Charles Darwin 1809-1882 The Father of Evolution Charles Darwin Born in 1809, Shrewsbury, England Naturalist Studied Medicine Degree in Theology Buried in Westminster Abbey Darwin’s Theory of Evolution • Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. • A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world. Ideas that shaped Darwin’s Thinking • James Hutton: • 1795 Theory of Geological change – Forces change earth’s surface shape – Changes are slow – Earth much older than thousands of years Ideas that Shaped Darwin’s Thinking • Charles Lyell • Book: Principles of Geography • Geographical features • can be built up or torn down Darwin thought if earth changed over time, what about life? Lamarck’s Theory of Evolution Tendency toward Perfection(Giraffe necks) • Use and Disuse (bird’s using forearms) • Inheritance of Acquired Traits Population Growth • Thomas Malthus- • 19th century English economist If population grew (more Babies born than die) – Insufficient living space – Food runs out – Darwin applied this theory to animals Another influential scientist • Botanist • Contribution: – Essay described evolution by natural selection Alfred Russel Wallace 1823 - 1913 Publication of Orgin of Species • Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia • Gave Darwin the drive to publish his findings Voyage of Beagle • Dates: February 12th, 1831 • Captain: Charles Darwin • Ship: H.M.S. Beagle • Destination: Voyage around the world. • Findings: evidence to propose a revolutionary hypothesis about how life changes over time Row, row, row your boat! • Voyage of H.M.S. Beagle – 5 year unpaid voyage – Darwin studied plants, animals, collected fossils – Found fossils of extinct animals that were similar to modern species. On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America. This voyage lasted from 1831 to 1836. Many of Darwin’s conclusions were based on observations of wildlife in the Galapagos Islands. The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean, directly on the equator. “Galapagos” means turtle. The Galapagos Island • The smallest, lowest islands were hot, dry, and nearly barren-Hood Islandsparse vegetation • The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation. Animals found in the Galapagos • Land Tortoises • Darwin Finches • Blue-Footed Booby • Marine Iguanas Darwin noticed there were several types of finches on these islands. In particular, Darwin observed something odd about the finches: they all looked like a bird he had seen on the South American continent. In all, there were 13 types of finches, some species being confined to only one island. The most distinct difference among finch species is their beaks, which are adapted for the specific diets available on the islands. Darwin wondered if the birds and other animals had been created to match their environment, why didn’t these birds look like the birds of the African continent, since the environments of both the Galapagos and Africa were similar. Darwin guessed that some of the birds from South America migrated to the Galapagos. Once on the islands, the birds must have changed over the years. large ground finch woodpecker finch cactus finch This would explain the numerous species of birds present. G. fortis G. fuliginosa Camarhynchus pauper Cactospiza pallida G. magnirostris G. scandens C. psittacula Cacts Finch (nectar,eeds, blood) C. heliobates C. pauper Woodpecker-like Finch (seeds G. conirostris & insects) Geospiza difficilis Insect-eating Finch Platyspiza crassitrostris Seed-eating Finch Vegetarian Finch Ground Finch Certhidea olivacea & C. Fusca Tree Finch Warbler Finch This tree has how many major branches? PHYLOGENIC TREE: A diagram showing the evolutionary history of a species of an animal. The Journey Home • Darwin Observed that characteristics of many plants and animals vary greatly among the islands • Hypothesis: Separate species may have arose from an original ancestor Living Organisms and Fossils • Darwin collected the preserved remains of ancient organisms, called fossils. • Some of those fossils resembled organisms that were still alive today. Living Organisms and Fossils • Others looked completely unlike any creature he had ever seen. • As Darwin studied fossils, new questions arose. – Why had so many of these species disappeared? – How were they related to living species? Fossils TWO TYPES OF EVOLUTION: Convergent Evolution: process by which unrelated species become similar as they adapt to similar environments. Divergent Evolution: formation of new species from an existing species adapting to new environments. What type of evolution is a phylogenic tree? After returning from the Galapagos and studying all the different types of plants & animals. Darwin concluded new concepts of change…. Darwin called this… which means (change in species over time) Darwin extended these principles to biology, which helped him form his theory of… …or Survival of the Fittest. Natural Selection & Artificial Selection • Natural variation--differences among individuals of a species • Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful. Evolution by Natural Selection • The Struggle for Existence- members of each species have to compete for food, shelter, other life necessities • Survival of the Fittest-Some individuals better suited for the environment Natural Selection • Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment Five basic components of 1. All species have genetic variation. Every species is different, even within itself. Look around you…are you all the same? 2. The environment presents challenges to survival. There is a constant struggle for survival. Examples are: Drought Fires Floods Snowstorms Hurricanes Tornadoes Other natural disasters 3. Organisms produce more offspring than can survive. Competition exists WITHIN and AMONG species. Within a Species Among a Species food food space space mates 4. Individuals that are fit to their environment leave more offspring than those who aren’t. Darwin’s definition of fitness: an organism which has successfully adapted to its environment Organisms who possess favorable traits will leave more offspring. In other words, he who spreads the most genes wins! 1st 5. Characteristics of fit individuals increase in a population over time. Over time, genes for less favored characteristics will be eliminated from the gene pool. Example: giraffes and their long necks. Therefore Darwin’s contributions: Provided evidence that species evolve In 1859, he proposed the Theory of Natural Selection to explain evolution (Survival of the fittest) Over time, change within species leads to the replacement of old species by new species as less successful species become extinct. Some evidence from fossils may prove that species on Earth have evolved from ancestral forms that are extinct. (species that have disappeared permanently.) What is a species? One or more populations of individuals that can interbreed, producing fertile offspring. Speciation is the process by which new species are formed over time. Equus, the modern horse, evolved from the dog-sized Hyracotherium. Notice it evolved from a four-toed front foot to the one-toed front foot of the modern horse.