Lecture 2 Variation and Adaptation

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• B. Phenotype
• C. Fitness
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• Entire genetic make-up of an organism.
• B. Phenotype
• C. Fitness
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• Entire genetic make-up of an organism.
• B. Phenotype
• What an organism looks like and how it
  functions and behaves.
• C. Fitness
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• Entire genetic make-up of an organism.
• B. Phenotype
• What an organism looks like and how it
  functions and behaves. Includes morphology,
  anatomy, physiology, and behavior.
• C. Fitness
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• Entire genetic make-up of an organism.
• B. Phenotype
• What at organism looks like and how it
  functions and behaves. Includes morphology,
  anatomy, physiology, and behavior.
• C. Fitness
• 1. Proportional contribution of an
  individual to the next generation.
• 2.
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• A. Genotype
• Entire genetic make-up of an organism.
• B. Phenotype
• What an organism looks like and how it
  functions and behaves. Includes morphology,
  anatomy, physiology, and behavior.
• C. Fitness
• 1. Proportional contribution of an
  individual to the next generation.
• 2. Number of offspring produced by an
  individual relative to the
• number produced by all individuals in the
  population.
• D. Evolution
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• D. Evolution
• 1. Conceptual definition
• 2. Operational definition
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• D. Evolution
• 1. Conceptual definition Descent with
  modification of genotype
• and phenotype.
• 2. Operational definition
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• D. Evolution
• 1. Conceptual definition Descent with
  modification of genotype
• and phenotype.
• 2. Operational definition Expressed
  change in allele frequencies in
• a population from generation to generation.
• E. Primary mechanisms of evolution

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• E. Primary mechanisms of evolution (what can
  cause changes in allele frequencies in a
  population?)

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• E. Primary mechanisms of evolution (what can
  cause changes in allele frequencies in a
  population?)
• 1. Natural selection
• 2. Genetic drift
• 3. Gene flow

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• E. Primary mechanisms of evolution (what can
  cause changes in allele frequencies in a
  population?)
• 1. Natural selection change in allele
  frequencies in future generations
• due to heritable differences in traits that
  affect survival and
• reproduction.
• 2. Genetic drift
• 3. Gene flow

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• E. Primary mechanisms of evolution (what can
  cause changes in allele frequencies in a
  population?)
• 1. Natural selection change in allele
  frequencies in future generations
• due to heritable differences in traits that
  affect survival and
• reproduction.
• 2. Genetic drift stochastic (random)
  change in allele frequencies in
• small populations or in populations with very
  few individuals
• involved in mating.
• 3. Gene flow

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Lecture 2 Variation and Adaptation

• I. Background Definition and Concepts
• E. Primary mechanisms of evolution (what can
  cause changes in allele frequencies in a
  population?)
• 1. Natural selection change in allele
  frequencies in future generations
• due to heritable differences in traits that
  affect survival and
• reproduction.
• 2. Genetic drift stochastic (random)
  change in allele frequencies in
• small populations or in populations with very
  few individuals
• involved in mating.
• 3. Gene flow change in allele
  frequencies due to immigration and
• emigration.

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic environment
• 1. Spatial variation
• a. Large-scale
• b. Small-scale
• 2. Temporal variation
• a. Long-term
• b. Short-term

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 1. Spatial variation
• a. Large-scale
• b. Small-scale
• 2. Temporal variation
• a. Long-term
• b. Short-term

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 1. Spatial variation
• a. Large-scale tremendous variation in
  temperature, precipitation,
• and other environmental factors as you
  move from the equator to
• the poles or from one continent to
  another (FIG. 1e).
• b. Small-scale
• 2. Temporal variation
• a. Long-term
• b. Short-term

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 1. Spatial variation
• a. Large-scale tremendous variation in
  temperature, precipitation,
• and other environmental factors as you
  move from the equator to
• the poles or from one continent to
  another (FIG. 1e).
• b. Small-scale surprising variation
  within a small area (FIG. 2).
• 2. Temporal variation
• a. Long-term
• b. Short-term

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 1. Spatial variation
• a. Large-scale tremendous variation in
  temperature, precipitation,
• and other environmental factors as you
  move from the equator to
• the poles or from one continent to
  another (FIG. 1e).
• b. Small-scale surprising variation
  within a small area (FIG. 2).
• Different environmental conditions make
  it possible for
• different organisms to coexist in a
  fairly small area.
• 2. Temporal variation
• a. Long-term
• b. Short-term

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 2. Temporal variation
• a. Long-term the environment at any one
  spot on Earth has
• changed dramatically over geologic time
  (FIG. 1).
• b. Short-term (FIG. 3).

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Lecture 2 Variation and Adaptation

• II. Variation
• A. Variation in abiotic (non-living, physical)
  environment
• 2. Temporal variation
• a. Long-term the environment at any one
  spot on Earth has
• changed dramatically over geologic time
  (FIG. 1).
• b. Short-term the environment at any one
  spot changes from day
• to day and even during the course of a
  single day (FIG. 3).

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an organism?

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an organism? There
  are three main sources of variation among
  different species and even among individuals of
  the same species.

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation (FIG. 4)
• 2. Environmental variation (FIG. 5)
• 3. Ontogenetic variation

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation different
  environments select for different
• genetically distinct races of a species
  (ecotypes)(FIG. 4).
• 2. Environmental variation
• 3. Ontogenetic variation

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation different
  environments select for different
• genetically distinct races of a
  species (ecotypes)(FIG. 4).
• 2. Environmental variation (FIG. 5).
• 3. Ontogenetic variation

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation different
  environments select for different
• genetically distinct races of a
  species (ecotypes)(FIG. 4).
• 2. Environmental variation a single
  genotype may express a different
• phenotype when placed in different
  environments (phenotypic
• plasticity)(FIG. 5).
• 3. Ontogenetic variation

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation different
  environments select for different
• genetically distinct races of a
  species (ecotypes)(FIG. 4).
• 2. Environmental variation a single
  genotype may express a different
• phenotype when placed in different
  environments (phenotypic
• plasticity)(FIG. 5).
• 3. Ontogenetic variation

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Lecture 2 Variation and Adaptation

• II. Variation
• B. Variation in organisms What factors
  determine the phenotype of an
• organism? There are three main sources of
  variation among different
• species and even among individuals of the
  same species.
• 1. Genetic variation different
  environments select for different
• genetically distinct races of a
  species (ecotypes)(FIG. 4).
• 2. Environmental variation a single
  genotype may express a different
• phenotype when placed in different
  environments (phenotypic
• plasticity)(FIG. 5).
• 3. Ontogenetic variation organisms
  change as they develop from
• juveniles to adults.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary ______ by which
  organisms become better
• suited to their environment.
• 2. A genetically determined _________ that
  improves an organisms
• ability to _______ and ________ in a
  particular environment but also
• _______ the organism to life in a narrow range
  of conditions.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary process by which
  organisms become better
• suited to their environment.
• 2. A genetically determined _________ that
  improves an organisms
• ability to _______ and ________ in a
  particular environment but also
• _______ the organism to life in a narrow range
  of conditions.

42
Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary process by which
  organisms become better
• suited to their environment.
• 2. A genetically determined characteristic
  that improves an organisms
• ability to ______ and _______ in a particular
  environment but also
• _______ the organism to life in a narrow range
  of conditions.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary process by which
  organisms become better
• suited to their environment.
• 2. A genetically determined characteristic
  that improves an organisms
• ability to survive and reproduce in a
  particular environment but also
• _______ the organism to life in a narrow range
  of conditions.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary process by which
  organisms become better
• suited to their environment.
• 2. A genetically determined characteristic
  that improves an organisms
• ability to survive and reproduce in a
  particular environment but also
• restricts the organism to life in a narrow
  range of conditions.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• A. Definitions
• 1. The evolutionary process by which
  organisms become better
• suited to their environment.
• 2. A genetically determined characteristic
  that improves an organisms
• ability to survive and reproduce in a
  particular environment but also
• restricts the organism to life in a narrow
  range of conditions. John
• Harper calls this the rut of specialization
  because there is a
• trade-off for adapting to specific conditions.

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 1. Deleterious mutations
• 2. Immigration
• 3. Changing environmental conditions
• 4. Limited resources
• 5. Historical constraints of past
  phenotypes

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 1. Deleterious mutations mutations in
  genome constantly occur and
• most have no effect or reduce fitness.
• 2. Immigration
• 3. Changing environmental conditions
• 4. Limited resources
• 5. Historical constraints of past
  phenotypes

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 1. Deleterious mutations mutations in
  genome constantly occur and
• most have no effect or reduce fitness.
• 2. Immigration introduces new alleles
  that are less adaptive to the
• environment.
• 3. Changing environmental conditions
• 4. Limited resources
• 5. Historical constraints of past
  phenotypes

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 1. Deleterious mutations mutations in
  genome constantly occur and
• most have no effect or reduce fitness.
• 2. Immigration introduces new alleles
  that are less adaptive to the
• environment.
• 3. Changing environmental conditions
  adaptation is to past conditions
• experienced by ancestors. If conditions
  change, then previously
• adaptive traits may not be beneficial.
• 4. Limited resources
• 5. Historical constraints of past
  phenotypes

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 4. Limited resources results in
  trade-offs. For example, fish-eating
• birds like loons have wings that make them
  powerful divers but they
• are poor flyers.
• 5. Historical constraints of past
  phenotypes

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Lecture 2 Variation and Adaptation

• III. Adaptation
• B. Constraints on adaptation (adaptation doesnt
  produce ideal phenotypes)
• 4. Limited resources results in
  trade-offs. For example, fish-eating
• birds like loons have wings that make them
  powerful divers but they
• are poor flyers.
• 5. Historical constraints of past
  phenotypes adaptation involves
• tinkering with existing structures so only
  limited change is possible
• (Richard Dawkins).

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits
• Hypothesis 2. Maximum brooding capacity
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs.
• Hypothesis 2. Maximum brooding capacity
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed.
• Hypothesis 2. Maximum brooding capacity
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50.
• Hypothesis 2. Maximum brooding capacity
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50. Conclusion? Clutch size not due to
  physiological limits.
• Hypothesis 2. Maximum brooding capacity
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50. Conclusion? Clutch size not due to
  physiological limits.
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50. Conclusion? Clutch size not due to
  physiological limits.
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected. Use egg addition
  experiment to test. Each time female leaves
  nest, an egg is added.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50. Conclusion? Clutch size not due to
  physiological limits.
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected. Use egg addition
  experiment to test. Each time female leaves
  nest, an egg is added. What happens? Gannet
  (fish-eating seabird) broods 2 instead of 1 egg,
  and partridge broods 20 instead of 15.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 1. Physiological limits.
  Perhaps females are not physiologically able to
  lay more eggs. Use egg removal experiment to
  test. Each time female leaves nest an egg is
  removed. What happens? Herring gulls, which
  normally lay 2 to 3 eggs, lay up to 16. House
  sparrows, which normally lay 3 to 5 eggs, lay up
  to 50. Conclusion? Clutch size not due to
  physiological limits.
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected. Use egg addition
  experiment to test. Each time female leaves
  nest, an egg is added. What happens? Gannet
  (fish-eating seabird) broods 2 instead of 1 egg,
  and partridge broods 20 instead of 15.
  Conclusion? Clutch size not limited by brooding
  capacity.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7)

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected. Use egg addition
  experiment to test. Each time female leaves
  nest, an egg is added. What happens? Gannet
  (fish-eating seabird) broods 2 instead of 1 egg,
  and partridge broods 20 instead of 15.
  Conclusion? Clutch size not limited by brooding
  capacity.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7). Conclude that potential
  benefits of laying more eggs are outweighed by
  the costs.
• Benefits?
• Costs?

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 2. Maximum brooding capacity.
  Perhaps females cant cover more eggs to keep
  them warm and protected. Use egg addition
  experiment to test. Each time female leaves
  nest, an egg is added. What happens? Gannet
  (fish-eating seabird) broods 2 instead of 1 egg,
  and partridge broods 20 instead of 15.
  Conclusion? Clutch size not limited by brooding
  capacity.
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7). Conclude that potential
  benefits of laying more eggs are outweighed by
  the costs.
• Benefits? Potentially more descendents and
  greater fitness.
• Costs?

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Lecture 2 Variation and Adaptation

• III. Adaptation
• C. Example. What determines optimal clutch size
  in bird species?
• Hypothesis 3. Greatest benefit-to-cost
  ratio (FIGS. 6,7). Conclude that
• potential benefits of laying more eggs are
  outweighed by the costs.
• Benefits? Potentially more descendents and
  greater fitness.
• Costs? Using more energy to lay brood
  eggs and feed young may reduce survival or future
  reproduction of mother. More mouths to feed may
  mean fewer young survive. More trips to get food
  may expose mother and young to predators.

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• A. Definitions
• 1. Proximate factors
• 2. Ultimate factors
• B. Example 1 - Why do snowshoe hares turn white
  in winter?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• A. Definitions
• 1. Proximate factors - immediate
  environmental causes or physiological
• explanations of some trait or behavior.
• 2. Ultimate factors
• B. Example 1 - Why do snowshoe hares turn white
  in winter?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• A. Definitions
• 1. Proximate factors - immediate
  environmental causes or physiological
• explanations of some trait or behavior.
• 2. Ultimate factors - the evolutionary
  reason or adaptive value or
• advantage of a trait or behavior.
• B. Example 1 - Why do snowshoe hares turn white
  in winter?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• A. Definitions
• 1. Proximate factors - immediate
  environmental causes or physiological
• explanations of some trait or behavior.
• 2. Ultimate factors - the evolutionary
  reason or adaptive value or
• advantage of a trait or behavior.
• B. Example 1 - Why do snowshoe hares turn white
  in winter? Two questions
• 1. What happens environmentally
  physiologically to cause hares to
• lose their brown fur and grow white fur?
• 2. What is the advantage of turning white
  in winter and brown in
• summer?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• B. Example 1 - Why do snowshoe hares turn white
  in winter? Two questions
• 1. What happens environmentally
  physiologically to cause hares to
• lose their brown fur and grow white fur?
  Answer?
• 2. What is the advantage in turning white
  in winter and brown in
• summer?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• B. Example 1 - Why do snowshoe hares turn white
  in winter? Two questions
• 1. What happens environmentally
  physiologically to cause hares to
• lose their brown fur and grow white fur?
  Answer? Short days in fall
• trigger molting of brown fur and regrowth of
  white fur. Long days in
• early summer trigger molting of white fur and
  regrowth of brown fur.
• Proximate factor is photoperiod.
• 2. What is the advantage in turning white
  in winter and brown in
• summer?
• C. Example 2 - Why do humans and other animals
  develop a fever?

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Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• B. Example 1 - Why do snowshoe hares turn white
  in winter? Two questions
• 1. What happens environmentally
  physiologically to cause hares to
• lose their brown fur and grow white fur?
  Answer? Short days in fall
• trigger molting of brown fur and regrowth of
  white fur. Long days in
• early summer trigger molting of white fur and
  regrowth of brown fur.
• Proximate factor is photoperiod.
• 2. What is the advantage in turning white
  in winter and brown in
• summer? Answer? Camouflage helps
  individuals escape predation.
• C. Example 2 - Why do humans and other animals
  develop a fever?

77
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 1. What physiological factors cause fever
  to occur?
• 2. What is the advantage to an organism
  of developing a fever?

78
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 1. What physiological factors cause fever
  to occur? Answer?
• 2. What is the advantage to an organism
  of developing a fever?

79
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 1. What physiological factors cause fever
  to occur? Answer?
• Disease organisms produce a chemical and
  white blood cells
• produce another chemical that triggers
  hypothalamus to increase heat
• production. Proximate factor is
  cell-mediated immune response.
• 2. What is the advantage to an organism
  of developing a fever?
• Answer?

80
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 1. What physiological factors cause fever
  to occur? Answer?
• Disease organisms produce a chemical and
  white blood cells
• produce another chemical that triggers
  hypothalamus to increase heat
• production. Proximate factor is
  cell-mediated immune response.
• 2. What is the advantage to an organism
  of developing a fever?
• Answer? (FIG. 8) Used ectotherm (desert
  iguana) to test.

81
(No Transcript)
82
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 1. What physiological factors cause fever
  to occur? Answer?
• Disease organisms produce a chemical and
  white blood cells
• produce another chemical that triggers
  hypothalamus to increase heat
• production. Proximate factor is
  cell-mediated immune response.
• 2. What is the advantage to an organism
  of developing a fever?
• Answer? (FIG. 8) Used ectotherm (desert
  iguana) to test. Iguanas
• seek warmer environment (42C) when sick
  than when healthy
• (38C). Two groups infected with bacterium
  were placed in different
• laboratory environments.

83
(No Transcript)
84
Lecture 2 Variation and Adaptation

• IV. Proximate and Ultimate Factors
  (Explanations)
• C. Example 2 - Why do humans and other animals
  develop a fever?
• Two questions
• 2. What is the advantage to an organism
  of developing a fever?
• Answer? (FIG. 8) Used ectotherm (desert
  iguana) to test. Iguanas
• seek warmer environment (42C) when sick
  than when healthy
• (38C). Two groups infected with bacterium
  were placed in different
• laboratory environments. Only 25 survived
  at 38 but 80
• survived at 42. Fever greatly increased
  survival!

85
Photo Credits

• American yarrow (Achillea millefolium var
  lanulosa). (Left photo) www.life.umd.edu/.../PBI
  O/LnC/LCpublic2.html. (Right photo) eNature.
  National Wildlife Federation. enature.com/fieldgu
  ides.
• White water-buttercup (Ranunculus aquatilis).
  (Large photo) Lewis and Clark Herbarium Plants
  Collected by Lewis and Clark. Photo by Thomas
  Schoepke. www.plant-pictures.com. (Small photo)
  Wisconsin Botanical Information System. Photo by
  Robert W. Freckman. www.botany.wisc.edu/wisflora.
  
• Western gulls (Larus occidentalis). (1) Chicks.
  (2) Juvenile. (3) 2nd Winter. (4) Adult. All
  photos from www.geocities.com/tgrey41/Pages/Wester
  nGull.html.
• (Left) Herring gull (Larus argentatus). Bird
  Sites, Sights Sounds. Photo by Eva Casey.
  www.theworld.com/eva/birds/html. (Right) House
  sparrow (Passer domesticus). Birds of Britain.
  Photo by Christine Nichols. www.birdsofbritain.co
  .uk/bird-guide/house-sparrow.asp
• (Left) Northern gannet (Morus bassanus). Photo
  by John Short. www.bbc.co.uk/tyne/content.
  (Right) Red-legged partridge (Alectoris rufa).
  Photo by Pascal Dubois. Petit Bel
  Air-Villete-de-Vienne-Isere (38) FRANCE 7 sept.
  2002.
• Whiskered tree swift (Hemiprocne comata). Photo
  by Romy Ocon. www.pbase.com/liquidstone.
• Seen on www.birdwatch.ph/html/gallery.
• Snowshoe hare (Lepus americanus). (Left)
  www.hww.ca/hww2.asp?id103. (Upper right) Photo
  by Michael S. Quinton. www3.national
  geographic.com/animals/mammals. (Bottom right)
  Photo by R. Brocke. www.esf.edu/aec/adks/mammals/
  snowshoe_hare.htm.
• Desert iguana (Dipsosaurus dorsalis) (Left)
  Photo by Richard Seaman. www.richard-seaman.com/.
  ../index.html. (Right) Photo by Pete Zani.
  www.biol.lu.se/zoofysiol/Djurarticlar/Feber.html.