Chapter 24: The Origin of Species

Question 1

Speciation

Answer 1

• Process by which one species splits into two or more species
• The “Mystery of Mysteries”

Question 2

Microevolution

Answer 2

Changes over time in allele frequencies in populations

Question 3

Macroevolution

Answer 3

Broad pattern of evolution above the species level

Question 4

Biological Species Concept

Answer 4

• Concept that states a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
• These groups do not produce such offspring with other groups

Question 5

Species

Answer 5

Population or group of populations whose members can interbreed and produce fertile offspring but do not produce viable, fertile offspring with members of other such groups

Question 6

Reproductive Isolation

Answer 6

• Existence of biological factors (barriers)

- Hinders members of two different species from interbreeding and producing viable, fertile offspring

Question 7

Hybrids

Answer 7

Offspring that result from interspecific mating

Question 8

Prezygotic Barriers

Answer 8

• Block fertilization from occurring
• Impede the attempt of mating
• Prevent an attempt of mating from being completed successfully
• Prevent fertilization directly

Question 9

Post Zygotic Barriers

Answer 9

Barriers to help reproductive isolation if the prezygotic barriers are bypassed and a zygote is formed

Question 10

Morphological Species Concept

Answer 10

• Emphasizes the unity within a species
• Distinguishes a species by body shape and other structural features
• Mainly used by scientists but relies on subjective judgement

Question 11

Ecological Species Concept

Answer 11

Defines a species in terms of its ecological niche

Question 12

Ecological Niche

Answer 12

Sum of how members of a species interact with the nonliving and living parts of their environment

Question 13

Phylogenetic Species Concept

Answer 13

Defines a species as the smallest group of individuals that can share a common ancestor

Question 14

Allopatric Speciation

Answer 14

When gene flow is interrupted by populations being isolated into geographic subgroups

Question 15

Sympatric Speciation

Answer 15

Speciation occurs in populations that occupy the same environmental area

Question 16

Polyploidy

Answer 16

A chromosomal alteration in which the organism possesses more than two complete chromosome sets

Question 17

Autopolyploid

Answer 17

• An individual that has > 2 chromosome sets that are all derived from a single species
• Can cause reproductive isolation without geographic separation

Question 18

Allopolyploid

Answer 18

• A fertile individual that has > 2 chromosome sets as a result of two different species interbreeding and combining their chromosomes
• Fertile with each other but not with either parent species

Question 19

Hybrid Zone

Answer 19

• Region where members of different species will meet and mate, which produces offspring with mixed ancestry
• Caused by a species with incomplete reproductive barriers coming in contact with another

Question 20

Adaptive Radiation

Answer 20

Organisms diversify quickly from a common ancestor

Question 21

Reinforcement

Answer 21

Process where natural selection strengthens prezygotic barriers because of the hybrids’ unfitness to the environment

Question 22

Punctuated Equilibrium

Answer 22

• Pattern of evolution

- Long stable periods are interrupted by periods of more rapid change

Question 23

Gradual Speciation

Answer 23

Species diverge gradually over time in small steps

Question 24

Analogous Structures

Answer 24

Body parts that share a common function but not structure

Question 25

Convergent Evolution

Answer 25

When different organisms independently evolve similar traits

Question 26

Divergent Evolution

Answer 26

Process by which interbreeding species diverged into two or more evolutionary groups

Question 27

Homologous Structures

Answer 27

Structures in different species that are similar because of common ancestry

Question 28

Coevolution

Answer 28

Process by which two species evolve in response to changes in each other