Exam 10: Natural Selection: Empirical Studies in the Wild

Several studies have revealed that the Eda gene fulfills the three necessary conditions for evolution by selection. Which is not one of these conditions?

Which of the following was necessary for the evolution of beak size on Daphne Major?

Abrahamson and Weis did an experiment in which they compared the gall sizes produced on goldenrod clones by different families of gallflies. Why did the researchers use plant clones and compare gall sizes between gallfly families?

You learned how freshwater stickleback populations have lost their body armor through positive selection of a low-armor Eda allele, which is found at low frequency in marine populations. Draw (a) a phylogenetic tree that would support the hypothesis that the low-armor phenotype arose once and then spread throughout freshwater populations and (b) a phylogenetic tree that would support the hypothesis that the phenotype arose independently multiple times in freshwater populations.

What did the Grants conclude about how selection acts on the medium ground finches from their long-term study of the birds on Daphne Major?

If a population of gallflies occurred in an area where birds were present but parasitoid wasps were absent, which type of selection is most likely to affect gall size?

There are as many as 18 species of Darwin's finches that have adapted to different feeding opportunities on the Galápagos islands. The Grants studied the medium ground finch (Geospiza fortis), which feeds primarily on

The Eda gene, which regulates growth of lateral armor plates in stickleback fishes,

In 1977, before the drought on Daphne Major, the average beak depth in the finch population was 9.2 mm. Finches that bred successfully during the drought had an average beak depth of 9.7 mm. The difference between these values represents

What condition would increase the chances of a particular trait evolving by natural selection in response to a change in the environment?

The graph below shows the effect of hunting imposed on horn length in bighorn sheep populations. What type of selection does it show?

Compare the types of selection seen in medium ground finch beak size in the Galápagos Islands after the drought of 1977, in Australian snake gape width after the introduction of the cane toad, and in gall size produced by gallflies after selection by predatory birds and parasitoid wasps. For each scenario, draw a figure illustrating the type of selection acting on the population (draw the distribution of phenotypes in the population before and after selection). Indicate whether the selection is directional, stabilizing, or disruptive.

Which of the following statements is/are true regarding oldfield mice on Florida's Atlantic Coast and Gulf Coast? i. Light-colored mice on the Atlantic Coast lack the Gulf Coast alleles of Mc1r. Ii. Light-colored mice on the Atlantic Coast share a common ancestor with Gulf Coast mice. Iii. Light-colored mice evolved independently in the two locations.

Describe how natural selection could have led to a decrease in gape width of native Australian snakes since the introduction of toxic cane toads.

Which of the following is not a gene identified in the evolution of maize morphology from a teosinte ancestor?

The intermediate gall sizes produced by gallflies are a result of i. predatory birds selecting against large galls. Ii) parasitoid wasps selecting against large galls. Iii) parasitoid wasps selecting against small galls. Iv) predatory birds selecting against small galls.

You learned how freshwater stickleback populations have lost their body armor through positive selection of a low-armor Eda allele, which is found at low frequency in marine populations. How could you determine whether the low-armor phenotype arose once and spread throughout freshwater populations, or whether the allele was selected for independently multiple times?

Describe how Peter and Rosemary Grant demonstrated the following components, each of which is necessary to demonstrate evolution by natural selection: variation in the population, heritability, and differential reproductive success linked to variation.

Natural selection favors gallflies that produce intermediate gall sizes. This is an example of

Which of the following would not have been an advantage for the Grants when studying natural selection in the wild on Daphne Major?