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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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

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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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