9/19/2013. Lecture 2 19 th century progress. Biology 145 EVOLUTION. Evidence for Evolution prior to 1830

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1 Lecture 2 19 th century progress Biology 145 EVOLUTION 1

2 More than 700,000 species of beetle alone. WHY??? The Creator, if He exists, has an inordinate fondness for beetles JBS Haldane Not all individuals within a species are identical VARIATION!! Cepaea nemoralis 2

3 Comparative anatomy HOMOLOGOUS structures shared form due to common ancestry Pentadactyl limbs Vestigal Structures Astyanax mexicanus (Proteus anguinus) 3

4 Embryology (Darwin; The Descent of Man, 1871) Invariate sequence of the fossil record 4

5 Animal and Plant breeding ~ 12,000 years A mechanism for Evolution: Jean Baptiste LAMARK ( ) Recherches sur l'organisation des corps vivants, Lamarck s Postulates: Organisms have the ability to adapt to their environments over the course of their lifetimes Organisms can pass these acquired characteristics to their offspring Organisms have an innate drive to perfection 5

6 A mechanism for Evolution: LAMARKISM Strong rational basis Explained the fossil record, including extinction Seemed to fit breeding experiments BUT. Not supported by 20 th Century genetics Accounts for evolution within a lineage, but not speciation Anagenesis versus Cladogenesis Change TIME 6

7 James Hutton Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe 1788 "all inferences from experience suppose... that the future will resemble the past" UNIFORMITARIANISM!!! Charles Darwin 12 February April

8 Voyage of the Beagle Dec Oct On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. November 24 th, years after return of the Beagle 8

9 Alfred Russel Wallace Amazon Malay Archipelago On the Law which has regulated the Introduction of New Species 1855 "Every species has come into existence coincident both in space and time with a closely allied species" On the tendency of varieties to depart indefinitely from the original Type th June?, or. 1 st July 1858??? 9

10 The Darwin Wallace Theory of Natural Selection 1. All organisms show variation The Darwin Wallace Theory of Natural Selection 1. All organisms show variation 2. At least some variation is heritable 10

11 The Darwin Wallace Theory of Natural Selection 1. All organisms show variation 2. At least some variation is heritable 3. All organisms produce more offspring than can survive The Darwin Wallace Theory of Natural Selection 1. All organisms show variation 2. At least some variation is heritable 3. All organisms produce more offspring than can survive 4. There is competition between offspring for survival 11

12 The Darwin Wallace Theory of Natural Selection 1. All organisms show variation 2. At least some variation is heritable 3. All organisms produce more offspring than can survive 4. There is competition between offspring for survival 5. Offspring with variations that are advantageous will have a better chance of survival and reproduction The Darwin Wallace Theory of Natural Selection 1. All organisms show variation 2. At least some variation is heritable 3. All organisms produce more offspring than can survive 4. There is competition between offspring for survival 5. Offspring with variations that are advantageous will have a better chance of survival and reproduction 6. The advantageous variations will be more common in the next generation 12

13 The Modern Synthesis Genetics rediscovery of Mendel s work R. A. Fisher JBS Haldane Sewall Wright George Gaylord Simpson Paleontology Ernst Mayr Speciation All evolutionary phenomena can be explained in a way consistent with known genetic mechanisms and the observational evidence of naturalists. Natural Selection is by far the main mechanism of change; In palaeontology, extrapolation from microevolution to macroevolution explains observations. Historical contingency means the course of evolution is not predetermined. Gradualism does not mean constant rate of change. 13