Exam 1

Darwin and Wallace were the first to propose _____.

natural selection as the mechanism of evolution

A Bigfoot and a chupacabra mate and have offspring that survive. However, these hybrid offspring do not have viable offspring of their own. What type of reproductive barrier is this?

Hybrid infertility

Reinforcement is most likely to occur when _____.

hybrids have lower fitness than either parent population

For a biologist studying a small fish population in the lab, which Hardy-Weinberg condition is easiest to meet?

no gene flow

For biologists studying a large flatworm population in the lab, which Hardy-Weinberg condition is most difficult to meet?

no mutation

The approach to estimating phylogenetic trees is most like the approach of which species concept?

phylogenetic species concept

The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____.

reduced hybrid fertility

Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by _____.

reduced hybrid viability

Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship.

2 → 4 → 1 → 3

Rank the following in order from most general to most specific: 1. gametic isolation 2. reproductive isolating mechanism 3. sperm-egg incompatibility in sea urchins 4. prezygotic isolating mechanism

2, 4, 1, 3

Godzilla and Mothra mate. It's loud and attracts quite a crowd, and the movie is great. However, Mothra (the female involved) never becomes pregnant. What type of reproductive barrier is this?

Gametic isolation

What must be true of any organ described as vestigial?

It must be homologous to some feature in an ancestor.

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to increasingly colder temperatures, would eventually give rise to more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of _____.

Lamarck

Macroevolution is _____.

evolution above the species level

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three million years ago. In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?

A5 and B5

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three million years ago. In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?

B4

A Bigfoot is kidnapped by a human. The human attempts to carry the Bigfoot away for mating purposes. The Bigfoot frantically runs away and escapes the clutches of this amorous human. What type of reproductive barrier is this?

Behavioral

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

Characteristics acquired during an organism's life are generally not passed on through genes.

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering and in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers. But caterpillars that hatch in summer feed on oak leaves and look like oak twigs. How does the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below. In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups (4 environments × 2 diets). Refer to the accompanying figure. Which one of the following is NOT a plausible hypothesis to explain the differences in caterpillar appearance observed in this population?

Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

Starting from the wild mustard Brassica oleracea, breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Therefore, which of the following statements is correct?

In this wild mustard, there is enough heritable variation to permit these different varieties.

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?

None of the insect pests would have genetic variations that resulted in DDT resistance.

Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?

Simple morphologies convey some advantage in most parasites.

Count Dracula is a nocturnal organism. The mermaid queen is a daytime beach dweller. Leaving aside the fact that the Count is dead, what is the reproductive barrier between these two organisms?

Temporal

Which of the following is a fitness trade-off (compromise)?

Turtle shells provide protection but are heavy and burdensome when moving.

How are two different species most likely to evolve from one ancestral species?

allopatrically, after the ancestral species has split into two populations

A hybrid zone is properly defined as _____.

an area where mating occurs between members of two closely related species, producing viable offspring

Given what we know about evolutionary biology, we expect to find the largest number of endemic species in which of the following geological features, which have existed for at least a few million years?

an isolated ocean island in the tropics

Scientific theories _____.

are supported by, and make sense of, many observations

According to the biological species concept, for speciation to occur, _____.

at least one gene, affecting at least one phenotypic trait, must change

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?

bones in the flipper of a whale

Speciation _____.

can involve changes to a single gene

Which of the following is the most predictable outcome of increased gene flow between two populations?

decreased genetic difference between the two populations

Which of the following is the best modern definition of evolution?

descent with modification

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?

disruptive selection

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population?

founder effect and genetic drift

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of _____.

frequency-dependent selection

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake?

genetic bottleneck

In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because _____.

heterozygotes can come about in two ways

In the formula for determining a population's genotype frequencies, the "pq" in the term 2pq is necessary because _____.

heterozygotes have two alleles

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that ____.

island forms are descended from mainland forms

The greatest number of endemic species is expected in environments that are _____.

isolated and show little ecological diversity

Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then _____.

sexual dimorphism was evolving over time in these species

A particular Yorkshire terrier breeder is snooty. He wants to make sure that Rufus, the neighbor mixed-breed dog, never gets near his stable of purse dogs. He surrounds the Yorkies' exercise area with a fence made of cinder block. What type of reproductive barrier is this?

spatial

Catastrophism was Cuvier's attempt to explain the existence of _____.

the fossil record

Soon after the island of Hawaii rose above the sea surface (somewhat less than one million years ago), the evolution of life on this new island should have been most strongly influenced by _____.

the founder effect

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.) Refer to the paragraph about the formation of the Isthmus of Panama. The sister populations on opposite sides of the isthmus are true species under which species concept?

the morpholoogical species, biological species, and phylogenetic species concepts

Which of the following evidence most strongly supports the common origin of all life on Earth? All organisms _____.

use essentially the same genetic code

The questions below refer to the following paragraph. HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR. Which of the following represents the treatment option most likely to avoid the evolution of drug-resistant HIV (assuming no drug interactions or side effects)?

using moderate doses of NA and two different PIs at the same time for several months