Epistemology and Evolution. History of Evolutionary Thought. Rise and Fall: in a nutshell. Age of the Earth. Charles Lyell ( ) 9/27/2012

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1 History of Evolutionary Thought Epistemology and Evolution Argument from Authority Reality can be explained by scripture or by persons Methodological Naturalism Nature to explain nature Supernatural explanations are not allowed Rise and Fall: in a nutshell Greeks used methodological naturalism After, Aristotle and scripture used for knowledge Methodological naturalism rejected not entirely 18 th century: Age of Enlightenment Search for laws Aristotle ( B.C.E.) Plato s student Studied ecology, biology, and geology Continued Plato s idea of eidos Concept of eidos for species persisted until Darwin Age of the Earth Greeks: eternal Bible scholars: ~ 5000 years George Buffon ( ), French naturalist 75K to 2-3M years Used observations James Hutton ( ), Scottish geologist Founder of modern geology Earth is incredibly old Uniformitarianism Charles Lyell ( ) Principles of Geology (1830) Based on uniformitarianism Was the geology textbook of Darwin s day Friend of Darwin 1

2 Natural History and Classification Aristotle proposed a simple classification with genus and species Scala naturae: Great Chain of Being Karl von Linne (Carl Linnaeus, ) Binomial nomenclature Systema naturae Was all about sex! Organisms and their environment William Paley ( ) Natural Theology God as Watchmaker Extinctions are impossible Lewis and Clark Georges Cuvier ( ), French Father of paleontology Extinctions are real Change through time Greeks proposed it Bible scholars forbid it Organisms created perfectly Immutability of species Erasmus Darwin ( ) Charles Darwin s grandfather Zoonomia (poem) Organisms evolve in scala naturae Publically ridiculed Change through time Robert Chambers Vestiges of the Natural History of Creation (1845) Organisms evolve Process is slow Emphasis on populations Jean-Bapiste Lamarck ( ) Zoological Philosophy (1809) Inheritance of acquired characteristics Change through time Along came Darwin Grandfather and father were doctors Went to Edinburgh for two semesters to study medicine dropped out Went to Christ s College to be a clergyman Studied natural theology: geology and natural history Energetic field student Urged to go aboard the HMS Beagle The captain (Robert FitzRoy) needed a companion of similar social stature 2

3 Voyage of the HMS Beagle Surveying trip Map coastlines Test new equipment Naturalist on board was the doctor Was supposed to be three year journey went 5 Left 1831, Darwin age 22 Went to Azores, S. America, Galapagos, Australia, Tahiti Voyage of the Beagle Voyage of the HMS Beagle Darwin collected fossils and living organisms Ship s official naturalist left Darwin shipped materials back Became famous as a naturalist Wrote several books soon after Voyage of the HMS Beagle Observations Each Galapagos island had its own turtle, mockingbird Fossil species similar but not the same as extant species Similar species over land masses Struggle for existence Thomas Malthus Darwin, from boat to book After the Beagle trip, married and settled in the country Studied barnacles, worms, seeds Researched like mad Did not work for a living Married cousin, invested, inheritance Thought about natural selection and evolution Thousands of letters of correspondance Alfred Russel Wallace ( ) Studied butterflies in southeast Asia Knew many of the same facts as Darwin Sent Darwin an outline of natural selection in 1855 In 1858, co-authored a paper with Darwin on natural selection Not a big hit 3

4 Origin of Origin Natural selection sensu Darwin Inspired by Wallace, finally published his draft On the Origin of by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life in 1859 Stressed the importance of variation within a species Natural selection Common ancestry: hierarchical branching Taxonomy reflects ancestry Happens when More organisms are born than can survive and reproduce Competition to represent the next generation Those organisms more likely to survive because of some trait will leave more offspring If that trait is heritable then the offspring will have that trait If conditions continue then that trait will spread in the population Process related to artificial selection Major Darwinian Ideas Natural selection Common ancestry Interspecific variation Organisms vary within a species There are fitness consequences to this variation Male tail streamers length as a predictor of reproductive success: (a) First brood breeding success, (b) Annual breeding success, (c) Successful genetic offspring in first brood, and (d) Annual genetic breeding success. Vortman Y et al. Behavioral Ecology 2011;beheco.arr139 The Author Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved. For permissions, please journals.permissions@oup.com 4

5 The variation is heritable Natural selection occurs Dave Reznick Caribbean Anoles Phylogenetic trees Common Ancestry Pre-Darwinian Linnean classification Post-Darwinian Classification A D E A B D E F Genus C B Genus G F Common Ancestor C Common Ancestor G Family H Common Ancestor H 5

6 Phylogenetics and Taxonomy Pre-Darwinian Taxonomy Classification arbitrary Post-Darwinian Taxonomy Classification represents lineages Taxon = monophyletic group Taxonomy should reflect phylogeny Reception of Origin Most scientist accepted evolution Natural selection not as widely accepted Issues with Darwin Eusocial insects Mechanism of heredity unknown Time To recap Darwin s contributions Evidence that evolution happened Mechanism of evolution: natural selection Pattern of evolution: heirarchical Rise of the Geneticists Weisman's germplasm hypotheses Contra Lamarck Hugo DeVries worked with mutations genes Early Geneticists Variation was discrete Mutations produced large changes Naturalists Most variation was continuous 6

7 Population Genetics Resolved the dispute between naturalists and geneticists Modern Synthesis of 1940 s Ronald Fisher Theodosius Dobzhansky Sewall Wright JBS Haldane Ernst Mayr George Simpson Population Genetics Evolution is Descent with modification Change in gene frequency 7