Exam 20: Mechanisms of Evolution

A population of beavers has 135 individuals that are homozygous for one allele, 230 that are heterozygous, and 135 that are homozygous for the other allele.Compared with Hardy-Weinberg expectations, this population has _______ too _____ heterozygotes.

In a population of sea otters, the frequency of the alpha allele at locus Y6 is 0.8.If the population has 400 individuals, what is the expected number of alpha alleles in the population?

Allele frequencies can be used to measure the _______ of a Mendelian population, whereas _______ show(s) how it is/they are distributed among the population's members.

Studies of enzyme genotypes and flight in Colias butterflies showed that

The survivorship of individuals from three different populations of a beetle species has been assayed and is presented in the table. TT, TC, and CC represent genotypes at a locus that affects survival.Assuming that genotypes at this locus have no other effects on fitness, in which population(s) would we expect variation to be maintained by selection?

What was Darwin's explanation for the evolution of bright colors and other apparently useless (and potentially deleterious) but conspicuous characters in males of many species?

Small populations are _______ likely to be near Hardy-Weinberg equilibrium than large populations, because genetic drift is _______ important in small populations.

The size of a particular appendage in many populations of beetles is determined by alleles at many genetic loci and is largely unaffected by selection.Initially, many populations start with about the same average size of the appendage.Assuming that genetic drift is the only evolutionary process operating, we would expect that over the course of many generations, the average size of the appendage would _______ and that there would be _______ difference in the size of the appendage among the different populations.

Alleles are

The numbers of fledged young from female robins of different sizes were assayed and are presented in the table. Assume that body size is at least partially heritable.Assuming that all other aspects (survival, etc.) are independent of size, this population is most likely experiencing _______ selection, and the variation in the population should _______ over many generations.

In a small, asexual population of rotifers, the average number of mutations in any individual increases steadily in each generation.The most likely mechanism for this is _______.

The numbers of fledged young of female swamp sparrows of different sizes were assayed and are presented in the table. Assume that body size is at least partially heritable.What type of selection is most likely occurring in population A? Assume that all other aspects (survival, etc.) are independent of size.

Warfarin is a popular and potent rodent poison, as well as a blood-thinning medicine.Rats that have one copy of the allele for resistance to warfarin have increased resistance and thus better survival in an environment with warfarin.Rats that are homozygous for this allele are less fit than heterozygotes, even in the presence of warfarin, because they have much higher requirements for vitamin K.Which best describes what occurs in an environment with warfarin?

A population of mice has been monitored for change over several generations.Following are five different bones and the changes to their means and extents of variation. Tibia: Mean increased 0.14 units; variation decreased. Femur: Mean increased 0.08 units; variation increased. Ulna: Mean did not change; variation increased. Clavicle: Mean did not change; variation decreased. Radius: Mean decreased 0.12 units; variation decreased. Which is most likely to be under diversifying selection?

The FY3 gene plays a role in immune responses in flies.In one population, there are two alleles, and the frequency of one allele is 0.6.If the population is at Hardy-Weinberg equilibrium, what is the frequency of heterozygotes?

Assuming there are only two alleles at a given locus, if the frequency of one allele is 0.3, what is the frequency of the other allele?

In a species of beetles, males that have large horns are better able to fight off other males for access to females.This is an example of _______ selection.

Disruptive selection for body size would most likely occur when

The presence of pathogens will tend to _______ the evolution of sexual reproduction because _______.

Although Darwin's voyage aboard the HMS Beagle took him around the world, most of his observations on natural history were made on the continent of _______ and its nearby islands.