Chapter 24

Question 1

Speciation

Answer 1

The origin of new species; at the focal point of evolutionary theory

Question 2

Microevolution

Answer 2

Changes in allele frequency in a population over time

Question 3

Macroevolution

Answer 3

Broad patterns of evolutionary change above the species level

Question 4

The Biological species concept

Answer 4

States that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

Question 5

Reproductive Isolation

Answer 5

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

Question 6

Hybrids

Answer 6

the offspring of crosses between different species

Question 7

Prezygotic barriers

Answer 7

block fertilization from occurring (Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation)

Question 8

Habitat isolation

Answer 8

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

Question 9

Temporal isolation

Answer 9

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

Question 10

Behavioral isolation

Answer 10

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

Question 11

Mechanical isolation

Answer 11

Morphological differences can prevent the successful completion of mating

Question 12

Gametic isolation

Answer 12

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

Question 13

Postzygotic barriers

Answer 13

Prevent the hybrid zygote from developing into a viable, fertile adult (Reduced hybrid viability, Reduced hybrid fertility, hybrid breakdown)

Question 14

Reduced hybrid viability

Answer 14

genes of the different parent species may interact and impair the hybrid’s development or survival in its environment

Question 15

Reduced hybrid fertility

Answer 15

Even if hybrids are vigorous, they may be sterile

Question 16

Hybrid Breakdown

Answer 16

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

Question 17

T/F: The biological species concept cannot be applied to fossils or asexual organisms

Answer 17

True

Question 18

Morphological species concept

Answer 18

Defines species by structural features (applies to sexual and asexual species but relies on subjective criteria)

Question 19

ecological species concept

Answer 19

views a species in terms of its ecological niche

Question 20

Phylogenetic species concept

Answer 20

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

Question 21

Speciation can occur in two ways: _________ speciations and ________ speciation

Answer 21

Allopatric; Sympatric

Question 22

Allopatric speciation

Answer 22

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

Question 23

T/F: Regions with less geographic barriers typically have more species than do regions with more barriers

Answer 23

False

Question 24

Sympatric Speciation

Answer 24

speciation takes place in geographically overlapping populations, but gene flow is inhibited by polyploidy, sexual selection, and habitat differentiation

Question 25

Polyploidy

Answer 25

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

Question 26

Autopolyploid

Answer 26

an individual with more than two chromosome sets, derived from a single species

Question 27

Allopolyploid

Answer 27

a species with multiple sets of chromosomes derived from different species

Question 28

Sexual Selection

Answer 28

Drives sympatric speciation

Question 29

Habitat differentiation

Answer 29

Drives sympatric speciation through new ecological niches; populations become divided into new habitats, leading to speciation

Question 30

Hybrid zone

Answer 30

A region in which members of different species mate and produce hybrids

Question 31

Three possible outcomes from hybridization events over time

Answer 31

1) Reinforcement 2) Fusion 3) Stability

Question 32

Reinforcement

Answer 32

Hybridization barriers become stronger

Question 33

Fusion

Answer 33

The species comes back together

Question 34

Stability