McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved

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?

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved 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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved 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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved 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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved 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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved definitions  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.

McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All Rights Reserved 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.