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Genetics and Evolution

Genetics and Evolution. Think about it…. Why do we observe certain traits more often than others?. …Because of N atural Selection The process whereby organisms better adapted to their environment tend to survive and produce more offspring . (theory proposed by Charles Darwin )

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Genetics and Evolution

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  1. Genetics and Evolution

  2. Think about it…

  3. Why do we observe certain traits more often than others? • …Because of Natural Selection • The process whereby organisms better adapted to their environment tend to survive and produce more offspring. (theory proposed by Charles Darwin) • Genetic Drift: chance events cause allele frequencies to change over time (see this more in small populations) Example: Green beetles and brown beetles in a small population, Majority of the green beetles are squished due to random chance Results in a greater allele frequency for brown beetles

  4. Genetic Drift

  5. Bottleneck Effect – limits the frequency of alleles in population

  6. How has Natural Selection led to the organisms we see on earth today? Common Ancestor Common Ancestor

  7. The diagram on the other page… • Is known as a PHYLOGENETIC TREE • A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species based upon similarities and differences in their physical and/or genetic characteristics • Aids in classifying organisms and showing the evolutionary lineages of organisms

  8. Phylogenetic trees also assist in naming organisms… • Scientific naming= giving all organisms on earth a title of Genus and Species • Example: Homo sapiens • Notice: • the entire name is italicized • “Homo”= Genus and is always first and CAPITALIZED • “sapiens”= species and is always second and in lower case

  9. Genus and Species also assist with determining relatedness • Remember Pisum sativum? • Genus and species of Gregor Mendel's pea plants.

  10. Which organism is most closely related to Pisum sativum? Explain… • A.) Lepidium sativum • B.) Coriandrum sativum • C.)Pisum fulvum Answer= Pisumfulvum (tawny pea) Same Genus but different species= most closely related organisms

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