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What is Evolution? • What is Evolution? • A process of biological change over generations that makes descendants become gradually different from their ancestors • Charles Darwin gets much of the credit for the theory of evolution TO DO! • Look in your Biology book on pages 298-299 • Grab a partner and list each of the four names below and write a sentence or two describing how each person contributed to the theory of evolution. • • • • Carolus Linnaeus Georges Louis Leclerc de Buffon Erasmus Darwin (Charles’ grandfather) Jean-Baptiste Lamarck Carolus Linnaeus’s Ideas (A Swedish Botanist during the 1700s) • He put organisms into groups based on physical characteristics • He created the Linnaean system of classification has 7 levels: Kingdom, Phylum, Class, Order, Family, Genus, Species • He is also responsible for: binomial nomenclature—a 2 word system of naming (written in Latin because it is not used) Georges Louis Leclerc de Buffon’s Ideas: (A French Naturalist of the 1700s) • Said species shared ancestors instead of forming separately Erasmus Darwin (Charles’s grandfather) (An English doctor & poet born in 1731) • Said that living things are descended from a common ancestor • He suggested that more complex forms of life came from more simple ones • He did not believe in extinction, just in species evolving into something else Jean-Baptiste Lamarck’s Ideas: (A French Naturalist who made his theories known in 1809) • Organisms evolved towards being perfect and complex • Species do not become extinct, they just evolve • Adaptation is a result of change caused by environmental change • Organs and structures changed in regard to use or disuse and changes are passed on to offspring Charles Darwin • • • • 1809-1882 British naturalist Proposed the idea of evolution by natural selection Collected clear evidence using live organisms AND fossils to support his ideas Charles Darwin • Darwin traveled to many places to research his theories on evolution. • When he visited the Galapagos Islands he noticed a wide variety of traits among similar species. Example -- Darwin noticed that the island with short-necked turtles had vegetation lower to the ground while the island with the longnecked turtles had taller vegetation Video Galapagos Islands (on Safari) 1. All individuals in a population have variations. 2. Some of these variations allow individuals to successfully compete. 3. Those that “win” at competition are able to eat to survive. 4. The individual is able to reproduce and pass their variations on to their offspring. Darwin called this: Artificial Selection —when humans determine which traits are favorable and then breed organisms that show those traits Heritability – the ability of a trait to be passed down from one generation to the next Natural Selection – a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do others 4 Main Principles to the Theory of Natural Selection 1. Genetic Variation 2. Overproduction 3. Adaptation 4. Descent with modification 1. Genetic Variation Variations can: • Increase the fitness (ability to survive) to the environment • Increase the chance for reproduction/ survival & passing on genes • Be a product of evolution by natural selection Genetic variation refers to diversity in genes and can refer to differences between individuals or populations. Mutations and sexual reproduction are the main things that cause genetic variation. In order for the variation to continue the organism must compete, reproduce and feed successfully Example: size of moose’s antlers, coloring of a mouse 2. Overproduction While producing many offspring give an advantage of species survival the offspring also are in more competition for food/resources 3. Adaptions These are physical or behavioral changes in organisms that actually help some organisms survive better. Example: Panda’s wrist acts as thumb (see page 309 for picture) 4. Descent With Modifications This means that adaptive traits that help the organism survive will be passed on to the next generation and more of the organisms will show that helpful trait in each of the generations that follow after that. Check out this 10 minute clip about how some mice had a mutation in fur color that helped them evolve into two different populations of mice http://www.hhmi.org/biointeractive/making-fittest-natural-selectionand-adaptation Peppered Moth activity 3 TYPES OF ADAPTATIONS: 1.Behavioral 2.Physiological 3.Structural 1. Behavioral Involves the way an organism acts in response to an it’s environment Examples: birds migrate, bears hibernate, salmon swimming to spawning ground 2. Physiological Involves the function of a trait Examples: venom of snakes or the ink of octopus, etc. 3. Structural Involves the anatomy of an organism Examples: bird’s beak, horse's hoof, anteater snout, etc. “Survival of the Sneakiest” activity Evidence of Evolution • • • • • Fossils Geography Embryology Anatomy DNA Sequence new layers of rock cover older ones, creating a record over time fossils within layers show that a succession of organisms have populated Earth throughout a long period of time The fossils are lined up according to TIME Similarities and differences are noted between fossils GEOGRAPHICAL EVIDENCE • Different places have different plants, animals and climates even if they share similar ancestors • When Darwin visited the various islands on his voyage to the Galapagos islands he found that similar organisms had different traits that helped them survive in their particular environment. Example: finches on certain Galapagos islands have beaks of different sizes though they have the South American Finch as their common ancestor EMBRYOLOGICAL EVIDENCE • Similar embryological development in closely related species – all vertebrate embryos have similar structures at different stages of development All of these creatures have gill pouches as embryos This suggests a common ancestor that lived in the sea ANATOMICAL EVIDENCE Homologous Structures = similar shape, but different modern function Examples: Similar forelimb bone structures for human, cats, whales, & bats suggest they shared a common ancestor a long time ago Vestigal Structures = Remnants of organs or structures that had a function in an earlier ancestor (evidence of change over time) Examples: some snakes & whales show remains of the pelvis & leg bones of walking ancestors, eyes on blind cave fish, human tail bone Evolutionary Biology Today • Fossil evidence is still used • Molecular and genetic evidence supports fossil and anatomical evidence Example: 2006 fossil discovery of an early tetrapod links sea animals & land animals DNA Sequence Evidence DNA sequence analysis - The more related two organisms are, the more similar their DNA sequences will be Example: Giant Panda is more closely related to bears than raccoons Interactive Game: “Who Wants to Live a Million Years?” http://www.sciencechannel.com/games-andinteractives/charles-darwin-game.htm Evolution of Populations • Genetic variation in a population = lots of different traits in a certain group of animals or plants • The more variation, the better the chance that the species will survive Genetic variation is in the group’s gene pool …that is the combined genetic traits of all the individuals in that group Where does genetic variation come from? 1. Mutation – a change or mistake in the Genetic sequence/DNA 2. Genetic Recombination – New combinations of the genetic alleles from parents (Example parents might have genetic letters BB and bb but the daughter or son would have Bb…same letters, different order or “combination” A Type of Natural Selection: Sexual Selection Occurs when certain traits increase the success of sexual reproduction 1. Competition among males for a mate 2. When males display certain traits that attract females How do humans decide who they are attracted to??? How do you think cosmetic surgery or medicine effects natural selection in humans?? Factors That can Lead to Evolution • • • • • Genetic Drift Gene Flow Mutation Sexual Selection Natural Selection • We have already learned about mutations, sexual selection, and Natural Selection but what are genetic drift and gene flow???? Genetic Drift--The frequency that genetic traits show up by CHANCE (like a genetic lottery) Gene Flow--As individuals or small groups move between different populations, they can affect the genetic traits that begin showing up in the populations Isolated Populations When a population becomes “isolated” that means that they no longer mate with other populations Isolation can eventually cause populations to become different species over time Why does this occur?– not physically able to mate with other populations, behavioral differences, geographic separation, or their timing is simply “off” Species Can Affect Each Other • This happens in life…organisms compete for food with their neighbors or are predators/prey for certain other organisms nearby….In order to survive, they adapt Example: If you and your new college roommate both like Pizza Rolls but you only get one box a week and he hogs them all, maybe you would opt for frozen burritos after being hungry for a while! Clip on Galapagos Island Finches (13 minutes): http://youtube/n3265bno2X0 Hawaiian Birds Evolution Article and Questions Extinction • Background extinction – extinction that occurs in smaller amounts of species all the time but at a low rate • Mass Extinction – extinction that is more rare, often at a global level (example: mass extinction of dinosaurs) The History of Life Scientists can trace how organisms have evolved over the years by looking at the geologic time scale FYI! A wide variety of living organisms have inhabited Earth over millions of years Many species went extinct at different points in Earth’s history Human beings have only been around for the last 10,000 years 97% of all things have died out Quagga extinct1880 Passenger Pigeon extinct 1914 Javan Tiger extinct: 1979 The Golden Toad Evolution Flashcards & Activity: An Evolutionary Experiment