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Evolution
The change in the genetic makeup of a
population over time is evolution
Darwin and the Voyage of The Beagle
Biogeography: the geographic distribution of
species
Species tend to be more closely related to other
species from the same area rather than species
with a similar way of life but living in a different
area
The historical context of Darwin’s life and ideas
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Linnaeus – taxonomy
Cuvier – paleontology
Hutton – geology
Lyell – geology
Lamarck – propose an alternative theory of
evolution
• Malthus – economist
The Origin of Species
Evolution by natural
Selection
Descent with
Modification
Principle of Natural Selection
• There are more individuals than the environment can
support, leading to a struggle for existence, with only a
fraction of offspring surviving each generation
• Survival of individuals is not random but depends on
their fitness
• These traits are heritable and are passed on from one
generation from the next
• The unequal ability of individuals to survive and
reproduce will lead to a gradual change in population,
with favorable characteristics accumulating over the
generations
Important Terms
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Fitness and reproductive success
Relative fitness
Adaptation
Heritability
Genetic variability
mutation
• Adaptive radiation: process in which
organisms diversify rapidly into new forms
• Population bottlenecks: sharp reduction in the
size of populations
• Mutation: permanent change in DNA
sequence
Selection In Action
• Peppered moths
• Darwin’s finches
• Antibiotic-resistant bacteria
Do Now:
• Which of the following is not an observation or
inference on which natural selection is based?
(a) There is heritable variation among individuals
(b) Poorly adapted individuals never produce offspring
(c) There is a struggle for limited resources and only a fraction of
offspring survive
(d) individuals whose characteristics are best suited to the environment
generally leave more offspring than those whose characteristics are
less well suited
(e) organisms interact with their environments