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Transcript
More embryo examples Darwin Goes Sailing And finds finches! More finches Natural Selection In 4 easy steps! 1.Overproduction 2. Genetic variation 3. Struggle to survive 4.Successful reproduction 1. Overproduction Why is over-production important? For example, a rabbit can have a litter of 4 babies every month. In one year, a rabbit can produce 48 babies! If they all have babies the next year, how many babies would that be? 2. Genetic Variation We’re all unique! 3. Struggle to Survive Organisms must • Escape predators • Find food • Conserve energy • Find mates 4. Successful Reproduction Why is this important? How does evolution happen? One way is by “genetic drift” Examples: Horse Peppered moth How does evolution happen? An important factor is ISOLATION. The same species, in different environments, can evolve differently. This is how one common ancestor can evolve into several different species. Divergent evolution Founder effect If only a small population is available to breed, the distribution of traits changes. Mutations Can be deadly, either prior to birth (miscarriage), or shortly after. Lethal white syndrome Rye nose Mutations Can be neutral: CGU CGC CGA CGG AGA AGG All code for Arginine. What if you suffered a mutation that effected the development of your gill slits? Mutations Can be harmful but not deadly: Down’s syndrome Marfan’s syndrom Dwarfism Polydactyly Mutations Can be good! Bohlinia Samotherium Giraffe! Sickle cell anemia??? Giraffe Laws In Atlanta, Georgia, it is illegal to tie a giraffe to a telephone pole or street lamp. In Idaho Residents may not fish from a giraffe's back. No, this has nothing to do with science. Lack of Evolution The Hardy-Weinberg Principle: Will occur if the population is • infinitely large • isolated from other populations • mating is random • all genotypes are equally viable Lack of Evolution 1. Extinction 2. • • • Lack of need to change: Sharks Horseshoe crabs Cockroach More about Natural Selection http://evolution.berkeley.edu/evolibrary/articl e/sneakermales_01
