Chapter Objectives: Chapters 23 and 24 Species and Populations
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Explain what is meant by the modern synthesis
Explain how microevolutionary change can affect a gene pool
state the Hardy-Weinberg theorem
Write the general Hardy-Weinberg equation and use it to calculate allele and
genotype frequencies
Explain the consequences of Hardy-Weinberg equilibrium
Demonstrate that a disequilibrium population requires only one generation of
random mating to establish Hardy-Weinberg equilibrium
Describe the usefulness of the Hardy-Weinberg equilibrium model to
population genetics
List the conditions a population must meet in order to maintain HardyWeinberg equilibrium
Explain how genetic drift, gene flow, mutation, nonrandom mating, and
natural selection can cause microevolution
Explain the role of population size in genetic drift
Distinguish between the bottleneck effect and the founder effect
Explain why mutation has little quantitative effect on a large population
Describe how inbreeding and assortive mating affect a population's allele
frequencies and genotype frequencies
List factors that produce geographic variation among closely related
populations
Explain why even though mutation can be a source of genetic variability, it
contributes a negligible amount to genetic variation in a population
Explain how genetic variation may be preserved in a natural population
Describe the neutral theory of molecular evolution and explain how changes
in gene frequency may be nonadaptive
Explain what is meant by selfish DNA
Explain the concept of relative fitness and its role in adaptive evolution
Explain why the rate of decline for a deleterious allele depends upon
whether the allele is dominant or recessive to the more successful allele
Describe what selection acts on and what factors contribute to the overall
fitness of a genotype
Give examples of how an organism's phenotype may be influenced by the
environment
Distinguish among stabilizing selection, directional selection, and diversifying
selection
Define sexual dimorphism and explain how it can influence evolutionary
change
Give at leas 4 reasons why natural selection cannot breed perfect organisms
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26. Distinguish between anagenesis and cladogenesis
27. Define morphospecies and explain how this concept can be useful to
biologists
28. Define biological species (E. Mayr)
29. Describe some limitations of the biological species concept
30. Explain how gene flow between closely related species can be prevented
31. Distinguish between prezygotic and postzygotic isolating mechanisms
32. Describe 5 prezygotic isolating mechanisms and give an example of each
33. Explain why many hybrids are sterile
34. Explain how hybrid breakdown maintains separate species even if gene flow
occurs
35. Distinguish between allopatric and sympatric speciation
36. Explain the allopatric speciation model and describe the role of intraspecific
variation and geographical isolation
37. Explain why peripheral isolates are susceptible if geographic barriers arise
38. Describe the adaptive radiation model and use it to describe how it might be
possible to have many sympatric closely related species even if geographic
isolation is necessary for them to evolve
39. Define sympatric speciation and explain how polyploidy can cause
reproductive isolation
40. Distinguish between autopolyploidy and allopolyploidy
41. List some points of agreement and disagreement between the 2 schools of
thought about the tempo of speciation (gradualism vs. punctuated
equilibrium)
42. Describes the origins of evolutionary novelty
Chapter Terms:
Chapter 23 Terms
population genetics
founder effect
hybrid vigor
modern synthesis
gene flow
frequency-dependent
selection
population
mutation
species
inbreeding
neutral variation
Darwinian fitness
gene pool
assortative mating
relative fitness
genetic structure
natural selection
stabilizing selection
Hardy-Weinberg
theorem
polymorphism
directional selection
geographical variation
Hardy-Weinberg
equilibrium
diversifying selection
cline
sexual dimorphism
Hardy-Weinberg
equation
microevolution
balanced polymorphism
sexual selection
heterozygote advantage
bottleneck effect
Chapter 24 Terms
macroevoluton
morphological species concept
autopolyploid
speciation
recognition species concept
allopolyploid
anagenesis
cohesion species concept
hybrid zone
phyletic evolution
ecological species concept
punctuated equilibrium
cladogenesis
evolutionary species concept
exaptation
branching evolution
allopatric speciation
paedomorphosis
species
sympatric speciation
allometric growth
prezygotic barriers
adaptive radiation
heterochrony
postzygotic barriers
polyploidy
homeosis
Chapter Outline Framework
A. Population Genetics
1. The modern evolutionary synthesis integrated Darwinian selection
and Mendelian inheritance
2. The genetic structure of a population is defined by its allele and
genotype frequencies
3. The Hardy-Weinberg theorem describes a nonevolving population
B. Causes of Microevolution
1. Microevolution is a generation-to-generation change in a population's
allele or genotype frequencies
2. The 5 causes of microevolution are genetic drift, gene flow,
mutation, nonrandom mating, and natural selection
C. Genetic Variation, the Substrate for Natural Selection
1. Genetic variation occurs within and between populations
2. Mutation and sexual recombination generate genetic variation
3. Diploidy and balanced polymorphism preserve variation
D. Natural selection as the Mechanism of Adaptive Evolution
1. Evolutionary fitness is the relative contribution an individual makes
to the gene pool of the next generation
2. The effect of selection on a varying characteristic can be stabilizing,
directional, or diversifying
3. Sexual selection may lead to pronounced 2y differences between the
sexes
4. Natural selection cannot fashion perfect organisms
E. What is a Species?
1. The biological species concept emphasizes reproductive isolation
2. Prezygotic and postzygotic barriers isolate the gene pools of
biological species
3. The biological species concept does not work in all situations
F. Modes of Speciation
1. Geographical isolation can lead to the origin of species: allopatric
speciation
2. A new species can originate in the geographical midst of the parent
species: sympatric speciation
3. Genetic change in populations can account for speciation
4. The punctuated equilibrium model has stimulated research on the
tempo of speciation
G. The Origin of Evolutionary Novelty
1. Most evolutionary novelties are modified versions of older
structures
2. Genes that control development play a major role in evolutionary
novelty
3. An evolutionary trend does not mean that evolution is goal-oriented