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Evolut-Sumry - Biology 200 Evolution Summary Notes A B C...

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Biology 200 Evolution - Summary Notes A. Jean Lamarck (1809) 1. Evolution by use and disuse and the inheritance of acquired traits B. Charles Darwin (1858) 1. Evolution by natural selection C. The Facts of Charles Darwin’s Theory 1. Overproduction - Limited resources 2. Inheritable variation 3. Natural selection (differential reproduction) 4. Changes in population gene pools D. Modern Synthesis (NeoDarwinism) 1. The modern understanding of evolution, incorporating Darwinian evolution and modern genetics (which is able to explain the source of variation and the intricate ways gene pools can change. E. Population Genetics 1. Study of the patterns of variation in population gene pools and how these patterns vary spatially and temporally. 2. Hardy-Weinberg Theorem - a gene pool will remain the same if: the population is large, matings are random, no mutations occur, no gene flow occurs, and no natural selection occurs (these terms are defined below). F. Factors Which Can Change Gene Pools 1. Genetic Drift : a change in a gene pool due to chance; Limited to small populations a. Bottleneck effect - population is reduced in size (e.g. by a natural disaster). b. Founder Effect - when a small subgroup of a population colonizes a new habitat. 2. Gene Flow : a change in a gene pool due to immigration or emigration 3. Mutation : a change in a gene pool due to inheritable changes in genes or chromosomes; mutations can be beneficial, harmful or neutral depending on their success in the presence of current environmental conditions. 4. Nonrandom mating : a change in a gene pool due to mating preference (e.g. female peacocks prefer males with the longest tail feathers) 5. Natural selection : a change in a gene pool due to differential reproduction (i.e. when some individuals have a reproductive advantage based on inheritable characteristics) 1
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G. Biological fitness - is a measure of an individuals reproductive success 1. Biological phenomena have a history, and this history (and the phenomena) is best understood through biological fitness. a. Example: Why do female black widows eat their male mates? b. Example: Why do human females enter menopause near the age of 50 rather than at 40 years or 60 years? c. Example: Why do most human babies weigh close to 7 pounds at birth? d. Example: Why (how) do some insects resemble bird poop? Types of Natural Selection 1. Stabilizing Selection: selection for an intermediate phenotype (e.g. birth weights in humans) 2. Directional Selection: selection for an extreme phenotype (e.g. antibiotic resistance in bacteria) 3. Diversifying (Disruptional) Selection: selection for extreme phenotypes over intermediate phenotypes (e.g. selection for the sickle cell allele in humans living in different regions with and without the presence of malaria) Sexual Selection : selection for a trait that is related to mate selection (e.g. bird plumage, lion mane, antlers, ...) . Is there any evidence of sexual selection in humans?
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