The Origin of Species and The
Shape of Evolution
 How do existing species give rise to new




species?
How do the processes of evolution contribute
to the origin of new species?
How do species diversify?
What does the “family tree” of species look
like?
Are there any challenges to the idea of
evolution? Are they valid?
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The Origin of Species and The
Shape of Evolution
 New Species
 The origin of new species is the evolution of any
differences between populations that prevent the
production of fertile offspring.
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2
The Origin of Species and The Shape
of Evolution
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 Reproductive Isolating Mechanism
 Any difference that prevents the production of fertile
offspring between members of two populations.
 Hominins
 Modern human beings and our ancestors, generally
defined as the primates who habitually walk erect.
 Speciation
 The evolution of a new species.
 Macromutations
 Mutations with extensive and important phenotypic
results.
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The Origin of Species and The
Shape of Evolution
 Adaptive Radiation: The Evolution of Life’s
Diversity
 For a potential new species to persevere, it must
survive the adaptive trials of natural selection.
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 Adaptive Radiation
 The evolution and spreading out of related species
into new niches.
 Generalized
 Here, species that are adapted to a wide range of
environmental niches.
 Specialized
 Here, species that are adapted to a narrow range
of environmental niches.
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 Nocturnal
 Active at night.
 Prosimian
 A primate with primitive features, most closely
resembling the ancient primates.
 Diurnal
 Active during the day.
 Arboreal
 Adapted to life in the trees.
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The Origin of Species and The
Shape of Evolution
 The Shape of the Family Tree
 The evolution of life on earth cannot be depicted
as a ladder or a chain, nor is it a gracefully
branching tree.
 Instead, it is a “luxuriant bush,” more complex
than we will probably ever know.
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The Origin of Species and
The Shape of Evolution
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 Darwinian Gradualism
 The view, held by Darwin, that evolution is slow
and steady with cumulative change.
 Microevolution
 Evolutionary change within a single species
through time.
 Macroevolution
 The branching of new species from existing
species.
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 Oscillating Selection
 Adaptive variation around a norm, rather than in
one direction, in response to environmental
variation in a species’ habitat.
 Punctuated Equilibrium
 The view that species tend to remain stable and
that evolutionary change occur fairly suddenly
through the evolution of new species branching
from existing ones.
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The Origin of Species and The
Shape of Evolution
 Evolution Questioned: The Pseudoscience of
“Scientific Creationism”
 Scientific creationism is a pseudoscience, a
testable set of ideas that even in the face of
contrary evidence is accepted on faith.
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 Pseudoscience
 Scientifically testable ideas that are taken on faith,
even if tested and shown to be false.
 Scientific Creationism
 The belief in a literal biblical interpretation regarding
the creation of the universe, with the connected belief
that this view is supported by scientific evidence.
 Intelligent Design
 The idea that an intelligent designer played a role in
some aspect of the evolution of life on earth, usually
the origin of life itself.
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The Origin of Species and The
Shape of Evolution
 Summary
 The evidence of evolution is overwhelming. We
are still examining the specific details of
evolutionary theory, but the idea of evolution and
our knowledge of the essential processes involved
are hypotheses that have passed numerous
scientific tests and failed none.
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