On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population?
a) Individuals of the species sometimes reproduce asexually by producing runners.
b) Lava has separated the population into two areas: an upland forest and a lowland marsh.
c) Multiple groups of birds depend on the fruit produced by the plants as a source of food.
d) The plants produce more seeds during warm summers than they do during cool summers.

A scientist is studying a population of lizards with three different color phenotypes. The color phenotype is controlled by a single gene with two alleles: an incompletely dominant allele A and a recessive allele a. The scientist collected data on the color of 100 lizards. The data are shown in the table. RED AA 75
PURPLE Aa 15
BLUE aa 10 To test the hypothesis that the population is at Hardy-Weinberg equilibrium, the scientist performed a chi-square test. Which of the following values is closest to the chi-square value the scientist calculated?
a) 0.1
b) 1.9
c) 18.3
d) 23.1

Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile. Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?
a) Gene flow is prevented because the two species belong to different trophic levels and therefore do not share a food source.
b) Habitat isolation creates a prezygotic barrier between the two species.
c) The males of one species and the females of the other species are fertile at different times.
d) The two species have a different number of chromosomes, resulting in a postzygotic barrier.

Figure 1 compares two models of speciation, A and B. Which of the following best explains how the ecological conditions are likely to be different in the two models?
a) In model A the ecological conditions remain unchanged for long periods of time and then change drastically; in model B the ecological conditions change drastically from generation to generation.
b) In model A the ecological conditions remain unchanged; in model B the ecological conditions change gradually over long periods of time.
c) In model A the ecological conditions are changing drastically from generation to generation; in model B the ecological conditions remain unchanged.
d) In model A the ecological conditions change gradually over a long period of time; in model B the ecological conditions remain unchanged for long periods of time and then change drastically.

Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of moths in the natural population was white in 1962?
a) 2%
b) 4%
c) 8%
d) 20%
e) 64%