WHAT IS EVOLUTION? Evolution is the gradual change in a species over time. A species is a group of similar organisms that can mate with each other and produce fertile offspring. Theory of Evolution: What is the difference between a theory, hypothesis, and a law? CHARLES DARWIN – 1809-1882 • English naturalist • Developed the theory of evolution by natural selection • Observed many species and fossils • Traveled around the world on the ship Beagle – Famous in the Galapagos Islands • Why did some species survive while others became extinct? Charles Darwin – Galapagos Islands What did Darwin observe on the Galapagos Islands that led him to propose his theory of evolution? EVIDENCE OF EVOLUTION • Adaptations: A trait that helps an organism survive and reproduce. – Mimicry – Camouflage – Beak shape/size . Adaptations…Camouflage what do you see? WHAT IS NATURAL SELECTION? Natural Selection is the process by which individuals that are better adapted to their environment are more likely to survive and reproduce that other members of the same species. Factors that affect the process of natural selection: ~ Overproduction ~ Competition ~ Variations: Any difference between individuals of the same species. . Natural Selection Over a long period of time, natural selection can lead to evolution. Helpful variations gradually accumulate in a species, while unfavorable ones disappear. Explain why variations are needed for natural selection to occur. How Do New Species Form? • A new species can form when a group of individuals remains separated from the rest of its species long enough to evolve different traits. • Speciation - Geographic Isolation - Reproductive Isolation ---------------- Geographic Isolation Continued… Continental Drift – Motion of continents about Earth's surface on plates of crust floating on the hot mantle. OTHER EVIDENCE OF EVOLUTION • FOSSILS • EARLY DEVELOPMENT (Embryos) • ANATOMY (Body Structure) – HOMOLOGOUS STRUCTURES • SIMILARITIES IN DNA Homologous Structures – similar structures that related species have inherited from a common ancestor. FOSSIL RECORD Fossil – The preserved remains or traces of an organism that lived in the past. How Do Fossils Form? Most fossils form when organisms that die become buried in sediments (particles of soil and rock). Others can be preserved in ice, tar pits, or sap. FOSSIL RECORD The fossil record refers to the millions of fossils scientists have collected. What Do Fossils Reveal about extinct species? ~ How it looked ~ How it behaved ~ How it evolved (related species) Group of jellyfish fossils has been uncovered in Wisconsin, US How Fast Does Evolution Occur? • Gradualism • Punctuated Equilibria ~ The theory that evolution ~ The theory that species evolve occurs slowly but steadily. during short periods of rapid change Combining The Evidence • Branching Tree – A diagram that shows how scientists think different groups organisms are related. Geologic Time Scale Earth’s history is organized into 4 eras: • Precambrian • Paleozoic • Mesozoic • Cenozoic Some Questions to Ponder… • Human evolution so far… • 10,000 years from now… – Where will humans live? – How will our environment change? – What will the world look like? – How Will The Forces of Evolution Work On Our Species?