lecture 13 - BIO10 student - evolution II

lecture 13 - BIO10 student - evolution II - Lecture 13 how...

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Lecture 13: how populations evolve (Ch 13) how biological diversity evolves (Ch 14)
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Plan for today A. How does evolution happen? 1. Natural selection 2. Sexual selection 3. Genetic drift 4. Gene flow B. How do we get new species?
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This cladogram represents an imaginary group of organisms A, B, C, D, and E. Which position number identifies the common ancestor for species C and E? a. 1 b. 2 c. 3 d. 4 Clicker Question
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This cladogram represents an imaginary group of organisms A, B, C, D, and E. Which two living species are the most closely related? a. A and B b. B and C c. C and D d. A and D Clicker Question
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Evolution occurs because of natural selection, sexual selection, genetic drift and gene flow, which all require genetic diversity. What is the driving force for genetic diversity? a. asexual reproduction b. g ood ‘ ol hydrogen bonding c. mutation d. multigene Inheritance Clicker Question
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Natural selection works with genetic variation. The ultimate source of genetic variation is mutation in the DNA. In sexually reproducing organisms with long generation time, what process(es) account(s) for individual variation? a. random fertilization b. crossing over c. independent assortment d. all of the above Clicker Question
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Natural Selection
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Darwin’s observations: - Geographic proximity is a better predictor of relationship between organisms than similarity in environment - Fossils found in South America were distinctly South American - Remote Galápagos islands contained species found nowhere else in the world but resembled South American species
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- Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859 - Main concepts: 1) Organisms inhabiting Earth today descended from ancestral species 2) Change occurs as a result of “descent with modification”, with natural selection as the mechanism 3) Natural selection leads to the “fittest” surviving (measured by # of offspring)
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Darwin based his theory of natural selection on two key observations
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Natural Selection - Defined: individuals with certain inherited traits are more likely to survive and reproduce than are individuals with other traits - Natural selections leads to populations changing over generations….evolutionary adaptation
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A Trinidad tree mantid that mimics dead leaves
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A leaf mantid in Costa Rica
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A flower mantid in Malaysia
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What makes a trait an adaptation?
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