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Download Natural Selection and the Origin of new species
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• Parents pass on traits that they get during their lives . Giraffes stretching to reach food Carrying capacity rare several million years 4.5 billion years • Humans make gradual changes to species to get organisms we want through encouraging breeding of those with desired traits selective breeding have traits designed to attract a mate https://www.youtube.com/watch?v=CYcs73oeFkc Darwin • HMS Beagle Galapagos • Different finches. explanation for natural phenomena If an organism is better able to survive where it lives, it survives. lity to survive and reproduce in a given environment differences within a species are variations that allow an organism to better survive in their environment • Adaptations are central to Natural Selection • Variations that are beneficial are selected for • Camouflage-blending in with surroundings to keep from being spotted • Mimicry-looking like something dangerous, which makes predators afraid • Gives them an advantage over other members of their species • They are more likely to survive and pass the trait on Which of the organisms to the left can sting you? None of them! All are flies, and are 100% harmless. None even have stingers! extreme phenotype Both extreme phenotypes Selection-Intermediate phenotype • Extremely misunderstood topic • Change in the frequency of alleles in a population over time. • Over time, certain traits become more common in a population • The variations are often the result of a beneficial mutation giving the organism something it did not previously have • Ex. Antibiotic resistance in bacteria 2 species when part of the population becomes isolated https://www.youtube.com/watch?v=YCoEiLOV8jc • Darwin’s way of describing evolution. • The similar species (ex. The different species of Finch on the Galapagos Islands) all had a common ancestor • A mother population of finches that changed over time into all of the different species that we see now. • Often caused by changing environmental conditions • For the finches, it was availability of food • Finches from the initial population that had slightly larger beaks did better than those with smaller beaks when large nuts and seeds were the primary food source available • This led Darwin to conclude that, over millions of years, all organisms descended from a single common ancestor • The “Tree of Life” • Convergent • Divergent • Coevolution • Many species evolving from a single ancestral species extinction • Extinction is the death of the last member of a species Fossils Biogeography Embryology-study of development At one point, you had gills and a tail! • Homologous structures-similar Vestigial Structures https://www.youtube.com/watch?v=OAfw3akpRe8 • All organisms, past and present, share DNA • • • • All humans are 99.9% similar Humans and chimpanzees share 98% of DNA Humans and grass have 15% similar DNA Humans and bacteria have 7% similar DNA • Follows “tree of life” pattern • Organisms more closely related have more DNA in common
