Exam 20: Mechanisms of Evolution

In Mendel's crosses with peas, seed shape is due to a single allele, and the allele for smooth seeds is dominant to the allele for wrinkled.If 20 percent of a population has the smooth allele, _______ percent of the plants should have wrinkled seeds at Hardy-Weinberg equilibrium.

In a hypothetical population of gazelles, 28 individuals are homozygous for the d2 allele, 72 individuals are heterozygous for the d2 allele, and 100 individuals lack the d2 allele.What is the frequency of the d2 allele?

Suppose males of a bird species have much more colorful plumage than the females and that the intensity of red color varies in males.Which would be the best evidence that intrasexual selection was occurring?

An allele that increases the ability to digest lactose, the sugar in milk, increased in frequency in human populations in which cows were herded.This is an example of _______ selection.

Suppose that in a species of beetle, individuals that are larger than average are good at catching large prey, whereas individuals that are much smaller than average are better at avoiding being preyed on.Individuals with intermediate phenotypes are not good at either task.This is an example of _______ selection.

In scientific terms, the word "_______" refers to a significant body of factual evidence and its applications in a particular field of knowledge.

Which statement about mutations is true?

Sexual recombination

It may be that red hair evolved in Neanderthals and then was introduced into human populations via interbreeding.If this is so, this would be an example of

Under which condition is Hardy-Weinberg equilibrium not applicable?

Male earwigs that are DD at a locus have greater success in mating than those that are Dd or dd.Which type of selection is operating?

Which mode(s) of selection lead(s) to a reduction in variation but no change in the mean?

Suppose a population of flour beetles has 1,000 individuals.Normally the beetles are red; however, this population is polymorphic for a mutant autosomal body color, black, designated by bb.Red is dominant to black, so BB and Bb genotypes result in red beetles.Assume the population is at Hardy-Weinberg equilibrium, with equal frequencies of the two alleles.What would be the expected red and black allele frequencies if 1,000 black individuals migrated into the population?

Three populations of mustard plants are sampled for variation at the F locus.Population A is 20 percent FF, 60 percent Ff, and 20 percent ff.Population B is 63 percent FF, 34 percent Ff, and 3 percent ff.Population C is 35 percent FF, 30 percent Ff, and 35 percent ff.Which population(s) show(s) a heterozygote deficiency?

The graph shows the range of variation among population members for a trait determined by multiple genes. Suppose that there were no genetic component to this trait.If this population were subject to stabilizing selection for several generations, which distributions would be most likely to result? Assume that the environment stayed the same.

A population of marmots has an allele frequency of 80 percent for one allele of a locus with two alleles.Out of 750 individuals, ______ should be heterozygotes if the population is at Hardy-Weinberg equilibrium.

If a change in the nucleotide, from T to G, at the 678th position of a gene sequence has no effect on the phenotype of its bearers, this change is a(n) _______ mutation.

The numbers of fledged young of female song sparrows of different sizes were assayed and are presented in the table. Assume that body size is at least partially heritable.Assume that all other aspects (survival, etc.) are independent of size.What type of selection, if any, is most likely occurring in population C? If selection is operating, what is the most likely effect of this selection on the phenotypic distribution?

Suppose there are three isolated populations of a beetle: population A has had a constant population size of 10,000, population B has had a constant population size of 1,000, and population C has had a constant population size of 100.We would most expect to see an increase in the frequency of deleterious alleles in population _______ due to _______.

In disruptive selection,