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Slide 2 studied medicine at Edinburgh University (1825-1827) where the sight of blood and surgery without anesthetics repulsed him studied to become a clergyman at Cambridge University (1827-1831) born in Shrewsbury, England, in 1809 Slide 3 After Cambridge, Charles was recommended for a surveying trip on the HMS Beagle. He sailed aboard the Beagle for 5 years, working as a naturalist. Slide 4 This voyage lasted from 1831 to 1836. The Beagle sailed around the world. Slide 5 At the time Darwin made his trip, the majority of people believed the Earth and all of its forms of life had been created only a few thousand years in the past. Slide 6 People also believed in fixity of species; in other words, species never changed. After careful observation and study of new scientific discoveries, Darwin began to think otherwise. People also believed that the Earth had not changed during those few thousand years. The first dinosaur to be described scientifically was Megalosaurus by William Buckland in 1824. Slide 7 Darwin was influenced by geologist James Huttons writings that described geologic forces he thought had changed and were still changing the earth. Hutton proposed that the Earth had to be much more than a few thousand years old. The Father of Geology Slide 8 Darwin was also influenced by geologist Charles Lyell who wrote Principia Geologica. Lyells book proposed that tremendous geologic processes had shaped the Earth such as seen in volcanoes active in the present. Slide 9 On the voyage, Darwin noticed that everywhere he went, the animals and plants differed vastly. Patterns in the species suggested that the species had changed over time and had given rise to new and different species. Slide 10 The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean, directly on the equator. Many of Darwins conclusions were based on observations of wildlife in the Galapagos Islands. Galapagos means turtle. Slide 11 What it must have been like to be Darwin Darwin noticed on these islands, there were several types of finches. Slide 12 In particular, Darwin observed something odd about the finches: they all looked like a bird he had seen on the South American continent. Slide 13 Darwin wondered if the birds and other animals had been created to match their environment, why didnt these birds look like the birds of the African continent, since the environments of both the Galapagos and Africa were similar. Slide 14 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. Slide 15 This would explain the numerous species of birds present. woodpecker finch cactus finch large ground finch Slide 16 Darwin called this or (change in species over time) Darwin concluded: Each species has descended, with changes, from other species over time. Descent With Modifications Slide 17 Malthus was a British social scientist who made these observations about humans: People have more children than are able to survive. There are built-in population checks: disease, famine, and war. Darwin based his theory on his own observations and the writings of Thomas Malthus. Slide 18 Darwin extended these principles to biology, which helped him form his theory of or Survival of the Fittest. Slide 19 Five basic components of Slide 20 1. All species have genetic variation. Every species is different, even within itself. Look around youare you all the same? Slide 21 2. Organisms produce more offspring than can survive. Many that survive do not produce offspring. The female green sea turtle lays a clutch of about 110 eggs. She may lay several clutches. It is likely that less than 1% of the hatchlings will ever reach sexual maturity. Slide 22 2. Since more organisms are produced than can survive, there is competition (struggle for existence). Competition exists WITHIN and AMONG species. food Within and Among Species for And Within a Species for water mates shelterspace Slide 23 The constant struggle for survival is affected by short-term natural disasters. (drought, fires, floods, snowstorms, hurricanes, and tornadoes) The constant struggle for survival is also affected by long-term changes in the environment. (ice ages, biome shifts, etc) Slide 24 3. Survival of the fittest Some organisms are more suited to their environment as a result of variations in the species. the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptations. Fitness: the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptations. He who spreads the most genes wins! 1st Individuals that are fit to their environment survive and leave more offspring than those who arent. Slide 25 4. Descent with modification: Living species today are descended with modifications from common ancestral species that lived in the past. Over time, genes for less favored characteristics will be eliminated from the gene pool. Example: giraffes and their increasingly longer necks. Characteristics of fit individuals increase in a population over time. Slide 26 Natural Selection: Survival of the Fittest the variation exists first. An adaptation is any inherited characteristic (a genetic variation) that can increase an organisms chance of survival. the environment changes. a variation may give an advantage to survive environmental change. An organism does not change because of need or desire to survive. The organism either already has the variation that enables it to survive or it dies. Slide 27 As the environment changes, organisms must have variations that allow them to survive (adapt) to those changes or die If an entire population of a species cannot adapt, that species becomes extinct. Slide 28 There have been at least 5 MASS extinctions during Earths history where a huge % of the living species were destroyed At least one of these has been attributed to meteor impact and its consequences. Slide 29 Davis, Donald E. Meteor Impact. (Also public domain from NASA.) No date. Online image with permission. Dinosaurs and Their Extinction. June 10, 2004. Snow Alaska. No date. Online image. Public Domain. Mineral Management Service. June 10, 2004. GeekPhilospher.com Allosaur. No date. Online image. Public Domain. Dinosaur National Monument. National Park Service. June 10, 2004. http://www.nps.gov/dino/index.htm