Deck 14: Species and Speciation

Question 1

Biologists surveying the bacterial flora of Yellowstone National Park, particularly populations located in the park's famous hot springs, have collected data on habitat characteristics, sequenced the DNA of bacteria from each population, and studied the physical characteristics of the cells. They have also compared what they know about these bacteria to other species already collected and identified from the park. Given this information, which species concept would the researchers be UNABLE to apply?

A) evolutionary species concept
B) biological species concept
C) ecological species concept
D) phylogenetic species concept

Answer 1

B

Question 2

What does the figure illustrate?

A) ploidy changes resulting in reproductive isolation
B) Haldane's rule
C) Dobzhansky-Muller incompatibility
D) reproductive isolation through chromosomal rearrangement

Answer 2

C

Question 3

Which of the following is NOT a prezygotic isolating mechanism?

A) habitat isolation
B) temporal isolation
C) hybrid inviability
D) gametic incompatibility

Answer 3

C

Question 4

Hybrids with a chromosomal rearrangement often have

A) a doubling of chromosomes.
B) superior environmental performance across a cline.
C) dysfunctional gametes.
D) increased fitness relative to the parental generation.

Question 5

The ________ species concept defines a species as a cluster of individuals that occupy a particular niche.

A) phonetic
B) evolutionary
C) biological
D) ecological

Question 6

Host tree specificity of Rhagoletis pomonella reduces gene flow between the apple and hawthorn fly races by 4% to 6% in each generation, as individuals tend to mate with the same fruit preference. This is an example of

A) allopatric speciation.
B) assortative mating.
C) secondary contact.
D) resource competition.

Question 7

Two bird species (in which females are heterogametic and males are homogametic) exhibit postzygotic isolation in that half of the hybrid offspring formed between them are sterile. If Haldane's rule applies here, then the individuals that are sterile are likely to be

A) female.
B) male.
C) young.
D) old.

Question 8

In the phylogeny depicted in the figure, the P species are from the Pacific side and the C species are from the Caribbean side of the Isthmus of Panama. Which of the following is the most likely cause of speciation?

A) sympatric speciation
B) parapatric speciation
C) allopatric speciation via dispersal across the Isthmus of Panama
D) allopatric speciation via isolation when the Isthmus of Panama closed

Question 9

The evolutionary species concept defines a species as

A) a group of populations that have a shared past and will have a shared future on a phylogenetic tree.
B) phenotypically similar individuals or populations.
C) groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.
D) the smallest monophyletic group distinguished by a shared derived character.

Question 10

A small population of a species invades an island where the species is not found. The island population subsequently diverges from the ancestral population and becomes a new species. This is an example of

A) the vicariance model of allopatric speciation.
B) the peripheral isolate model of allopatric speciation.
C) sympatric speciation.
D) parapatric speciation.

Question 11

Resource competition is likely to occur

A) when the same plants produce different seed types.
B) infrequently in sympatric speciation.
C) only in lakes.
D) when diet preferences are a function of differences in a phenotypic trait.

Question 12

Which of the following statements about changes in ploidy is true?

A) It often reduces reproductive isolation.
B) It can result in instantaneous speciation.
C) It causes shell coiling in snails.
D) It is less common in plants than animals.

Question 13

The figure on the left illustrates species boundaries as assigned by the application of the biological species concept, while the figure on the right illustrates species boundaries as the result of the ecological species concept. What is the difference in how these boundaries are delineated when applying these concepts?

A) The biological species concept uses the pattern of gene flow to assign boundaries, while the ecological species concept uses competition.
B) The biological species concept uses shared, derived characters to assign boundaries, while the ecological species concept uses competition.
C) The biological species concept uses competition to assign boundaries, while the ecological species concept uses gene flow.
D) The biological species concept uses polymorphic characters to assign boundaries, while the ecological species concept uses shared, derived characters.

Question 14

How might secondary contact result in a cline?

A) Reproductive character displacement completes the speciation process.
B) Hybrid matings may have low fitness.
C) Reproductive isolation is partially complete and a spatial gradient of hybrids forms.
D) Reproductive isolation is incomplete and the two populations form a single species without spatial variation.

Question 15

Which of the following is NOT a postzygotic isolating mechanism?

A) Male gametes are not transferred to the female gametes.
B) Zygotes die early in embryogenesis.
C) Hybrids are inviable.
D) Hybrids are sterile.

Question 16

A cline is a(n)

A) temporal gradient in the frequency of genotypes and phenotypes.
B) spatial gradient in the frequency of genotypes and phenotypes.
C) area of resource competition.
D) area of assortative mating.

Question 17

Allopatric speciation requires

A) complete geographic isolation.
B) abutting distributions.
C) overlapping distributions.
D) differences in phenology.

Question 18

What is the most common reason for the disappearance of a hybrid zone, resulting in the completion of the speciation process?

A) when hybrids are at a selective disadvantage compared to offspring from within-population matings
B) when hybrids have a selective advantage and replace the parent species
C) when hybrids are found in ring species and no longer mate with the parent species
D) when hybrids mate assortatively

Question 19

In order to determine if individuals from separate populations are indeed distinct species, Drosophila biologists often test to see if individuals from different populations will mate with each other. This is an application of the ________ species concept.

A) evolutionary
B) phenetic
C) phylogenetic
D) biological

Question 20

Which of the following statements describes a challenge of applying the phenetic species concept?

A) construction of a phylogenetic tree that accurately portrays relationships
B) how to weigh the relative importance of the characters used
C) the measurement of gene flow within the population
D) The concept can only be applied to sexually reproducing species.

Question 21

In the graphs shown here, what do the axes represent? Which species concept is illustrated by these graphs?

Question 22

The figure shows the geological history of North and South America and the closing of the Isthmus of Panama. If a single species was distributed throughout the region indicated by the arrow in the left-most panel, and today is found as two separate species, one in the Atlantic Ocean and one in the Pacific, is this allopatric speciation likely to be an example of the vicariance model or the peripheral isolate model of allopatric speciation? Why?

Question 23

How does the evolutionary species concept differ from the phylogenetic species concept?

Question 24

Haldane's rule states that in hybrid offspring, the sex that is heterogametic is the sex observed to be absent, rare, or sterile. Which statement is the most likely explanation for this phenomena?

A) Because the heterogametic sex only has a single copy of each chromosome, effects of a single recessive allele linked to the chromosome will always be expressed and will have a negative effect on that hybrid.
B) Because the heterogametic sex has two copies of each chromosome, effects of a single recessive allele linked to the chromosome will never be expressed and will have a negative effect on that hybrid.
C) Because the homogametic sex only has a single copy of each chromosome, a single recessive allele linked to the chromosome will always be expressed and will have a negative effect on the hybrid parents.
D) Because the heterogametic sex has two copies of each chromosome, a single recessive allele linked to the chromosome will never be expressed and will have a negative effect on the hybrid.

Question 25

Scientists have hypothesized that resource competition may facilitate sympatric speciation. These graphs illustrate two scenarios: graph A illustrates a normal distribution of both beak size and seed size, while graph B illustrates a normal distribution of beak size but a flat distribution of seed size. Which graph illustrates resource competition?

A) Graph A illustrates resource competition; different seed sizes have led to the distribution of different beak sizes, so all birds get approximately the same amount of food.
B) Graph A illustrates resource competition; different beak sizes led to the distribution of different seed sizes, so all birds get approximately the same amount of food.
C) Graph B illustrates resource competition; because there are equal numbers of seeds available across the size range.
D) Graph B illustrates resource competition; because there are more medium-beaked birds, there is more competition for medium-sized seeds.

Question 26

Parapatric speciation and sympatric speciation both describe how populations diverge into separate species without a geographic barrier to dispersal. What distinguishes these two modes of speciation?

A) In parapatric speciation, the populations are adjacent to one another and typically have a hybrid zone between the populations.
B) In sympatric speciation, the populations are adjacent to one another and typically have a hybrid zone between the populations.
C) In parapatric speciation, the populations are not adjacent to each other and do not have a hybrid zone.
D) In sympatric speciation, the populations are not adjacent to each other but do have a hybrid zone.

Question 27

In the course of studying plant communities living on an elevational gradient in Rocky Mountain National Park, researchers observed that a plant species growing in the park appears to actually be three species. The low elevation (LE) species is more clearly distinct from the high elevation (HE) species, but the middle elevation (ME) species has characteristics of both. After taking seeds from all three populations back to their greenhouse for a reproductive study, the researchers discovered that ME plants could not successfully pollinate HE plants, but ME did produce sterile seeds with the LE plants. Which statement best describes the reproductive isolating mechanisms between these populations?

A) ME and HE are isolated through postzygotic mechanisms, while ME and LE are isolated through prezygotic mechanisms.
B) ME and HE are isolated through prezygotic mechanisms, while ME and LE are isolated through postzygotic mechanisms.
C) All three populations appear to be isolated through postzygotic mechanisms.
D) All three populations appear to be isolated through prezygotic mechanisms.

Question 28

Suppose that we find an example of the peripheral isolate model of allopatric speciation in which a species pair results. One species is the progenitor and one is the derivative species. How will these two species differ in geographical distribution, genetic diversity, and allele sharing?

Question 29

In this figure illustrating the ring species concept, which population of salamanders was the most genetically distinct from the other salamander populations?

A) E.e. klauberi
B) E.e. xanthoptica
C) E.e. platensis
D) E.e. picta

Question 30

Which statement best describes the potential effect of genetic drift in the peripheral isolate model of allopatric speciation?

A) Because the ancestral population is much smaller than the descendant populations, genetic drift can act strongly in the ancestral population.
B) Because the ancestral population is much larger than the descendant populations, genetic drift can act strongly in the ancestral population.
C) Because the descendant populations are relatively large in size, it is unlikely to see the effects of genetic drift.
D) Because the descendant populations can be founded by a relatively small number of individuals, genetic drift is more likely to have strong effects in the descendant populations.

Question 31

How can reproductive isolation in plants be mediated through pollinators?

Question 32

A population of plants experiences divergence as a result of a newly established environmental gradient. Although there is not a geographic barrier, reproduction between the two populations is increasingly rare and a hybrid zone has clearly established. As speciation continues, the hybrids experience lower and lower fecundity, and, increasingly, seeds that are produced by the hybrids are sterile. This is an example of what process?

A) reproductive character displacement
B) Dobzhansky-Muller incompatibility
C) secondary reinforcement
D) allopatric speciation

Question 33

Why is the phylogenetic species concept criticized for delineating too many species?

A) The traits used are based on morphology, leading to fine distinctions between individuals and thus more species.
B) The traits used are solely based on DNA sequences, leading to fine distinctions between individuals, which leads to fine-grained species categories.
C) The traits used must be related to gene flow; this leads to fine-grained species categories.
D) The traits used do not have to be ecologically or physiologically significant, leading to fine-grained species categories.

Question 34

The Midas and Arrow cichlid fish of Lake Apoyo appear to have speciated after a single colonization event, despite the lack of a geographical barrier in the lake to prevent the fish from continuing to interbreed as a single species. How did habitat and ecological specialization lead to speciation?

Question 35

A chromosomal rearrangement that involves the splitting of chromosomes is chromosomal

A) fusion.
B) inversion.
C) fission.
D) translocation.

Question 36

In which model of allopatric speciation is genetic drift a larger factor, and why?

Question 37

Scientists studying speciation often look at both nuclear DNA and mitochondrial DNA. Why is the genetic information obtained from mitochondrial DNA different from information obtained through nuclear DNA in sexually reproducing species?

A) In most organisms, mitochondrial DNA is inherited from the male, while nuclear DNA is inherited from both parents.
B) Mitochondrial DNA has a very low rate of mutation and is highly conserved, while nuclear DNA changes rapidly.
C) In most organisms, mitochondrial DNA is inherited from the female, while nuclear DNA is inherited from both parents.
D) Mitochondrial DNA only has one set of chromosomes, while nuclear DNA typically has multiple sets of chromosomes.

Question 38

Which choice is considered to be a fundamental problem with application of the phenetic species concept?

A) The phenetic species concept uses phenotypic traits to create clusters; therefore, it cannot be applied to bacterial and unicellular species.
B) The phenetic species concept only looks at whether reproduction occurs between populations; therefore, it cannot be applied to asexually reproducing species.
C) The phenetic species concept weighs all traits equally, which can lead to ambiguous cluster boundaries when defining species.
D) The phenetic species concept uses phenotypic traits to create clusters, but phenotypic traits can be similar due to convergent evolution rather than common ancestry.

Question 39

Changes in ploidy in plants are typically tolerated and have minor effects on survival or fertility, and it can often lead to rapid speciation. How are these changes preserved in the next generation?

A) The ability to self-fertilize enables the plant to reproduce with itself, preserving the new ploidy levels.
B) The changes can only be preserved in the next generation in plants that are capable of asexual reproduction.
C) The changes are preserved via cross-pollination with other members of the population.
D) The changes are only preserved if the exact same change occurs in multiple plants in more than one population.

Question 40

How did the morphology of the Lake Apoyo cichlids help scientists understand the sympatric speciation process in this lake?

A) Body type morphology was indicative of fish that typically live at the bottom of the lake (limnetic) and near the upper surface (benthic), separating the two species.
B) Body type morphology was indicative of fish that typically live at the bottom of the lake (benthic form) and near the upper surface (limnetic), separating the two species.
C) Body coloration was indicative of fish that live at the bottom of the lake (limnetic) and near the upper surface (benthic), separating the two species.
D) Body coloration was indicative of fish that live at the bottom of the lake (benthic) and near the upper surface (limnetic), separating the two species.

Question 41

How is the phenetic species concept similar to the phylogenetic species concept, and how do they differ?

Question 42

You are an ornithologist in the twenty-second century studying a tropical bird species that has expanded its range from its original location in Central America to where it currently exists on either side of the Rocky Mountains in North America. This range expansion is a result of a warming climate dating back to the late twentieth century. As you conduct population censuses, you realize there are phenotypic differences between populations located on the eastern and western sides of the range. You hypothesize the species has become a "ring species" as a result of the geographic isolation established by the mountains. If it was truly a ring species, what would you expect to see when you analyze the DNA of the populations and compare them to one another?

Question 43

Explain the difference(s) between prezygotic and postzygotic isolating mechanisms, and provide an example of each.

Question 44

What lines of evidence led researchers to hypothesize that black spruce and red spruce form a progenitor-derivative pair?

Question 45

Briefly describe reproductive isolation via changes in chromosome number, chromosomal rearrangement, and Dobzhansky-Muller incompatibility.

Question 46

Using the information provided in the table, apply Haldane's rule and indicate which sex is the heterogametic sex for each species.
Species
% of sex that is absent, rare, or sterile
Female Male
Woodpecker
72
5
Elephant
2
67
Fruit fly
12
82
Monarch butterfly
89
15
Squirrel
21
91

Question 47

Describe the primary difference between allopatric, parapatric, and sympatric speciation.

Question 48

The beginning of this chapter presents research conducted on mosquito populations. The researchers compared Culex pipiens and Culex pipiens molestus to confirm if they were separate species. How did they confirm they were separate species by applying the biological species concepts?