Biology 145 EVOLUTION - Claremont...
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9/19/2013 1 EVOLUTION Biology 145 Lecture 2 – 19 th century progress Evidence for Evolution prior to 1830
Transcript of Biology 145 EVOLUTION - Claremont...
9/19/2013
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EVOLUTIONBiology 145
Lecture 2 – 19th century progress
Evidence for Evolution prior to 1830
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Evidence for Evolution prior to 1830
More than 700,000 species of beetle alone. WHY???
“The Creator, if He exists, has an inordinate fondness for beetles“ – JBS Haldane
Evidence for Evolution prior to 1830
Not all individuals within a species are identical ‐VARIATION!!
Cepaea nemoralis
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Evidence for Evolution prior to 1830
Comparative anatomy
Pentadactyl limbs
HOMOLOGOUSstructures – shared form due to common ancestry
Evidence for Evolution prior to 1830
Vestigal Structures
(Proteus anguinus)
Astyanax mexicanus
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Evidence for Evolution prior to 1830
Embryology
(Darwin; The Descent of Man, 1871)
Evidence for Evolution prior to 1830
Invariate sequence of the fossil record
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Evidence for Evolution prior to 1830
Animal and Plant breeding
~ 12,000 years
A mechanism for Evolution:
Jean Baptiste LAMARK (1744 – 1829)
Recherches sur l'organisation des corps vivants, 1802.
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”
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A mechanism for Evolution:
LAMARKISM
Strong rational basis
Explained the fossil record, including extinction
Seemed to fit breeding experiments
BUT….
Accounts for evolution within a lineage, but not speciation
Not supported by 20th Century genetics
TIME
Change
Anagenesis versusCladogenesis
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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 1809 – 19April 1882
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Voyage of the Beagle
Dec 27 1831 –Oct 2 1836
“On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.”
November 24th, 1859
23 years after return of the Beagle
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Alfred Russel Wallace
Amazon – 1848 ‐ 1852
‘Malay Archipelago’ – 1854 ‐ 1862
“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” ‐ 1858
18th June?, or…. 1st July 1858 ???
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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
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The Darwin – Wallace Theory of Natural Selection
1. All organisms show variation2. 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 variation2. At least some variation is heritable3. All organisms produce more offspring than can
survive
4. There is competition between offspring for survival
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The Darwin – Wallace Theory of Natural Selection
1. All organisms show variation2. At least some variation is heritable3. All organisms produce more offspring than can
survive4. 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 variation2. At least some variation is heritable3. All organisms produce more offspring than
can survive4. There is competition between offspring for
survival5. 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
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The Modern SynthesisGenetics – rediscovery of Mendel’s work
R. A. FisherJBS HaldaneSewall Wright
George Gaylord Simpson – PaleontologyErnst 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 pre‐determined. Gradualism does not mean constant rate of change.
