Weekly Quiz 5 Macroevolution

Heterozygote advantage should be most closely linked to which of the following? a)sexual selection b) stabilizing selection c) random selection d) directional selection e) disruptive selection

B) stabilizing selection

Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it? allopatric speciation, ecological isolation sympatric speciation, habitat differentiation allopatric speciation, behavioral isolation sympatric speciation, sexual selection sympatric speciation, allopolyploidy

B) sympatric speciation; habitat differentiation

(27 26.4) Natural selection for traits that keep distinct populations from reproducing with each other is called reinforcement. When is reinforcement beneficial? a) when populations would otherwise fuse over time b) when hybrids have lower fitness than either parent population c) when prezygotic isolating mechanisms are in place d) when one population could be overwhelmed by the other e) reinforcement is beneficial under all of the above conditions

B) when hybrids have lower fitness than either parent population

Which of the following statements about speciation is correct? a) The goal of natural selection is speciation. b) When reunited, two allopatric populations will not interbreed. c) Natural selection chooses the reproductive barriers for populations. d) Prezygotic reproductive barriers usually evolve before postzygotic barriers. e) Speciation is a basis for understanding macroevolution.

E) Speciation is a basis for understanding macroevolution

27 26.4) The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information? a) Postzygotic isolation exists between the two frog species. b) Prezygotic isolation exists between the two frog species. c) These two species are likely in the process of fusing back into one species. d) The hybrids form a separate species under the biological species concept.

a) Postzygotic isolation exists between the two frog species.

(27 26.1) Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact? a) A prezygotic isolating mechanism b) A postzygotic isolating mechanism c) All of the above

a) Prezygotic isolating mechanism

Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate? a) the postzygotic barrier called hybrid inviability b) the postzygotic barrier called hybrid breakdown c) the prezygotic barrier called hybrid sterility d) gametic isolation e) adaptation

a) the postzygotic barrier called hybrid inviability

(25 25.2) Researchers (Helle et al., 2004) analyzed rates of twin births in the Sami population of Northern Scandinavia during the eighteenth and nineteenth centuries. They found that (1) a baby born from a singleton pregnancy was more likely to survive to adulthood than a baby born from a twin pregnancy, and (2) the average number of offspring raised to adulthood was higher for women who had twins than for those who never had twins. These data suggest that in this population, human twinning rate was ________. a) under direction selection. b) under stabilizing selection. c) under disruptive selection. d) under sexual selection. e) undergoing genetic drift.

a) under direction selection. _______________ Notes: Directional Selection = one extreme trait is favored Stabilizing Selection = against both extremes Disruptive selection = Selection against the mean Genetic Drift (founder effect or bottleneck) = change in allele frequency due to a chance event

Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this? a) artificial selection b) directional selection c) stabilizing selection d) disruptive selection e) sexual selection

b) Directional selection

(27 26.1,) Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? a) They must have strong prezygotic or postzygotic isolating mechanisms in order to spend winter in such close proximity. b) The two species do not breed in the same area, so they are reproductively isolated by allopatry. c) One of the species is probably polyploid, so they are reproductively isolated by genetic incompatibility. d) Reinforcement must be occurring when they winter together.

b) The two species do not breed in the same area, so they are reproductively isolated by allopatry. ----------- Notes: Prezgotic Isolation = a mechanism that prevents the fertilization of eggs (Behavioral/Ethological isolation, habit isolation, mechanical isolation, temporal/seasonal isolation, gamete isolation) Postzygotic Isolation = a mechanism tgat prevents the formation of fertile offspring (Hybrid invialibity/Zygote Mortality, hybrid breakdown, gametic mortality and hyrbid sterility) Allopatry = allopatric species or populations are those that do not have overlapping geographic ranges Reinforcement = can occur as follows: When two populations which have been kept apart, come back into contact, the reproductive isolation between them might be complete or incomplete.

(27 26.2,) Which of the following does not tend to promote speciation? a) the founder effect b) gene flow c) natural selection d) polyploidy

b) gene flow

(25 25.6) Male turkeys have a snood, which is a flap of skin that hangs across their beak. Snood length is negatively correlated with parasite load (e.g., males with longer snoods have fewer parasites), and females prefer to mate with long-snooded males. This is an example of ________. the fundamental asymmetry of sex. sexual selection via female choice. sexual selection via male-male competition. a genetic marker.

b) sexual selection via female choice

In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population? a) disruptive selection b) directional selection c) stabilizing selection d) sexual selection e) No selection would operate because the population is in Hardy-Weinberg equilibrium.

b. directional selection

(27 26.4) Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related tree frogs in South America. If reinforcement of prezygotic isolation is occurring, what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry? a) Calls would be about the same in both areas. b) Calls would be more similar in areas of sympatry. c) Calls would be more different in areas of sympatry. d) There is not enough information to decide what is happening.

c) Calls would be more different in areas of sympatry

(25 25.2) Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length. Fish caught in open water tend to have longer gill rakers and eat different foods than do those caught in shallower water. 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 middle and shallow water around the sides) with a high density of these fish? a) Directional selection b) Stabilizing selection c) Disruptive selection d) Sexual selection e) No selection

c) Disruptive selection

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (i.e., they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following should least likely be observed in the algae-eater population over the course of many generations? a) Selection for drab coloration of the algae-eaters b) Selection for nocturnal algae-eaters (active only at night) c) Selection for larger female algae-eaters, bearing broods composed of more, and larger, young d) Selection for algae-eaters that become sexually mature at smaller overall body sizes e) Selection for algae-eaters that are faster swimmers

c) Selection for larger female algae-eaters, bearing broods composed of more, and larger, young

(25 25.2) A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness. She hypothesizes that the population is experiencing ________. a) directional selection. b) stabilizing selection. c) disruptive selection. d) sexual selection. e) genetic drift.

c) disruptive selection

A defining characteristic of allopatric speciation is a) the appearance of new species in the midst of old ones. b) asexually reproducing populations. c) geographic isolation. d) artificial selection. e) large populations.

c) geographic isolation

Male satin bowerbirds adorn structures that they build, called "bowers," with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them. The evolution of this male behavior is due to a) frequency-dependent selection. b) artificial selection. c) sexual selection. d) natural selection. e) disruptive selection.

c. sexual selection

(27 26.2) House finches were found only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. If the two forms were unable to interbreed when their expanding ranges meet, what would this situation illustrate? a) vicariance b) allopolyploidy c) autopolyploidy d) allopatric speciation e) sympatric speciation

d) allopatric speciation

A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are relatively rare. Which of the following terms best describes this? a) artificial selection b) directional selection c) stabilizing selection d) disruptive selection e) sexual selection

d) disruptive selection

(25 25.3) 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? a) Population bottleneck and Hardy-Weinberg equilibrium b) Heterozygote advantage and stabilizing selection c) Sexual selection and inbreeding depression d) Mutation and natural selection e) Founder effect and genetic drift

e) Founder effect and genetic drift

(27 26.2) Which of the following describes the most likely order of events in speciation? a) genetic drift, genetic isolation, divergence b) genetic isolation, divergence, genetic drift c) divergence, genetic drift, genetic isolation d) divergence, genetic isolation, genetic drift e) genetic isolation, genetic drift, divergence

e) genetic isolation, genetic drift, divergence