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. 1 LECTURE 9 I. Evolution and Speciation DNA LECTURE 9 I. Evolution and Speciation Alleles and polymorphism. 2 LECTURE 9 I. Evolution and Speciation 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: 4 LECTURE 9 I. Evolution and Speciation Isolation and Speciation: 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) 5 LECTURE 9 II. Geography and Evolution Founder Effect: LECTURE 9 II. Geography and Evolution 6 LECTURE 9 II. Geography and Evolution 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. 7 LECTURE 9 II. Geography and Evolution 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 8 LECTURE 9 II. Extinction 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 10.