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Evolution I Notes.pdf

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Biology (Biological Sciences)
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January 14, 2013 – Lecture # 4 Evolution I  dichotomy o split into two  dicho = in two  tomos = cut Darwin’s Bioraphy  Charles Darwin o 1827 – entered clerical studies at Cambridge  did well in Natural Theology - evidence of God in Nature o his ideas about gradualistic processes in geology influences his thoughts about biology  if landscaped like mountains formed from slow processes over hundreds of thousands of years – can the same be applied to changes in animals? o Visited isolated Galapagos Islands  Retrospectively (looking back on) it was very important  at the time, Darwin didn’t notice that finches on different islands were different, but related species  observations of superficially similar but unrelated species – vital to his research later o was chronically ill  others at the time noticed that there were fossils of organisms that do not resemble any living organisms at the time o thus the thought of extinction of species occurred o reasons for extinction differed: - natural disasters - supernatural disasters - not actually extinct, we just cant find these species o OR perhaps the apparent disappearance of species is actually one species changing slowly into another  Proposed by Lamarck - (note: extinction did occur, but Lamarck was philosophically opposed to it) o but scientists did not have plausible mechanisms for evolution  Lamarck was ridiculed for “inherited acquired characters” hypothesis  This fear of ridicule from the scientific community caused Darwin to now publish his theory of natural selection until he had enough evidence  In 1858, Alfred Russel Wallace independently arrived at the same theory as Darwin o Wallace mails his idea to Darwin and they present a joint paper on natural selection o Darwin, in fear that he would not be recognized for his work since he didn’t publish it yet, was spurred by Wallace to provide his careful analysis and present “On the Orgin of Species by Means of Natural Selection” in 1859  He was ridiculed by many for his ideas, but provided such sound logic that his arguments were virtually unshakeable Evolution by Natural Selection Darwin’s Arguments:  Observation 1: organisms produce many more offspring than survive to reproduce themselves (over-reproduction)  Observation 2: however, most populations are relatively stable in size  Observation 3: resources (eg. Food,land) are limited  Inference 1: organisms must compete for these limited resources and not all succeed o This inference inspired by Thomas Malthus, economist  Observation
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