Question 1

The number of cichlid species in Lake Victoria is declining, in part because of predation by Nile perch. Which of the following factors is also likely to contribute to the decline in the number of cichlid species in Lake Victoria?

Accepted Answer

A)  reinforcement of isolating mechanisms 
B)  fusion of species 
C)  stability of species 
D)  development of polyploidy

Question 2

Lions and tigers sometimes breed in zoos, but hybrids have not been seen in nature, nor can the hybrids in zoos reproduce well. Which of the following statements is the best conclusion that can be derived from this information?

Accepted Answer

A)  The two species will eventually fuse. 
B)  They are not actually different species. 
C)  Scientists should look more closely for hybrid zones between the species. 
D)  Breeding in zoos is most likely the effect of isolation from available, appropriate mates.

Question 3

Which of the following methods is most likely to lead to the production of two species from one ancestral species?

Accepted Answer

A)  sympatrically, by a point mutation affecting morphology or behavior 
B)  sympatrically, due to extensive inbreeding 
C)  allopatrically, due to extensive inbreeding 
D)  allopatrically, after the ancestral species has split into two populations

Question 4

Which of the following statements best describes a limitation of the biological species concept?

Accepted Answer

A)  The biological species concept cannot be applied to fossils because the biological species concept uses reproductive isolation to define species. 
B)  The biological species concept cannot be applied to haploid species because the biological species concept delineates species by the presence of gene flow between species. 
C)  The biological species concept cannot be applied to polyploid species because the biological species concept separates species by the absence of gene flow between them. 
D)  The biological species concept cannot be applied to sexual species because the biological species concept separates species by the absence of gene flow between species.

Question 5

Two species of tree frogs that live sympatrically in the eastern United States differ in ploidy: Hyla chrysoscelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first?

Accepted Answer

A)  polyploidy 
B)  difference in breeding seasons 
C)  habitat differentiation 
D)  female preference for male mating calls

Question 6

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp, 15 species on the Pacific side and 15 different species on the Atlantic side. Species live at different water depths. Morphological and genetic data show that Atlantic and Pacific species that live at similar depths are sister species. Geological evidence indicates that the Isthmus of Panama started rising about 10 million years ago and the oceans were completely separated by the isthmus about 3 million years ago. Which of the following statements would best explain why the shallow-water sister species are more similar to each other than are the deeper-water species?

Accepted Answer

A)  The shallow-water sister species have been geographically isolated from each other for a shorter time than the deep-water sister species have been. 
B)  Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deep-water shrimp. 
C)  The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp. 
D)  Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.

Question 7

House finches (birds) occurred 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. Which of the following terms best describes the process that had occurred if the two forms did not interbreed when their expanding ranges met?

Accepted Answer

A)  prezygotic isolation 
B)  reinforcement 
C)  allopatric speciation 
D)  sympatric speciation

Question 8

Which of the following organisms would be LEAST able to cross a geographic barrier of water that could lead to allopatric speciation?

Accepted Answer

A)  birds 
B)  plants with wind-dispersed pollen 
C)  small rodents 
D)  mountain lions

Question 9

Which of the following statements best describes unity within a species?

Accepted Answer

A)  Members of a given species can be distinguished by similarity in body shape and other structural features. 
B)  Members of a given species have the potential to interbreed in nature and produce viable, fertile offspring. 
C)  A species is described in terms of its interaction with living and non-living environment. 
D)  The DNA sequence lacks similarities among individuals.

Question 10

Which of the following statements correctly describes a change that must occur for a new species to arise?

Accepted Answer

A)  The number of chromosomes in the gene pool must change. 
B)  Changes to centromere location or chromosome size must occur. 
C)  Large numbers of genes that affect numerous phenotypic traits must change. 
D)  At least one gene, affecting one reproductive barrier, must change.

Question 11

The following question is based on information from Kondo Y. and Kashiwagi A., Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs, Journal of Herpetology 38(3):381−92 (2004).
Two researchers experimentally formed tetraploid frogs by fertilizing diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they allowed the tetraploid frogs to mate with each other, most of the offspring that survived to maturity were tetraploid, with chromosome sets of both diploid parent species. Based on these results, if this type of tetraploid formed in the wild, what would be the most likely result?

Accepted Answer

A)  The two parent species would interbreed and fuse into one species. 
B)  The two parent species would recognize each other as mates. 
C)  The tetraploids would be reproductively isolated from both parent species. 
D)  The tetraploids would invade the habitats of both parental species and cause them to go extinct.

Question 12

The diagram represents the splitting of one population into two separate lineages that become more different over time (the distance between the two lines represents the amount of difference between the two lineages). Which of the following scenarios is most likely result in the patterns shown in the diagram?

Accepted Answer

A)  a glacier that retreats northward and allows contact between eastern and western populations 
B)  an earthquake that pushes debris into the middle of a lake and makes two unconnected lakes 
C)  erosion of a mountain that separated two closely related populations 
D)  building of a canal by people to connect two rivers

Question 13

According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that ________.

Accepted Answer

A)  the species is now extinct 
B)  speciation occurred in one generation 
C)  speciation occurred rapidly in geologic time 
D)  the species will consequently have a relatively short existence compared with other species

Question 14

A team of scientists is trying to understand the evolutionary history of three species of grasses. They hypothesize that Species T is a descendent of a hybrid between Species R and Species S. Which of the following experimental approaches would best help elucidate the evolutionary history of these three species?

Accepted Answer

A)  Hybridize Species R and S; plant the hybrid offspring in environmental conditions similar to those of Species R; follow the morphological and genetic changes in the offspring of the hybrids; and compare any observed changes to Species R. 
B)  Hybridize Species R and S; plant the hybrid offspring in environmental conditions resembling those of Species R, S, and T; follow morphological and genetic changes in the offspring of the hybrids; and compare the observed changes to Species T. 
C)  Sequence the DNA of all three species and determine which alleles are unique to each species. 
D)  Hybridize Species R and S; induce tetraploidy in the hybrids; and compare the hybrids to Species T.

Question 15

A small number of birds arrive on an island from a neighboring larger island. This small population begins to adapt to the new food plants available on the island, and their beaks begin to change. About twice a year, one or two more birds from the neighboring island arrive. Which of the following effects is most likely to result from the immigration?

Accepted Answer

A)  an increase in the speed of speciation 
B)  an increase in birds' adaptation to the new food plants 
C)  a decrease in birds' adaptation to the new food plants 
D)  another round of incipient speciation

Question 16

Two juniper trees (Juniperus scopulorum and J. monosperma) have overlapping geographic ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. Which of the following isolating mechanisms keeps the two species separate?

Accepted Answer

A)  habitat isolation 
B)  temporal isolation 
C)  gametic isolation 
D)  behavioral isolation

Question 17

Lions and tigers sometimes breed in zoos, but hybrids have not been seen in nature and even in zoos they do not reproduce well. Which of the following statements is the best conclusion that can be derived from this information?

Accepted Answer

A)  The biological species concept is invalid because hybrids can be formed. 
B)  Lions and tigers are not actually different species because they can produce viable offspring in captivity. 
C)  The morphological or ecological species concepts must be used rather than the biological species concept because there could be gene flow between the species in nature. 
D)  The biological species concept can be applied because species are, in part, defined by the inability to produce viable, fertile offspring with other species.

Question 18

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, species X and species Y, overwinter together in mixed flocks in Costa Rica. In spring, species X goes to the east coast of North America, and species Y goes to the west coast. Which of the following factors most likely keeps these species separate?

Accepted Answer

A)  strong postzygotic isolating mechanisms in the winter 
B)  strong prezygotic isolating mechanisms in the winter 
C)  the two species reproduce in different geographic areas 
D)  reinforcement of isolating mechanisms must be occurring in the spring

Question 19

Which of the following statements about the punctuated and gradual models of speciation is most accurate?

Accepted Answer

A)  Although speciation can occur rapidly or gradually, the fossil record is not always detailed enough to determine how rapidly a particular speciation event proceeded. 
B)  The fossil record can only determine if the punctuated model is relevant or not to a particular speciation event. 
C)  Genetic differences can only determine if the gradual model is relevant or not to a particular speciation event. 
D)  The fossil record can be used to determine which speciation model best explains a particular speciation event.

Question 20

Which of the following statements best describes the difference between geographic isolation and habitat differentiation (isolation)?

Accepted Answer

A)  relative location of two populations as speciation occurs 
B)  speed (tempo) at which two populations undergo speciation 
C)  amount of genetic variation that occurs among two gene pools as speciation occurs 
D)  identity of the kingdom or domain in which these phenomena occur

Exam 24: Species and Speciation