CHAPTER 24: THE ORIGIN OF SPECIES
I.
INTRODUCTION
A. Macroevolution–
B. Speciation–
C. Two Patterns of Speciation
1. Anagenesis–
phyletic evolution–
2. Cladogenesis–
branching evolution–
WHAT IS A SPECIES?
II.
THE BIOLOGICAL SPECIES CONCEPT EMPHASIZES REPRODUCTIVE ISOLATION
A. Species–
B. Biological species concept–
III. PREZYGOTIC AND POSTZYGOTIC BARRIERS ISOLATE THE GENE POOLS OF BIOLOGICAL SPECIES
A. Prezygotic Barriers–
1. Habitat isolation–
2. Behavioral isolation–
3. Temporal isolation–
4. Mechanical isolation–
5. Gametic isolation–
B. Postzygotic Barriers–
1. Reduced hybrid viability–
2. Reduced hybrid fertility–
3. Hybrid breakdown–
IV. THE BIOLOGICAL SPECIES CONCEPT HAS SOME MAJOR LIMITATIONS
V.
BIOLOGISTS HAVE PROPOSED SEVERAL ALTERNATIVE CONCEPTS OF SPECIES
A. Ecological Species Concept–
B. Pluralistic Species Concept–
C. Morphological Species Concept–
D. Genealogical Species Concept–
MODES OF SPECIATION
Allopatric speciation–
Sympatric speciation–
VI. ALLOPATRIC SPECIATION: GEOGRAPHICAL BARRIERS CAN LEAD TO THE ORIGIN OF SPECIES:
A. Conditions for Allopatric Speciation
B. Ring Species: Allopatric speciation in Progress?
C. Adaptive Radiation on Island Chains
D. How Do Reproductive Barriers Evolve?
1. Example of evolution of a prezygotic barrier–
2. Example of evolution of a postzygotic barrier–
E. Summary of Allopatric Speciation
VII. SYMPATRIC SPECIATION: A NEW SPECIES CAN ORIGINATE IN THE GEOGRAPHIC MIDST OF THE PARENT
SPECIES
A. Polyploidy Speciation in Plants
1. Polyploidy–
2. Autopolyploid–
3. Allopolyploid–
B. Sympatric speciation in animals
C. Summary of Sympatric Speciation
VIII. THE PUNCTUATED EQUILIBRIUM MODEL HAS STIMULATED RESEARCH ON THE TEMPO OF SPECIATION
FROM SPECIATION TO MACROEVOLUTION
IX. MOST EVOLUTIONARY NOVELTIES ARE MODIFIED VERSIONS OF OLDER STRUCTURES
A. Evolution of the Eye–
exaptations–
B. Lightweight Bones–
X.
“EVO-DEVO”: GENES THAT CONTROL DEVELOPMENT PLAY A MAJOR ROLE IN EVOLUTION
A. Allometric growth–
B. Heterochrony–
C. Paedomorphosis–
D. Homeotic genes–
XI. AN EVOLUTIONARY TREND DOES NOT MEAN THAT EVOLUTION IS GOAL ORIENTED
A. Speciation Selection