Exam 13: How Populations Evolve

Which situation is most likely to decrease genetic variation?

________ believed that species are fixed forms that do not change over time while ________ believed that evolution is the refinement of traits that equip organisms to perform successfully in their environments.

After surviving a bottleneck, a population recovers to the point where it consists of as many individuals as it did prior to the bottleneck. Which statement is most likely to apply to this population?

Scenario Over the past 60 years, many amphibian species have experienced significant population declines, and some species have become extinct. Scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. However, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. These global declines suggest widespread problems, including increased ultraviolet radiation, acid rain, and disease. In Switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. -Chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. In some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. If these resistant individuals continue to survive and prosper, new resistant populations might emerge. This would be an example of ________.

The accompanying figure shows what happens in insect populations when crops are sprayed with insecticides. This is an example of ________.

Which anatomical features are homologous?

Scenario Drs. Peter and Rosemary Grant have been conducting observational research studies on finch species on Galápagos Island Daphne Major for over 40 years. The medium ground finch has a relatively small beak and a diet that consists primarily of small seeds. Large-beaked finches are able to eat larger seeds in addition to small ones. These two species successfully co-existed on the island for over 20 years, but two years of severe drought in 2003 and 2004 lead to intense competition between them because food supplies were destroyed in the drought. Numerous birds in both populations died from starvation. Interestingly, the Grants noticed that the smaller-beaked finches did not face the same degree of competitive pressure, because they could more easily eat the smaller seeds that were not being eaten by the larger finches. Only a short time later (2004-2005), the Grants observed that new populations of finches had more birds with smaller beaks than larger ones. As well, finches tended to seek out larger seeds half as often as in preceding years. -The Grants' data suggest that ________.

Which phenomenon (or lack of)will prevent significant genetic drift?

Scenario In order to test the susceptibility of bacteria (if the bacteria are susceptible to being killed)to an antibiotic, a common laboratory test called the Bauer-Kirby Disk Diffusion test is used. First, a petri dish (a shallow, circular, transparent dish with a flat lid)is partially filled with nutrient-enriched agar (a gelatinous material). The nutrients encourage growth of specific bacterial species. The agar is poured as liquid but then typically solidifies to a soft consistency. Once the agar is set, a "lawn" of bacteria is spread such that a thin layer covers the top of the agar. Antibiotics are then applied to the lawn in a small dose, often through small, saturated paper disks. The dish is typically incubated for 24-48 hours and then observed for susceptibility. If the antibiotic is effective, it will kill the bacteria and leave a clear area called the "zone of inhibition" due to inhibited bacterial growth. The area starts at the source of the antibiotic and radiates outward. Scientists measure the diameter of the zone and then compare it to an established "cutoff value" for a zone specific to antibiotic/organism combinations. A large zone of inhibition in comparison to the standard indicates susceptibility while a small or no zone indicates resistance. Consider the following image, and answer the questions that follow: -After 1 year of widely prescribed use, reports surface that bacterial infections disappear for up to 2 weeks after taking the FDA-approved antibiotic but then reappear, sometimes worse than the first time. Which explanation might the FDA use to defend their choice of antibiotic to treat the infection?

Which is NOT a requirement of natural selection?

Which is a component of the fossil record?

Which is a characteristic of a population at Hardy-Weinberg equilibrium?

In the Hardy-Weinberg formula, what does p² represent?

In The Origin of Species, Darwin argued that the mechanism of descent with modification was ________.

While on the Beagle, Darwin's observations suggested that ________ is (are)a better predictor of relationships among organisms than ________.

Scenario Drs. Peter and Rosemary Grant have been conducting observational research studies on finch species on Galápagos Island Daphne Major for over 40 years. The medium ground finch has a relatively small beak and a diet that consists primarily of small seeds. Large-beaked finches are able to eat larger seeds in addition to small ones. These two species successfully co-existed on the island for over 20 years, but two years of severe drought in 2003 and 2004 lead to intense competition between them because food supplies were destroyed in the drought. Numerous birds in both populations died from starvation. Interestingly, the Grants noticed that the smaller-beaked finches did not face the same degree of competitive pressure, because they could more easily eat the smaller seeds that were not being eaten by the larger finches. Only a short time later (2004-2005), the Grants observed that new populations of finches had more birds with smaller beaks than larger ones. As well, finches tended to seek out larger seeds half as often as in preceding years. -In these observational studies, what would have served as a control experiment?

The first basic idea of evolutionary adaptation can be traced back to ________.

In the Hardy-Weinberg formula, what does 2pq represent?

The presence of freckles is due to a dominant allele. Four percent of the individuals in a particular population lack freckles. Use the Hardy-Weinberg formula to calculate the percentage of individuals in this population who are homozygous dominant for freckles.

Disruptive selection can lead to ________.