Chapter 24

Question 1

How do new species originate from existing species?

Answer 1

Speciation forms a conceptual bridge between the processes of microevolution and macroevolution

Question 2

Reproductive Isolation

Answer 2

Reproductive isolation results when biological barriers impede members of two species from interbreeding and producing viable, fertile offspring

Question 3

Habitat Isolation

Answer 3

Two species that occupy different habitats within the same area may encounter each other rarely, if at all

Question 4

Temporal Isolation

Answer 4

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

Question 5

Behavioral Isolation

Answer 5

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

Question 6

Mechanical Isolation

Answer 6

Mating is attempted, but morphological differences prevent its successful completion

Question 7

Gametic Isolation

Answer 7

Sperm of one species may not be able to fertilize eggs of another species

Question 8

Reduced Hybrid Viability

Answer 8

Genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment

Question 9

Reduced Hybrid Fertility

Answer 9

Meiosis may fail to produce normal gametes, resulting in sterility, if the parent species have chromosomes of different number or structure

Question 10

Hybrid Breakdown

Answer 10

First-generation hybrids are viable and fertile, but offspring in the next generation are feeble or sterile

Question 11

morphological species concept

Answer 11

distinguishes a species by its structural features

Question 12

ecological species concept

Answer 12

defines a species by its ecological niche, the sum of its interactions with the nonliving and living parts of the environment

Question 13

allopatric speciation

Answer 13

gene flow is interrupted when a population is divided into geographically isolated subpopulations

Question 14

sympatric speciation

Answer 14

speciation occurs in populations that live in the same geographic area

Question 15

polyploidy

Answer 15

the presence of extra sets of chromosomes

Question 16

two types of polyploids

Answer 16

autopolyploids and allopollyploids

Question 17

Autopolyploids

Answer 17

have more than two sets of chromosomes, all derived from a single species

Question 18

Allopolyploids

Answer 18

have more than two sets of chromosomes, derived from different species

Question 19

hybrid zone

Answer 19

a region in which members of different species mate and produce hybrid offspring

Question 20

If hybrids do not become reproductively isolated from their parent species, then three alternate outcomes are possible:

Answer 20

-Reinforcement
-Fusion
-Stability

Question 21

Punctuated equilibria

Answer 21

describes these periods of apparent stasis punctuated by sudden change