Exam 20: Mechanisms of Evolution

The graph shows the range of variation among population members for a trait determined by multiple genes. If this population were subject to stabilizing selection for several generations, which, if any, of the distributions shown would be most likely to result?

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. Is strain C accumulating mutations at roughly a linear rate? If yes, what is the rate? If no, is the accumulation faster or slower than linear?

In a population of hamsters, some individuals have the nucleotide G at a locus and some have the nucleotide A.Stating that an individual has copies of both G and A characterizes that individual's _______, and that individual is a _______.

A normally asexual lineage experiences sexual reproduction, and as a result the amount of genetic variation increases and deleterious mutations are purged from the lineage.This purging is a reversal of

Male whitetail deer produce antlers every year and then shed them after the breeding season.Discuss the trade-offs in this cycle.

Which mode(s) of selection result(s) in a decrease in variation?

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 stabilizing selection?

Suppose in a population of 250,000 mice the mutation rate per nucleotide for a genetic locus is 4 × 10^-8.The locus contains 1,500 nucleotides.How many new mutations should we expect at this locus in each generation?

In a haploid bacterium, 720 of 900 individuals have the c1 allele.What is the frequency of the c1allele?

If the frequency of one allele at a locus with two alleles is 0.73, the frequency of the other allele must be _______.

Suppose variants at a single locus affect wing length in a species of crickets, with homozygotes for the L allele having long wings, homozygotes for the l allele having short wings, and heterozygotes having wings of intermediate length.In one population of 600 individuals, 400 have long wings, 160 have intermediate-length wings, and 40 have short wings.Is there an excess or a deficiency of heterozygotes in the population with respect to Hardy-Weinberg equilibrium? By how many individuals?

Height in humans is influenced by numerous loci and has a relatively smooth distribution.It is thus a _______ or _______ trait.

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 fitness aspects (survival, etc.) are independent of size, this population is most likely experiencing _______ selection.

In Mendel's peas, tall and short plant variants resulted from differences at a single genetic locus, with tall being dominant to short.The height of the plant is called its

A cricket has a diploid genome of 1.2 billion bp.Assume that there are about 200,000 individuals in the population and that the mutation rate is 1 per 100 million bp.About how many new mutations will occur in each generation of the population of crickets?

Refer to the figure. Suppose an experiment like that of Malte Andersson were repeated in a different population of widowbirds, and the results shown were obtained.What inferences would you draw from these results? Would sexual selection still be operating?

The differential contribution of offspring to the next generation by various genetic types belonging to the original population is known as _______.

If there is only one allele at a locus in a particular population, that allele is said to be fixed and the locus is _______.

In several species of insects, males with large testes often have better mating success but take longer to develop than those with small testes.Such a pattern is an example of a(n) _______.

The observation that females of a species of beetles prefer to mate with males with relatively rare color patterns would be an illustration of