LECTURE 9 Evolution, Speciation, and Extinction
I. Evolution and Speciation A. Some Basic Genetics B. Natural Selection C. Isolation and Speciation II. Geography and Evolution III. Extinction
LECTURE 9 I. Evolution and Speciation
Evolution: Genetically controlled changes in physiology, anatomy, and behavior that occur to a species over time.
Speciation: The development of two or more genetially differentiable species from a single common ancsetor.
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DNA
LECTURE 9 I. Evolution and Speciation
Alleles and polymorphism.
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Natural Selection: The process by which the genes for genetically controlled traits become more common in a population over time because individuals with those traits are reproductively more successful than other individuals.
Charles Darwin Alfred Russel Wallace (1809-1882) (1823-1913)
LECTURE 9 I. Evolution and Speciation Isolation and Speciation:
3 LECTURE 9 I. Evolution and Speciation Isolation and Speciation:
LECTURE 9 I. Evolution and Speciation Isolation and Speciation:
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LECTURE 9 I. Evolution and Speciation
Genetic Drift: Stochastic changes in the genetic composition of a population that occur over time as new genes arise via mutation and other genes are lost through chance processes. (ex. Bottleneck and Founder Effect)
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Founder Effect:
LECTURE 9 II. Geography and Evolution
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Adaptive Radiation: The development of many species from a single founding species.
LECTURE 9 II. Geography and Evolution
Convergent Evolution: The development of similar morphological or physiological traits in unrelated species living in geographically separated regions that have similar environments.
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Coevolution: Two unrelated species evolve traits that are tied to their interactions.
LECTURE 9 II. Extinction
Extinction: The loss of all individuals in the population of a given species, genus, family, or order.
Ex. Local Extinction
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Ex. Global Extinction
LECTURE 9 II. Extinction
Trophic Cascade
9 LECTURE 9 Mass Extinctions: II. Extinction
Extinction of megafauna Extinction of marine mammals
Extinction of dinosaurs
Extinction of 50-90% plants and animals
Extinction of 50% animals
LECTURE 9 II. Extinction
What factors contribute to extinction? • Complex behavioral, physiological, or morphological adaptations • Species that are large in size • Predators • Small population size • Confined to a small geographic area
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