Exam 20: Mechanisms of Evolution

If variation at a given locus has no effect on the phenotypes of individuals, which evolutionary process will still occur at that locus?

Suppose that in a group of flies the mutation rate per nucleotide is about 10 per billion, there are 300 million nucleotides in the haploid genome, and the population size is 40 million.In this case, in every generation about _______ new mutations will appear in the population.

Genetically identical roundworms are raised in two different environments.In the warmer environment, the worms are shorter than they are in the cooler one.What can we infer from this observation?

Suppose a population of garter snakes that was initially naive to newts with TTX was placed with such newts.Assuming that the population persisted, over the course of many generations, we would expect the snakes to _______ in TTX resistance and _______ in speed.

Snapping shrimp have evolved very rapid movements in the structures they use to capture prey.These rapid movements, which evolved through natural selection, can be considered a(n) _______, and the process by which they evolved is called _______.

Which statement about garter snakes that are resistant to tetrodotoxin (TTX) is true?

In a population of 200 individuals at Hardy-Weinberg equilibrium, 72 were homozygous recessive for the character of eye color (cc).One hundred individuals from this population died from a fatal disease.If 36 of the survivors are homozygous recessive, how many heterozygous individuals are in the new population?

In a population of 600 moose, 30 percent of the individuals are homozygous for an allele and 45 percent are heterozygotes.How many copies of the allele are present in the population?

Several populations of copepods are sampled for variation at the G locus.Population A is found to be 30 percent GG, 60 percent Gg, and 10 percent gg.Population B is 62 percent GG, 36 percent Gg, and 2 percent gg.Population C is 30 percent GG, 40 percent Gg, and 30 percent gg.Which of these populations shows a heterozygote deficiency?

Three different alleles (c1, c2, and c3) at the c locus exist in a hypothetical population of juniper trees.If the frequency of c1 is 0.3, what can be said about the frequency of c2?

Refer to the graph showing beak size for a population of a species of Darwin's finches. Draw a graph showing what the resulting population would most likely look like after a generation of strong disruptive selection.

An allele in a population of mockingbirds has a frequency of 0.3.In a population of 600, how many copies of the allele are present?

A population of geese has an allele frequency of 80 percent for one allele of a locus with two alleles.Out of 750 individuals, _______ should be homozygotes for the less common allele if the population is at Hardy-Weinberg equilibrium.

Which statement about genetic drift as an evolutionary factor is true?

A population of swallowtail butterflies has an allele frequency of 60 percent for one allele of a locus with two alleles.Out of 1,500 individuals, ______ should be homozygotes for the more common allele if the population is at Hardy-Weinberg equilibrium.

In many bird species, the number of eggs laid is negatively correlated with the survival of the young.At the extreme of very large clutch sizes, hardly any of the young survive.Clutch size variation is largely due to genetic factors.In light of this, which statement is most likely to be true?

Individual females within a population of horses are tracked over time to examine their reproductive output.The researchers find that females with the smallest and largest body sizes have fewer offspring than females of average body size.Most likely, _______ selection for size is operating.

Selection currently maintains an intermediate body size in a population of salmon.Bears selectively prey on the largest individuals, and smaller individuals produce fewer offspring.Suppose that bears are removed from the area.Most likely, the salmon size will increase because of ______ selection.

The most likely reason that subpopulations often vary genetically from one another is that they

The table lists the frequencies of an allele (A) at a locus and the average fitness of carriers of that allele at each frequency in four haploid populations. The fitness of the other allele (a) is always 0.9, regardless of the frequency of the alleles.In which population can both alleles be maintained?