \text { and } K>0.$ Show that $\hat{N}=0 \text { and } \hat{N}=K$ are equilibria.

If we compare related rabbit species in desert and Arctic environments, we would expect (a) the desert species to have shorter legs. (b) the Arctic species to be smaller. $(c)$ the desert species to have larger ears. (d) the Arctic species to be the same size as the desert species.

Give examples of species that are likely to be coevolving. Describe how each species influences the evolution of the other species.

Which of the following ionic species could be responsible for hardness in a water supply: $\mathrm{Ca}^{2+}, \mathrm{K}^{+}, \mathrm{Mg}^{2+}, \mathrm{Fe}^{2+}, \mathrm{Na}^{+}$?

Fill in the letter of the choice that best answer the question. Sometimes a species that is introduced to an area grows quickly and crowds out organisms that were already living there. What is this introduced species called? A. native species B. protected species C. invasive species D. beneficial species