Multiple Choice
1. Genetic drift is likely to be seen in a population
a) that has a hight migration rate
b) that has a low mutation rate
c) in which natural selection is occuring
d) that is very small
e) for which environmental condidtions are changing

2. Gene flow often results in
a) populations that move to better environments
b) an increase in sampling error in the formation of the next generation
c) adaptive microevolution
d) a decrease in allele frequencies
e) a reduction of the allele frequency difference between populations

3. Sexual selection will
a) select for traits that enhance an individual's chance of mating
b) increase the size of individuals
c) result in individuals better adapted to the environment
d) result in stabilizing selection

Short Answer (or long answer)
1. Summarize in your own words Darwin's theory of natural selection as the mechanism of evolution. (K/U)
2. How are speciation and microevolution different?

Long Answer
1. The evolution of Drug-Resistance HIV. Within a few weeks of treatment with drug X, a patient's HIV population consists entirely of X-resistant HIV. Explain how this rapid evolution of drug resistance is an example of natural selection. (A)

Multiple Choice
1. d
2. e
3. a

Short Answer
1. The excessive production of offspring sets up the struggle for existence; only a small proportion can live to leave offspring of their own. Natural selection is the differential reproductive success of individuals within a population that are best suited to the environment, which leads over generations to greater adaptation of populations of organisms to their environment.
2. Speciation, by which a new species evolves from a parent species, is part of macroevolution and the increase in biological diversity. Microevolution is the process by which changes occur within the gene pool of a population as a result of either chance events or natural selection. If the makeup of the gene pool changes enough, microevolution may lead to speciation

Long Answer
1. Treatment with the drug X prevents most HIV from reproducing. X-resistant HIV are still able to reproduce. Those that don't reproduce die and those that do populate the host. Eventually this results in 100% of the HIV in the host being X-resistant. Because viruses have such a short life span we can see this as an example of how organisms evolve to survive in their habitats over time,