Chapter 22

Question 0

biological species concept

Answer 0

The definition of species based on the ability of populations to interbreed and produce fertile offspring

Question 1

morphological species concept

Answer 1

The concept that all individuals of a species share measurable traits that distinguish them form individuals of other species

Question 2

phylogenetic species concept

Answer 2

A concept that seeks to delineate species as the smallest aggregate population that can be united by shared derived characters

Question 3

subspecies

Answer 3

a taxonomic subdivision of a species

Question 4

ring species

Answer 4

a species with a geographical distribution that forms a ring around uninhabitable terrain

Question 5

cline

Answer 5

a pattern of smooth variation in a characteristic along a geographical gradient

Question 6

How do the morphological, biological, and phylogenetic concepts differ?

Answer 6

The morphological species concept defines species based on morphological differences among them. The biological species concept defines species as populations that can successfully interbreed under natural conditions. The phylogenetic species concept defines a species as a cluster of populations with a recent shared evolutionary history.

Question 7

What is clinal variation?

Answer 7

Clinal variation is a pattern of smooth variation along a geographical gradient

Question 8

reproductive isolating mechanism

Answer 8

a biological characteristic that prevents the gene pools of 2 species from mixing

Question 9

prezygotic isolating mechanisms

Answer 9

A reproductive isolating mechanism that act before the production of zygote, or fertilized egg

Question 10

postzygotic isolating mechanisms

Answer 10

a reproductive isolating mechanism that acts after zygotic formation

Question 11

ecological isolation

Answer 11

a prezygotic reproductive isolating mechanism in which species that live in the same geographical region occupy different habitats

Question 12

temporal isolation

Answer 12

a prezygotic reproductive isolating mechanism in which species live in the same habitat but breed at different times of day or different times of year

Question 13

behavioral isolation

Answer 13

a prezygotic reproductive isolating mechanism in which 2 species do not mate because of differences in courtship behavior; also known as ethological isolation

Question 14

mechanical isolation

Answer 14

a prezygotic reproductive isolating mechanism caused by differences in the structure of reproductive organs or other body parts

Question 15

gametic isolation

Answer 15

a prezygotic reproductive isolating mechanism caused by incompatibility between the sperm of 1 species and the egg of another; may prevent fertilization

Question 16

hybrid inviability

Answer 16

a postzygotic reproductive isolating mechanism in which a hybrid individual has a low probability of survival to reproductive age

Question 17

hybrid sterility

Answer 17

a postzygotic reproductive isolating mechanism in which hybrid offspring cannot form functional gametes

Question 18

hybrid breakdown

Answer 18

a postzygotic reproductive isolating mechanism in which hybrids are capable of reproducing, but their offspring have either reduced fertility or reduced viability

Question 19

What is the difference between prezygotic and postzygotic isolating mechanisms?

Answer 19

prezygotic isolating mechanisms either prevent individuals of different species from mating or prevent sperm of one species from fertilizing the egg of another. postzygotic isolating mechanisms limit the survivorship or reporductive capability of hybrid individuals.

Question 20

When a male duck of one species preformed a courtship display to a female of another species, she interpreted his behavior as aggressive rather than amorous. What type of reproductive mechanism does this scenario illustrate?

Answer 20

The scenario illustrates a behavioral isolating mechanism

Question 21

allopatric speciation

Answer 21

the evolution of reproductive isolating mechanisms between 2 populations that are geographically separated

Question 22

species cluster

Answer 22

a group of closely related species recently descended from a common ancestor

Question 23

hybrid zones

Answer 23

a geographical area where the hybrid offspring of 2 divergent populations or species are common

Question 24

reinforcement

Answer 24

the enhancement of reproductive isolation that had begun to develop while populations were geographically separated

Question 25

parapatric speciation

Answer 25

speciation between populations with adjacent geographical distributions

Question 26

sympatric speciation

Answer 26

speciation that occurs without the geographical isolation of populations

Question 27

host race

Answer 27

a population of insects that may be reproductively isolated from other populations of the same species as a consequence of their adaptation to feed on a specific host plant species

Question 28

polypoidy

Answer 28

the condition of having one or more extra copies of the entire haploid complement of chromosomes

Question 29

What are the 2 stages required for allopatric speciation?

Answer 29

In the first stage of allopatric speciation, populations become geographically separated. in the second stage, they become reproductively isolated

Question 30

What factor appears to promote parapatric speciation in bent grass?

Answer 30

Some populations of bent grass survive better on unpolluted soil, whereas others survive better on polluted soil

Question 31

Why might insects form different host races be unlikely to mate with each other?

Answer 31

Insects from different host races spend most of their time on different host plant species. Thus, they rarely encounter each other and would be unlikely to mate under natural conditions

Question 32

autopolypoidy

Answer 32

the genetic condition of having more than 2 sets of chromosomes from the same parent species

Question 33

unreduced gametes

Answer 33

a gamete that contains the same number of chromosomes as a somatic cell

Question 34

allopolyploidy

Answer 34

the genetic condition of having 2 or more complete sets of chromosomes from different parent species

Question 35

how can natural selection promote reproductive isolation in allopatric populations?

Answer 35

natural selection cannot promote reproduction isolation in allopatric populations directly, but it can lead to genetic divergence which results in reproductive isolation

Question 36

how does polyploidy promote speciation in plants

Answer 36

polyploidy changes the number of chromosomes sets in cells of an organism. polyploidy individuals are often reproductively isolated from their parent species because their gametes contain different number of chromosomes. when a gamete from a polyploidy individual fuses with a gamete from a nonpolyploidy individual, the resulting offspring is usually sterile because the odd number of chromosomes cannot segregate properly during meiosis