Origin of Species

Question 1

the origin of new species is at the focal point of Darwin’s evolutionary theory.

Answer 1

speciation

Question 2

must explain how new species originate and how populations evolve.

Answer 2

evolutionary theory

Question 3

consists of adaptations that evolve within a population, confined to one gene pool.

Answer 3

Microevolution

Question 4

refers to evolutionary change above the species level.

Answer 4

macroevolution

Question 5

The Biological Species Concept emphasizes __

Answer 5

reproductive isolation

Question 6

Biologists compare __, __, __, and __ when grouping organisms.

Answer 6

morphology, physiology, biochemistry, and DNA sequences

Question 7

species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations.

Answer 7

biological species concept

Question 8

Reproductive Isolation =

Answer 8

Barriers to Interbreeding

Question 9

is the existence of biological factors (barriers) that impede two different species from producing viable, fertile offspring.

Answer 9

Reproductive isolation

Question 10

are the offspring of crosses between different species.

Answer 10

Hybrids

Question 11

Reproductive isolation can be classified by whether factors act ___ or ___ fertilization.

Answer 11

before (prezygotic); after (postzygotic)

Question 12

Prezygotic barriers block fertilization from occurring
by:

Answer 12

– Impeding different species from attempting to mate.
– Preventing the successful completion of mating.
– Hindering fertilization if mating is successful.

Question 13

Prezygotic barriers maintain reproductive isolation and
include:

Answer 13

Temporal, Habitat, Behavioral, Mechanical, and
Gamete Isolation

Question 14

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.

Answer 14

Habitat isolation (e.g. Water-dwelling Thamnophis and Terrestrial Thamnophis)

Question 14

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.

Answer 14

Habitat isolation (e.g. Water-dwelling Thamnophis and Terrestrial Thamnophis)

Question 15

What are the PreZygotic Reproductive Barriers

Answer 15

• Temporal Isolation
• Behavioral isolation
• Mechanical isolation
• Gametic isolation

Question 16

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes.

Answer 16

Temporal isolation

Question 17

Courtship rituals and other behaviors unique to a species are effective barriers.

Answer 17

Behavioral isolation (e.g. Courtship ritual of blue-footed boobies)

Question 18

Morphological differences can prevent successful mating.

Answer 18

Mechanical Isolation (e.g. Bradybaena with shells spiraling in opposite directions)

Question 19

The sperm of one species may not be able to fertilize the eggs of another species.

Answer 19

Gametic isolation

Question 20

prevent the hybrid zygote from developing into a viable, fertile adult

Answer 20

Postzygotic barriers

Question 21

Species is a Latin word meaning

Answer 21

“kind” or “appearance”

Question 22

Between populations, it holds the phenotype of a population together

Answer 22

Gene flow

Question 23

Genes of the different parent species may interact and impair the hybrid’s development

Answer 23

Reduced hybrid viability

Question 24

Even if hybrids are vigorous, they may be sterile

Answer 24

Reduced hybrid fertility (e.g. Mule: sterile hybrid offspring between horse and donkey)

Question 25

Some of the first-generation hybrids are fertile, but when they mate with another species or with either parent species, the offspring of the next generation are feeble or sterile

Answer 25

hybrid breakdown

Question 26

the change in frequency of an existing gene variant in the population due to random chance.

Answer 26

genetic drift

Question 26

Some of the first-generation hybrids are fertile, but when they mate with another species or with either parent species, the offspring of the next generation are feeble or sterile

Answer 26

hybrid breakdown

Question 27

The biological species concept cannot be applied to ___.

Answer 27

- fossils - asexual organisms (including all prokaryotes)

Question 28

Other species concepts emphasize the ___ within a species rather than the __ of different species.

Answer 28

unity; separateness

Question 29

defines a species by structural features.

Answer 29

morphological species concept

Question 30

It applies to sexual and asexual species but relies on subjective criteria.

Answer 30

morphological species concept

Question 31

emphasizes the absence of gene flow

Answer 31

biological species concept

Question 32

views a species in terms of its ecological niche.

Answer 32

ecological species concept

Question 33

In ecological species concept, it applies to sexual and asexual species and emphasizes the role of ____.

Answer 33

disruptive selection

Question 34

when more extreme phenotypes (or genotypes) within a population have a fitness advantage over intermediate individuals.

Answer 34

disruptive selection

Question 35

defines a species as the smallest group of individuals on a phylogenetic tree.

Answer 35

phylogenetic species concept

Question 36

Phylogenetic species concept applies to sexual and asexual species, but it can be difficult to determine the ____ required for separate species.

Answer 36

degree of difference

Question 37

Speciation can occur in two ways

Answer 37

- Allopatric speciation: geographic barrier separates populations. – Sympatric speciation: no geographic barrier

Question 38

A population forms a new species while geographically isolated from its parent population

Answer 38

allopatric speciation

Question 39

a subset of the population forms a new species without geographic separation

Answer 39

Sympatric speciation

Question 40

In allopatric speciation, ___ is interrupted, or ___ is the cumulative effect of many speciation and extinction events.

Answer 40

gene flow; macroevolution

Question 41

separates the original population.

Answer 41

geographic barrier

Question 42

Separate populations may evolve independently through

Answer 42

- mutation - natural selection - genetic drift.

Question 43

generally increases as the distance between populations increases.

Answer 43

Reproductive isolation

Question 44

Allopatric speciation is also called

Answer 44

"Other Country" Speciation

Question 45

Barriers to reproduction are ___; separation itself is not a biological barrier.

Answer 45

intrinsic

Question 46

may arise as a result of genetic divergence

Answer 46

reproductive isolation

Question 47

speciation takes place in geographically overlapping populations.

Answer 47

sympatric speciation

Question 48

the presence of extra sets of chromosomes due to accidents during cell division.

Answer 48

polyploidy (common in plants)

Question 49

is an individual with more than two chromosome sets, derived from one species.

Answer 49

autopolyploid

Question 50

a species with multiple sets of chromosomes derived from different species.

Answer 50

allopolyploid

Question 51

a species with multiple sets of chromosomes derived from different species.

Answer 51

allopolyploid

Question 52

sources of sympatric speciation

Answer 52

- polyploidy - habitat differentiation* - natural selection - sexual selection

Question 53

can also result from the appearance of new ecological niches.

Answer 53

sympatric speciation

Question 54

can drive sympatric speciation.

Answer 54

sexual selection

Question 55

In allopatric speciation, geographic separation restricts __ between populations.

Answer 55

gene flow

Question 56

In sympatric speciation, a ____ isolates a subset of a population without geographic separation from the parent species.

Answer 56

reproductive barrier

Question 57

A hybrid zone can occur in a single band where ____.

Answer 57

adjacent species meet

Question 58

Hybrids often have ___ compared with parent species.

Answer 58

reduced fitness

Question 59

the result of mating between species with incomplete reproductive barriers

Answer 59

hybrids

Question 60

When closely related species meet in a hybrid zone, there are three possible outcomes:

Answer 60

- Reinforcement - Fusion - Stability

Question 60

Strengthening of reproductive barriers reducing gene flow.

Answer 60

reinforcement

Question 61

Weakening of reproductive barriers with eventual fusion into one species.

Answer 61

fusion

Question 62

Continued formation of hybrid individuals.

Answer 62

Stabilizing

Question 62

- occurs when hybrids are less fit than the parent species - over time, the rate of hybridization decreases - reproductive barriers should be stronger for sympatric than allopatric species

Answer 62

reinforcement of gene flow barrier

Question 63

- if hybrids are as fit as parents, there can be substantial gene flow between species - if the gene flow is great enough, the parent species can fuse into a single species

Answer 63

Fusion: Weakening Reproductive Barriers

Question 64

extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone

Answer 64

Stability: Continued Formation of Hybrid Individuals

Question 65

Broad patterns in speciation can be studied using the

Answer 65

- fossil record - morphological data - molecular data

Question 66

describe periods of apparent stasis (no change) punctuated by brief periods of rapid change.

Answer 66

punctuated equilibrium

Question 67

coined the term punctuated equilibrium

Answer 67

Niles Eldredge and Stephen Jay Gould

Question 68

The punctuated equilibrium model contrasts with a

Answer 68

Darwinian model of gradualism

Question 69

slow continuous change over time in a species’ existence.

Answer 69

Darwinian model of gradualism:

Question 70

enabling researchers to identify specific genes involved in some cases of speciation.

Answer 70

explosion of genomics

Question 71

Depending on the species in question, speciation might require the change of only __

Answer 71

a single allele or many alleles.

Question 72

the cumulative effect of many speciation and extinction events.

Answer 72

macroevolution

Question 73

the cumulative effect of many speciation and extinction events.

Answer 73

macroevolution