5_Evolution_ENV1020

5_Evolution_ENV1020 - In considering the origin of species,...

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“In considering the origin of species, it is quite conceivable that a naturalist . . . might come to the conclusion that species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species, inhabiting this world, have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration.” -Darwin, The Origin of Species
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Adaptation Adaptation and Evolution and Evolution Chapter 5
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Over 2 million (identified) species on Earth WHERE DO THEY ALL COME FROM?
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Charles Robert Darwin (February 12, 1809- April 19, 1882) In 1835, Darwin embarked on a 5-year world trip on the HMS Beagle . Along the way, he visited the Galapagos Islands and became convinced that various populations evolved from their ancestral forms.
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Darwin’s voyage aboard the HMS Beagle The Galapagos Volcanic Islands
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Darwin’s Galapagos Finches 14 closely related species on Galapagos Isles: - Geospiza spp., Camarynchus spp., Certhidea sp., Pinaroloxias sp. Differences in beak shape and size - Each beak adapted for a specialized feeding task - Each species found on a different environment
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The Origin of Species by Natural Selection (1859) In 1838, After reading an essay by Thomas Malthus, Darwin theorized that some individuals would have a competitive advantage conferred by favorable characteristics. - After 22 years of reflecting & self-debating, correspondence with Alfred Rusell Wallace convinced Darwin to make his theory public in 1859.
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Phenotype = observable traits or characteristics of an organism e.g., appearance, physiological function, behavior The phenotype is what we see when we examine an organism (e.g., tall or short, blonde or brunette, normal hemoglobin or sickle-cell hemoglobin, etc. ..) . The phenotype represents the interaction of two sources of influences: Genotype (gene or genes that encode for that trait) Environment Populations generally exhibit phenotypic variation in most traits.
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Population = all individuals of the same species that live in a given area at the same time Two distinguishing attributes: members of the pop. are reproductively compatible with one another (i.e., high probability of mating with one another relative to probability of mating with members of some other pop.). members of the pop. are similar to one another but different from members of other populations Upon close inspection, we usually find evidence of variation AMONG the individuals comprising the population i.e., some variation in appearance, physiology or behavior We refer to this as phenotypic variation  
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01/31/11
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01/31/11
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Persistent changes in gene frequencies within a population (or species) over generations. Genes are transmitted from
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This note was uploaded on 08/26/2011 for the course ENV 102 taught by Professor Steve during the Spring '11 term at CUNY Hunter.

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5_Evolution_ENV1020 - In considering the origin of species,...

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