Exam 7: Evolution and Adaptation

Which of the following is a component of macroevolution?

Explain how a diversity of habitats combined with natural selection can lead to sympatric speciation. Provide an example.

You conduct an experiment in which you raise six replicated lines of fruit flies for eight generations. You keep population size constant at 20 adults per generation. You are interested in a gene, bw, that affects eye colour. This gene has two alleles, bw-1 and bw-2. You start each replicated line with the frequency of the bw-1 allele at 50%. Do the data in the graph better match the prediction for the bw alleles evolving by genetic drift or by directional selection? Be sure to define directional selection and genetic drift and describe the prediction of both hypotheses.

The four plots in the figure show possible relationships between the survival and beak length in an island population of birds. Which plot is an example of disruptive selection?

Evolution by artificial selection is similar to evolution by natural selection because I. both require traits to be heritable. II. both incorporate founder effects. III. both generate differences in fitness between individuals.

Darwin supported his argument for evolution by natural selection with the observation that artificial selection caused large changes in a short period because

If a population of butterflies is under strong natural selection favouring large wings but there is no genetic variation for wing size, what do we expect to occur in the next generation?

A small species of fly lays its eggs in plant stems. The developing fly larvae cause a gall, or large round structure, to form in the stem. Genetic differences among flies cause variation in the size of the galls they produce. Both birds and wasps feed on the larvae in the galls. The proportions of small, medium, and large galls able to survive attacks by either birds or wasps are shown in the table. If a population of flies lives in a field with equal abundance of birds and wasps, will gall size be by directional, stabilizing, or disruptive selection? Explain your answer.

Many genetic diseases have severe or lethal effects in the homozygous form, yet alleles for these diseases are not entirely removed by natural selection. Explain how dominance relationships among alleles allow deleterious mutations to remain in a population.

For mutations that enter a population of a diploid organism, which type of mutation is most likely to be affected by natural selection when it first appears?

What process creates new alleles in a population?

A trait that is determined by multiple genes is referred to as

Consider a gene that affects number of seeds in a plant. This gene has two alleles, G and G. If GG plants produce 50 seeds, Gg plants produce 50 seeds, and gg plants produce 25 seeds, how would we describe the effect of these alleles?

Use the following figure to answer questions 46 and 47. -Based on the phylogeny in the figure, which group is most closely related to the reptiles?

Which of the following is a necessary component of allopatric speciation?

The drug chloroquine has been widely used to treat the human parasite malaria. Mutations in the malaria gene pfcrt confer resistance to chloroquine. In some countries, more than 90% of malaria parasites had the pfcrt resistance alleles. When these countries stopped using chloroquine, the frequency of the pfcrt resistance alleles rapidly declined. Provide an evolutionary explanation for the decline in pfcrt resistance alleles after chloroquine was discontinued.

Describe the difference between synonymous and nonsynonymous mutation. Which type is more likely to be affected by natural selection, and why?

Which of the following types of allele would we expect to have the lowest frequency in a population?

An evolutionary novel trait that allows a species to use new niches and undergo a high rate of speciation is

Different forms of a particular gene are known as