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Changes /Adaptations Over Time Species • A group of organisms that share traits (characteristics) that may be similar. • They also have to be able to reproduce Evolution • Change in inherited characteristics of a species over time. Basic Concepts of Natural Selection • Individual living things are different from each other. This is called variation. • Variation is important because without it, populations cannot evolve over time. • Living things produce more offspring than can survive, and many that survive do not reproduce. • Living things compete for limited resources, such as food and shelter. Theories • Scientific theory: well-tested concept or explanation not proven – Jean Baptiste de Lamarck – Charles Darwin Lamarck Lamarck's Theory of Evolution: Darwin was not the first person to propose a theory of evolution. In the early 1800s, a wellknown French naturalist named Jean-Baptiste Lamarck also developed a theory of evolution. •He introduced the idea that the environment caused changes in animals and these changes were inherited by the animals' offspring. •changes in an organism during its lifetime could be passed on to its offspring. •if an organism that used certain organs more than others, then the organ used the most would evolve. • For example, Lamarck thought that giraffes could stretch their necks to feed on the leaves of tall trees. These giraffes would have offspring with long necks. • He called this the hypothesis of use and disuse. • This idea is often called "the inheritance of acquired characteristics," or "soft inheritance," and it is now known to be incorrect. • Changes in an organism cannot be passed onto its offspring unless they are controlled by genes. Charles Darwin H.M.S. Beagle Darwin • Darwin observed that species of finches on islands off the coast of South America looked similar to a mainland species of finches • He hypothesized that plants and animals on the islands originally came from South America http://www.pbs.org/wgbh/nova/evolution/explore-galapagos.html • Darwin reasoned that members of a population best able to survive and reproduce will pass their traits to the next generation; over time • Resulting in a different (separate) species • Darwin say similarities but could not explain WHY they existed. Darwin • His hypothesis became known as a theory of evolution by natural selection- organisms with traits suited for the environment will more likely survive and reproduce http://www.pbs.org/wgbh/nova/evolution/darwin-never-knew.html http://videos.howstuffworks.com/science/evolution-of-life-videosplaylist.htm#video-29147 • Fossils- the preserved remains of an organism that had died long ago. • Darwin saw the fossil bones of organisms that had died and was puzzled by some of them, such as the fossil bones that resembled living sloths. These were much larger than those that were still living. He wandered what had happened to the giant creatures of the past. Fossils • Fossil records show extinct organisms • Showed similarities to living organisms • Hypothesized current organism descended from the fossilized organism http://videos.howstuffworks.com/discovery-health/4911-100-greatest-discoveries-evolution-video.htm Adaptations • A trait that helps an organism survive and reproduce. – Ex finches beaks-help in obtaining food – Coloring Natural Selection • Factors that affect the process: – Overproduction – Variation – Competition – Selection – Environmental Change – Genes and Natural Selection Variation • An inherited trait that makes an individual different from other members of its species; an adaptation is a variation that makes an organism better suited to its environment. • 1. Environmental factors can cause changes in source of genes. • 2. Geographic isolation can make two populations so different they become different species. • http://www.pbs.org/wnet/nature/lessons/the-birds-and-the-beaks/video-segments-extraordinarybirds/1481/ Variety Speed of Evolution • Two models that explain the speed of evolution – Gradualism – Punctuated equilibrium Speed of evolution • Gradualism – Slow, ongoing process – Change may take place through a slow but continuous process • Punctuated equilibrium – Gene mutation can result in a new species in a short period of time