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Evolution Overview Evidence for Evolution A. Biogeography 1. Geographical distribution of species Evidence for Evolution B. Fossil Record 1. 2. Evolutionary transitions New forms appearing/disappearing Evidence for Evolution Transitional Forms Evidence for Evolution C. Comparative Anatomy 1. Anatomical similarities between species grouped in the same taxonomic categories Evidence for Evolution 2. Homologous structures a. Similarity in characteristics from common ancestor Evidence for Evolution Analogous structure 3. a. b. Look similar because of environment No common ancestor Evidence for Evolution Comparative Embryology D. 1. Closely related organisms go through similar stages in embryonic development Evidence for Evolution View comparative embryology Evidence for Evolution Molecular Biology E. 1. DNA, RNA, Protein Analysis, mitochondrial DNA Evolution is Descent With Modification Evolution only occurs when there is a change in gene frequency within a population over time. Beetles and Drought Beetles of a different color 1st Year 2nd Year Why are the beetles smaller the next year? Evolution or environmental influences? Why are there less green beetles the next year? Evolution or environmental influences? Basic Mechanisms of Evolutionary Change I. A. B. C. D. Mutation Migration Genetic Drift Natural Selection A. B. D. C. Genetic Variations II. Mutations (Genetic Variation) A. 1. 2. DNA copies incorrectly External influences Gene Flow (migration) B. any movement of genes from one population to another Sex (genetic shuffling) C. can introduce new gene combinations into a population Genetic Drift III. A. B. C. Some individuals leave more descendants Chance Founder effect Natural Selection IV. A. B. C. Variation in traits Differential reproduction Heredity D. Fitness how well an individual contributed its genes to the next generation Types of Natural Selection E. Stabilizing Selection Types of Natural Selection continued F. Directional Selection Types of Natural Selection continued G. Disruptive Selection Coevolution V. • two (or more) species reciprocally affect each other’s evolution Microevolution (You can see change) I. Evolution on a small scale within a single population A change in generation-to-generation gene frequency within a population. Detecting Micro-evolutionary Change WHY? Mechanisms of micro-evolutionary change A. 1. 2. 3. 4. Mutation Migration Genetic Drift Natural Selection Example of Microevolution The size of the sparrow (originally introduced in the East in 1852…) Why are sparrows now larger in the north? http://evoled.dbs.umt.edu/images/modes.gif Speciation II. a lineage-splitting event that produces two or more separate species A. Species a group of individuals that actually or potentially interbreed in nature. •these happy face spiders look different, but since they can interbreed, they are considered the same species: Theridion grallator. The scene: a population of wild fruit flies minding its own business on several bunches of rotting bananas, cheerfully laying their eggs in the mushy fruit... Disaster strikes: A hurricane washes the bananas and the immature fruit flies they contain out to sea. The banana bunch eventually washes up on an island off the coast of the mainland. The fruit flies mature and emerge from their slimy nursery onto the lonely island. Has speciation occurred yet??? Types of Reproductive Isolation (behavioral, geographic, temporal, mechanical… pre/post zygotic??? So we meet again: When another storm reintroduces the island flies to the mainland… what will happen now? Prezygotic Barriers B. 1. 2. 3. 4. 5. 6. Prevents mating and formation of zygotes Habitat Isolation Behavioral Isolation Temporal Isolation Mechanical Isolation Gametic Isolation Geographic Isolation Postzygotic barriers C. 1. 2. 3. Prevents zygotes from developing into fertile offspring Reduced hybrid viability Reduced hybrid fertility Natural selection Macroevolution III. evolution of groups larger than an individual species. encompasses the grandest trends and transformations in evolution, such as the origin of mammals and the radiation of flowering plants The basic evolutionary mechanisms— mutation, migration, genetic drift, and natural selection— can produce major evolutionary change if given enough time. The History of Evolutionary Thought A. James Hutton 17261797 1. 2. Geologist Gradualism = Profound change is the cumulative product of slow but continuous process The History of Evolutionary Thought Geology The scientific study of the origin, history, and structure of the earth Geologic Time Scale Used to represent evolutionary time Geology The History of Evolutionary Thought B. Charles Lyell (17971875) Geologist Uniformitarianism 1. 2. Geological processes have not changed throughout Earth’s history The History of Evolutionary Thought C. Jean Baptiste Lamark (1744-1829) Proposed theory of evolution 1. a. b. Change Through Use and Disuse Organisms Driven to Greater Complexity The History of Evolutionary Thought D. Thomas Malthus (17661834) 1. 2. Economist Population Growth vs. the Food Supply The History of Evolutionary Thought E. Charles Darwin (1809-1882) 1. 2. 3. Naturalist 1831-1836 voyage on H.M.S. Beagle Mission: chart south american coast line F. Darwin’s Finches 1. 2. 3. 4. 5. Galapagos formed from volcanoes (young) Species live nowhere else Resemble South American Different islands, different environments Today – each island has own species 6. Finch ancestors came from South America a. “islands had been colonized by plants and animals strayed from mainland and then diversified” 7.Different islands, different environments a. Adaptation G. Darwin’s Theory of Natural Selection 1. Obs. #1: Population size would increase exponentially if all offspring reproduced successfully 2. Obs. #2: Populations tend to remain stable in size 3. Obs. #3: Environmental resources are limited a. Inf. #1: more individuals = struggle for resources. Only a fraction of offspring survive 4. Obs. #4: Individuals of a population vary in characteristics 5. Obs. #5: Much of variation is heritable b. Inf. #2: Survival is not random but depends on heredity. Individuals most fit for environment will produce more offspring Inf. #3: unequal ability of individuals to survive and reproduce = gradual change in a population, c. with favorable characteristics accumulating over generations H. Key Subtle Points 1. 2. 3. Individuals don’t evolve, populations evolve Adaptations an organism acquires from its own actions is different from inherited adaptations that evolve in a population over time Specifics of natural selection are situational Origin of Primates Lemurs 55 mya Tarsiers 50 mya … check out the fingers…and massive eyes New World Monkey (note tails, side facing nostrils) 35 mya, all arboreal Woolly spider monkey golden lion tamarin Old World monkey: ~22 mya (down ward facing nostrils, no prehensile tail) Some arboreal Some ground dwelling Macaque Monkey Gibbon (ape not a monkey) ~15 mya Hominoids: larger brains than monkeys no tails smaller ranges Hominoid: (ape) Orangutan diverged ~12 mya Largest arboreal hominoid Vegetarian Gorilla (~8 mya) largest ape- live in groups up to 20 individuals Knuckle walkers Can walk upright Shorter legs than arms Sexual dimorphism More closely related to humans and chimps than other apes Pan paniscus, Pan troglodytes… chimps… (diverged ~5 mya) Bonobos chimps (dwarf chimpanzees) (female dominate society) regular chimpanzees (male dominate society) Human vs. Gorilla Hominin family tree… http://www.youtube.com/watch?v=w1Lu4VggDH0 Laetoli footpath Lucy 3.6 mya Evidence of bipedalism Homo sapiens neanderthalensis vs Homo sapiens sapiens http://www.youtube.com/watch?v=doF4sNr Qtmg&feature=related Out of Africa… modern humans