Origin of Species

Question 1

Macroevolution

Answer 1

• is the broad pattern of evolution above the species level
• is changes over time in allele frequencies in a population

Question 2

What is an example of macroevolution?

Answer 2

the origin of eyes capable of producing a focused image in both invertebrates and vertebrates

Question 3

What are examples of microevolution?

Answer 3

• the spread of antibiotic resistance within a population of bacteria
• decrease in the prevalence of the sickle-cell allele in populations outside the range of mosquitoes that transmit malaria
• selection against a form of albinism caused by a genetic change at a single locus

Question 4

Biological Species Concept

Answer 4

holds that populations belong to the same species if they can contribute genes to a common gene pool

Question 5

What do reproductive barriers do?

Answer 5

they block gene flow between different species

Question 6

What is the criteria for the biological species concept?

Answer 6

• ability to create viable
• fertile offspring

Question 7

What is an advantage of biological species concept?

Answer 7

• objective criteria
• meshes well with gene flow concept

Question 8

What is a disadvantage of biological species concept?

Answer 8

not applicable to extinct or asexual species

Question 9

What is the criteria for morphological species concept?

Answer 9

similarities in body structure

Question 10

What is an advantage of morphological species concept?

Answer 10

• easy to apply
• works for asexual and extinct species

Question 11

What is a disadvantage to morphological species concept?

Answer 11

researchers may disagree on which structures are important

Question 12

What is the criteria for phylogenetic species concept?

Answer 12

common evolutionary history

Question 13

What is an advantage to phylogenetic species concept?

Answer 13

• based on actual relationships
• works for asexual and extinct species

Question 14

What is a disadvantage to phylogenetic species concept?

Answer 14

requires good evolutionary histories

Question 15

Behavioral Isolation

Answer 15

differences in mating rituals or displays

Question 16

Is behavioral isolation pre-zygotic or pos-zygotic reproductive barrier?

Answer 16

pre-zygotic

Question 17

What is an example of behavioral isolation?

Answer 17

different bird species display feathers of different colors during mating display

Question 18

Temporal Isolation

Answer 18

differences in the timing of mating

Question 19

Is temporal isolation a pre-zygotic or post-zygotic reproductive barrier?

Answer 19

pre-zygotic

Question 20

What is an example of temporal isolation?

Answer 20

one plant species flowers before dawn while a related species flowers in the late afternoon

Question 21

Habitat Isolation (reproductive barrier)

Answer 21

difference in habitat occupied

Question 22

Is habitat isolation a pre-zygotic or post-zygotic reproductive barrier?

Answer 22

pre-zygotic

Question 23

What is an example of habitat isolation?

Answer 23

different ticks live on different host species

Question 24

Mechanical Isolation (reproductive barrier)

Answer 24

reproductive structure incompatibility

Question 25

Is mechanical isolation a pre-zygotic or post-zygotic reproductive barrier?

Answer 25

pre-zygotic

Question 26

What is an example of mechanical isolation?

Answer 26

differently shaped snail shells prevent alignment of genital openings

Question 27

Gametic Isolation

Answer 27

sperm and egg are incompatible

Question 28

Is gametic isolation pre-zygotic or post-zygotic reproductive barrier?

Answer 28

pre-zygotic

Question 29

What is an example of gametic isolation?

Answer 29

different coral species release gametes into the water (but only gametes of conspecifics can fuse)

Question 30

Reduced Hybrid Viability (reproductive barrier)

Answer 30

hybrid offspring are produced but are feeble or unable to compete for mates

Question 31

Is reduced hybrid viability pre-zygotic or post-zygotic reproductive barrier?

Answer 31

pos-zygotic

Question 32

What is an example of reduced hybrid viability?

Answer 32

two species of fish successfully interbreed but their offspring don't live to maturity

Question 33

Reduced Hybrid Fertility (reproductive barrier)

Answer 33

hybrid offspring are produced but are sterile

Question 34

Is reduced hybrid fertility pre-zygotic or post-zygotic reproductive barrier?

Answer 34

post-zygotic

Question 35

What is an example of reduced hybrid fertility?

Answer 35

horses can be mated with zebras (but their offspring are sterile)

Question 36

Genetic Drift

Answer 36

- is a random change in allele frequencies over time - is due to chance events that alter allele frequencies

Question 37

Why are large finches now living on the Galápagos Islands different from the original source population from a nearby island?

Answer 37

- genetic drift occurred in the two populations - natural selection favored individuals that were more fit in the new environment - the separation of habitats reduced gene flow between the populations

Question 38

Reinforcement (disruptive selection)

Answer 38

- is a type of natural selection - which favors extreme phenotypes over intermediate phenotypes

Question 39

Allopatric Speciation

Answer 39

- occurs when a species separates into two separate groups which are isolated from one another

Question 40

How long does it take new species to form on Earth?

Answer 40

the time required varies considerably

Question 41

Natural Selection Effects

Answer 41

- consistently causes a population to become better adapted to its environment - a result of differential success in reproduction - cannot cause a harmful allele to become more common

Question 42

Genetic Drift Effects

Answer 42

- can result from the founder effect - can result from the bottleneck effect - causes allele frequencies to fluctuate randomly

Question 43

Gene Flow Effects

Answer 43

- can introduce new alleles into a population's gene pool - a result of the movement of fertile individuals or their gametes

Question 44

Disruptive Selection

Answer 44

- eliminated phenotypes near the average and favors the extreme phenotypes - resulting in increased genetic variation in a population

Question 45

What is the result of heterozygote advantage?

Answer 45

more genetic variation in the population

Question 46

Directional Selection

Answer 46

- drives the average of the population in one direction - when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other

Question 47

Stabilizing Selection

Answer 47

- causes no change in the average of the population - extreme phenotypes become less common

Question 48

What is an adaptation?

Answer 48

a structure or function that is advantageous in a particular environment

Question 49

What is an example of an adaptation?

Answer 49

ground-trunk anoles have evolved long legs that enable them to dart down from a tree trunk and catch prey on the ground with minimum vulnerability to predators

Question 50

Define a species

Answer 50

is a group of individuals that can mate and produce fertile offspring together