Chapter 24 - Class Notes CHAPTER 24 ORIGIN OF SPECIES...

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Class Notes Chapter 24: Origin of Species 9.10.09 CHAPTER 24: ORIGIN OF SPECIES Overview: That “Mystery of Mysteries” In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth Speciation, the origin of new species, is at the focal point of evolutionary theory Evolutionary theory must explain how new species originate and how populations evolve Microevolution consists of adaptations that evolve within a population, confined to one gene pool Macroevolution refers to evolutionary change above the species level Concept 24.1: The biological species concept emphasizes reproductive isolation Species is a Latin word meaning “kind” or “appearance” Biologists compare ________________________________ The biological species concept states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations Gene flow between populations holds the phenotype of a population together Reproductive Isolation Reproductive isolation is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring Hybrids are the offspring of crosses between different species Reproductive isolation can be classified by whether factors act before or after fertilization Prezygotic barriers block fertilization from occurring by: Impeding different species from attempting to mate Preventing the successful completion of mating Hindering fertilization if mating is successful Habitat isolation : Two species encounter each other rarely, or not at all, because they occupy different habitats,
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This note was uploaded on 11/12/2009 for the course BIO 1510 taught by Professor Unknown during the Fall '07 term at Georgia Tech.

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Chapter 24 - Class Notes CHAPTER 24 ORIGIN OF SPECIES...

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