Ch 18.pdf - BIOLOGY Chapter 18 EVOLUTION AND THE ORIGIN OF...

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9/12/2017 1 BIOLOGY Chapter 18 EVOLUTION AND THE ORIGIN OF SPECIES PowerPoint Image Slideshow 18.1 | UNDERSTANDING EVOLUTION By the end of this section, you will be able to: Describe how the present-day theory of evolution was developed Define adaptation Explain convergent and divergent evolution Describe homologous and vestigial structures Discuss misconceptions about the theory of evolution DEVELOPING THE THEORY OF EVOLUTION Species are static and unchanging – Plato’s writings (~400 BCE) Species ____________over time …a concept well before Darwin Georges-Louis Leclerc Comte de Buffon (naturalist, 1700’s) Different regions have different species, there are extinct species ______________________– (Scottish naturalist same time) Geological change is ___________________________ _______________________________________________ NOT the CURRENT THOUGHT that history of earth is SHORT with geology determined by catastrophic events ______________________– (geologist) Popularized Hutton’s ideas; friend of Darwin, influenced him Jean-Baptiste ___________________– 1800’s Evolution of organisms – published in a book Inhertance of ________________________________ MID 1800’S: 2 MEN, 1 MECHANISM OF EVOLUTION Alfred Russel _____________ Brazil, Amazon (1848-1852) ; Malay Archipelago (1854-1862; green) Similar yet different organisms on islands that are geographically close to each other Charles __________________ South America, Australia, Africa, Galapagos on H.M.S. Beagle (1831-1836) SEES the same patterns. FIGURE 18.2 Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources. Ancestral species change over time, modified. Both Wallace and Darwin dteremine that species change over time and the MECHANISM behind this is ________________________________ NATURAL SELECTION Also Called, “survival of the ______________” 3 principles of nature: Most traits are ______________ _________ offspring are born than can ______, so competition exists for resources Thomas __________ – economist essays about humans (1766-1834 England) Offspring inherited traits_______among siblings Natural selection = “descent with modification” Over time: changes in populations of organisms (overall ___________) that make it more adapted
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9/12/2017 2 FIGURE 18.3 Both (a) Charles Darwin and (b) Alfred Wallace wrote scientific papers on natural selection that were presented together before the Linnean Society in 1858. One year later Darwin finished his famous book outlining detailed explanation of natural selection and how it is the driver behind evolution of species. What was it called? NATURAL VARIATION: SELECTED UPON Natural Selection can only select for an EXISTING natural variety (genetically based) in a population Gene pool – all of the variations (alleles) of genes present within a population of a species Genetic diversity leads to ___________ diversity How would you get new genetic variations?
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