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Transcript
Darwin, Wallace, & Natural Selection • https://youtu.be/XOiUZ3ycZwU Unit 6 Life Over Time I. Theory of Natural Selection https://youtu.be/0SCjhI86grU A. Darwin 1. Naturalist aboard the ship HMS Beagle 2. Collected many different species and fossils 3. Visited the Galapagos Islands where he realized that species change over time due to the environment 4. evolution= refers to the process by which populations change over time 5. population= all of the individuals of a species that live in an area at the same time 6. species= can mate and have fertile offspring B. Darwin noted differences among species 1. Darwin was amazed that there were so many different types of finches on different islands and mainland South America • the beaks would be different because of the different available food 2. The birds that had the beaks with the traits that could obtain the most food survived, reproduced, and passed their successful genes on C. Artificial Selection 1. artificial selection= humans select plants or animals for breeding based on desired traits wanted in the offspring 2. Darwin observed horse breeders and thought that this could happen in nature 3. Today horse breeders, dog breeders, and farmers do this to get the best animal or strongest crops D. Acquired traits 1. Jean-Baptiste Lamarck that that the traits that a parent acquired throughout their lives could be passed onto their children 2. This thought was wrong and we now know that if something is to be inherited it has to be passed through the parents DNA 3. Darwin noticed that an organisms traits could help them to survive E. Earth Changes Over Time 1. Rock layers indicate that there have been changes on the Earth over time 2. Charles Lyell hypothesized that small changes in rock have collected over hundreds of millions of years 3. Darwin used this to prove that the Earth was very old and that small changes over long periods of time add up F. Struggle to Survive 1. Thomas Malthus stated that all populations are affected by factors that limit growth • • • disease predation competition 2. Darwin used this thinking to reason that survivors have traits that have helped them to survive and these good traits will be passed onto their children G. Four parts to natural selection http://study.com/academy/lesson/how-darwins- observations-showed-the-process-of-natural-selection.html 1. Overproduction: when a plant or animals reproduces more offspring than the environment can support to ensure that some of their genes are passed to the next generation 2. Genetic variation: within a species there are natural variation that help certain organisms survive and reproduce • • • variation= differences in traits mutation=a change in genetic material that is an important source of variation the more variations in a population the more chances that there will be a trait that would be advantageous for the environment 3. Selection= traits that allow organisms to survive are “selected” for and will become more common in the next generations of offspring 4. Adaptation= an inherited trait that helps an organism survive and reproduce in its environment • • this is a favorable trait that an organism is born with- not one that that they acquire adaptations become more common in a population with each new generation https://youtu.be/5NdMnlt2keE 5. Genetic differences add up and even small differences can change a population over time • populations change with survivors reproducing & passing traits on 6. Extinction= occurs when all members of a species have died • greater competition, loss of habitat, & new predators are causes of extinction https://youtu.be/5NdMnlt2ke E Evolution of the Finch Beak https://youtu.be/mcM23M-CCog