Transcript Descent with Modification

Chapter 22
Descent with Modification
Chapter 22
Descent with Modification
Darwin’s context:
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier – fossils and extinction
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier – fossils and extinction
•Lyell –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier – fossils and extinction
•Lyell – modern geology
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier – fossils and extinction
•Lyell – modern geology
•Mendel –
Chapter 22
Descent with Modification
Darwin’s context:
•Linnaeus – classification (taxonomy)
•Hutton – gradual geological change
•Lamarck – species can change
•Malthus – population limits
•Cuvier – fossils and extinction
•Lyell – modern geology
•Mendel – genetic inheritance.
Chapter 22
Descent with Modification
Lamarck’s theory of evolution (1809)
•Fossil record shows lines of descent
•Use and disuse of body parts
•Inheritance of acquired characteristics.
Chapter 22
Descent with Modification
Chapter 22
Descent with Modification
Chapter 22
Descent with Modification
Chapter 22
Descent with Modification
Observation 1:
For any species, population size would
increase exponentially if all individuals that
are born reproduced successfully
Chapter 22
Descent with Modification
Observation 1:
For any species, population size would
increase exponentially if all individuals that
are born reproduced successfully.
Observation 2:
Nonetheless, populations tend to remain
stable in size, except for seasonal
fluctuations
Chapter 22
Descent with Modification
Observation 1:
For any species, population size would
increase exponentially if all individuals that
are born reproduced successfully.
Observation 2:
Nonetheless, populations tend to remain
stable in size, except for seasonal
fluctuations.
Observation 3:
Resources are limited.
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Descent with Modification
Inference 1:
Production of more individuals than the
environment can support leads to a struggle
for existence among individuals of a
population, with only a fraction of their
offspring surviving each generation.
Chapter 22
Descent with Modification
Observation 4:
Members of a population vary extensively in
their characteristics. No two individuals are
exactly alike
Chapter 22
Descent with Modification
Observation 4:
Members of a population vary extensively in
their characteristics. No two individuals are
exactly alike.
Observation 5:
Much of this variation is heritable.
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Descent with Modification
Inference 2:
Survival depends in part on inherited traits.
Individuals whose inherited traits give them a
high probability of surviving and reproducing
in a given environment have higher fitness
and are likely to leave more offspring than
less fit individuals.
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Descent with Modification
Inference 3:
This unequal ability of individuals to survive
and reproduce will lead to a gradual change in
a population, with favorable characteristics
accumulating over generations.
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Descent with Modification
Natural Selection:
Chapter 22
Descent with Modification
Natural Selection:
•The differential success in reproduction
among individuals that vary in their heritable
traits
Chapter 22
Descent with Modification
Natural Selection:
•The differential success in reproduction
among individuals that vary in their heritable
traits.
•Over time, natural selection can increase the
adaptation of organisms to their environment
Chapter 22
Descent with Modification
Natural Selection:
•The differential success in reproduction
among individuals that vary in their heritable
traits.
•Over time, natural selection can increase the
adaptation of organisms to their environment.
•If an environment changes over time, or if a
population moves to a new environment,
natural selection may result in adaptation to
these new conditions
Chapter 22
Descent with Modification
Natural Selection:
•The differential success in reproduction
among individuals that vary in their heritable
traits.
•Over time, natural selection can increase the
adaptation of organisms to their environment.
•If an environment changes over time, or if a
population moves to a new environment,
natural selection may result in adaptation to
these new conditions, sometimes giving rise
to new species.
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Descent with Modification
Evidence:
•Evolution in action today
•Anatomical homologies
•Molecular homologies
•Biogeography
•The fossil record.
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Descent with Modification
Some key points:
Chapter 22
Descent with Modification
Some key points:
Individuals do not evolve;
populations evolve over
generations
Chapter 22
Descent with Modification
Some key points:
Evolution does not move
towards a goal
Chapter 22
Descent with Modification
Some key points:
Adaptations are always based
on existing structures
Chapter 22
Descent with Modification
Some key points:
Events in the past are inferred,
but natural selection and descent
with modification are observable
events happening today in the
world and in the laboratory.
Chapter 22
Descent with Modification
Some key points:
Evolution is “just a theory” like
Newton’s theory of gravitation.
Chapter 22
Descent with Modification
Some key points:
Evolution is “just a theory” like
Newton’s theory of gravitation.
Both make sense of massive
amounts of data.
Chapter 22
Descent with Modification
Some key points:
Evolution is “just a theory” like
Newton’s theory of gravitation.
Both make sense of massive
amounts of data.
Both make accurate predictions.
Chapter 22
Descent with Modification
Some key points:
Evolution is “just a theory” like
Newton’s theory of gravitation.
Both make sense of massive
amounts of data.
Both make accurate predictions.
Both are subject to constant
questioning and revision.
.