Ch 21: Species and Speciation

Question 1

Speciation

Answer 1

The process whereby new species are produced.

Question 2

Species

Answer 2

A group of individuals that can exchange genetic material through interbreeding to produce fertile offspring.

Question 3

Biological Species Concept

Answer 3

As described by Ernst Mayr, the concept that “species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.” The BSC is the most widely used and accepted definition of a species, but cannot be applied to asexual organisms.

Question 4

Morphospecies Concept

Answer 4

The idea that members of the same species usually look like each other more than like other species.

Question 5

Hybrid Offspring

Answer 5

The offspring produced by a cross; sometimes applied specifically to interbreeding between two closely related species.

Question 6

Hybridization

Answer 6

Interbreeding between two different varieties or species.

Question 7

Niche

Answer 7

The combination of traits and habitat in which a species exists.

Question 8

Ecological Species Concept

Answer 8

The concept that there is a one-to-one correspondence between a species and its niche.

Question 9

Phylogenetic Species Concept

Answer 9

The idea that members of a species all share a common ancestry and a common fate.

Question 10

Pre-zygotic

Answer 10

Describes factors that prevent the fertilization of an egg.

Question 11

Post-zygotic

Answer 11

Describes factors that cause the failure of the fertilized egg to develop into a fertile individual.

Question 12

Behaviorally Isolated

Answer 12

Describes individuals that only mate with other individuals on the basis of specific courtship rituals, songs, and other behaviors.

Question 13

Gametic Isolation

Answer 13

Incompatibility between the gametes of different individuals (typically belonging to different species).

Question 14

Mechanical Incompatibility

Answer 14

Structural configuration of the genitalia that prevents mating with another individual (typically of another species).

Question 15

Temporal Isolation

Answer 15

Pre-zygotic isolation between individuals that are reproductively active at different times.

Question 16

Geographic Isolation

Answer 16

Spatial segregation of individuals.

Question 17

Ecological Isolation

Answer 17

Pre-zygotic isolation between individuals that specialize ecologically in different ways.

Question 18

Genetic Incompatability

Answer 18

Genetic dissimilarity between two organisms, such as different numbers of chromosomes, that is sufficient to act as a post-zygotic isolating factor.

Question 19

Partially Reproductive Isolation

Answer 19

Describes populations that have not yet diverged into separate species but whose genetic differences are extensive enough for the hybrid offspring they produce to have reduced fertility or viability compared with offspring produced by crosses between individuals within each population.

Question 20

Allopatric Speciation

Answer 20

Describes populations that are geographically separated from each other.

Question 21

Subspecies

Answer 21

Allopatric populations that have yet to evolve even partial reproductive isolation but which have acquired population-specific traits.

Question 22

Dispersal

Answer 22

The process in which some individuals colonize a distant place far from the main source population.

Question 23

Vicariance

Answer 23

The process in which a geographic barrier arises within a single population, separating it into two or more isolated populations that are isolated from each other.

Question 24

Peripatric Speciation

Answer 24

A specific kind of allopatric speciation in which a few individuals from a mainland population disperse to a new location remote from the original population and evolve separately.

Question 25

Mainland Population

Answer 25

The central and largest population of a species.

Question 26

Island Population

Answer 26

An isolated population; may apply to true islands (land surrounded by water) or to ecological islands that similarly isolate their inhabitants (for example ponds, for fish).

Question 27

Adaptive Radiation

Answer 27

A period of unusually rapid evolutionary diversification in which natural selection accelerates the rate of speciation within a group, with new species adapted for specific niches.

Question 28

Co-speciation

Answer 28

A process in which two groups of organisms speciate in response to each other and at the same time, producing matching phylogenies.

Question 29

Sympatric Population

Answer 29

Describes populations that are in the same geographic location.

Question 30

Instantaneous Speciation

Answer 30

Speciation that occurs in a single generation.

Question 31

T/F: Given the generation time of certain organisms, the biological species concept can be difficult to test.

Answer 31

True

Question 32

The reason that lions, which live in Africa, and tigers, which live in Asia, do not produce ligers (infertile offspring of lions and tigers) in the wild is likely the result of:

Answer 32

ecological isolation of lions and tigers.

Question 33

_____ is the process by which two populations of the same species living in the same habitat diverge into separate species.

Answer 33

Sympatric speciation

Question 34

T/F: If two populations are reproductively isolated from one another, they must be genetically isolated from each other and, therefore, cannot belong to the same species.

Answer 34

False

Question 35

In the southwestern desert of the United States there are temporary ponds that form only after heavy summer rains. As a naturalist, you visit these ponds and notice that female frogs mate with males of their own species, which are identified solely by listening to male calls. The lack of mating between species would be an example of _____ and _____.

Answer 35

pre-zygotic isolation; behavioral isolation

Question 36

In _____ speciation, there is gene flow between populations that are in the process of diverging into two or more species. In _____ speciation, there is no gene flow between populations that are in the process of diverging into two or more species.

Answer 36

sympatric; allopatric

Question 37

Imagine that a zoo in Sri Lanka has started an elephant-breeding program. Zookeepers have introduced an Indian and Sri Lankan elephant into the same enclosure. What will be the result of this mating?

Answer 37

This mating will demonstrate that these elephants are members of the same species and will produce fertile offspring.

Question 38

T/F: Natural selection is always the driving force of speciation.

Answer 38

False

Question 39

A researcher is trying to determine whether different populations of asexually reproducing bacteria belong to the same species. What concept will be most helpful in making this determination?

Answer 39

the ecological species concept

Question 40

If two individuals from different species attempt to mate, but fertilization fails to occur, this is likely the result of _____. However, if such a mating produces a zygote that fails to form a viable embryo, this is likely the result of _____.

Answer 40

pre-zygotic factors; post-zygotic factors

Question 41

T/F: Adaptive radiation is more likely to occur in a population produced by a dispersal event than in a long-established population on a continent.

Answer 41

True

Question 42

While in South America, you come across what you think are two groups of birds in the same location. They are nearly identical aside from their color. After years of observation, you conclude that the birds eat similar diets and share similar behaviors but do not reproduce with each other. These groups of birds appear to be an example of:

Answer 42

two different species on the basis of reproductive behavior.

Question 43

T/F: Post-zygotic reproductive isolation may be due to temporal or ecological separation.

Answer 43

False

Question 44

T/F: In general, allopatric species will evolve pre-zygotic isolating mechanisms more rapidly than sympatric species.

Answer 44

False

Question 45

T/F: You would expect similar species with a different number of chromosomes to be genetically compatible and, therefore, able to reproduce fertile offspring.

Answer 45

False

Question 46

Ronald Fisher developed a critical idea for the modern synthesis of Darwin and Mendel. What is the basis of this synthesis?

Answer 46

Multiple genes can explain the continuous nature of most observed traits.

Question 47

Migration tends to _____ genetic differences among populations.

Answer 47

Decrease

Question 48

Competition among members of one sex for access to the other sex results in _____ selection.

Answer 48

Sexual

Question 49

You are researching a population of moles. In the course of your research, you identify a nearby population that occasionally comes into contact with your study population. What best describes the evolutionary process at work?

Answer 49

gene flow

Question 50

If two populations are thought to be diverging from one another, what would you expect to observe?

Answer 50

an accumulation of different mutations in different populations

Question 51

Individuals that are heterozygous for the sickle-cell anemia allele are more resistant to malaria than those that do not have a sickle-cell allele. Why does the sickle-cell allele not become fixed in the population?

Answer 51

Individuals that are homozygous for the sickle-cell allele have sickle-cell anemia, and are at a fitness disadvantage.

Question 52

A gene that no longer retains function is called:

Answer 52

a pseudogene.

Question 53

Is natural selection the same thing as evolution?

Answer 53

No, because forces other than natural selection can also cause evolution.

Question 54

T/F: A population experiencing genetic drift will be in Hardy-Weinberg equilibrium.

Answer 54

False

Question 55

T/F: All mutations in a population—both harmful and beneficial—contribute to the evolution of that population.

Answer 55

True

Question 56

T/F: Migration, genetic drift, and mutation are all mechanisms of evolutionary change.

Answer 56

True

Question 57

What is the eventual long-term result of different mutations accumulating in different populations?

Answer 57

the evolution of different species

Question 58

Why is it thought that the majority of natural selection is stabilizing selection?

Answer 58

Most mutations are deleterious and produce an extreme phenotype that is selected against.

Question 59

Dodos were flightless birds that have been extinct for about 300 years. Imagine that biologists found two surviving dodos on present-day Earth and mated this pair of birds. What would you expect of the resulting dodo population?

Answer 59

Due to a population bottleneck, the frequency of alleles in this new dodo population may be very different from the frequencies expected in larger, now non-existent, populations.

Question 60

Some proteins have a slower molecular clock due to ______ selection, which eliminates harmful alleles.

Answer 60

negative

Question 61

Mutation and recombination are the only processes that can increase genetic variation because they are also the only processes that:

Answer 61

can produce new genotypes.