EvolutionLect

EvolutionLect - Biological Diversity and Evolution A....

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Biological Diversity and Evolution A. P RE -D ARWINIAN E XPLANATIONS FOR D IVERSITY Plato: Typological thinking and essentialism (see Mayr) The domain of pure ideas (in the heavens) has more reality and is more perfect than the material world Each species represents a "pure" idea from God's mind Species are unchanging and constant because the "ideas" that created them are eternal (i.e., typological thinking , or essentialism ). From Creationism to Evolution: A RISTOTLE S Scala naturae : The great chain of being, from least to most perfect. C REATIONISM : Species are unchanging; special creations from design (from Plato and early Christianity). C ATASTROPHISM : Relaxation of creationist dogma to account for extinctions seen in fossil record––> multiple acts of creation. I DEALISTIC M ORPHOLOGY : Variations around "pure" forms as adaptations to local environmental demands––> introduced the notion of adaptive variations . J.-B. L AMARK (1809): Species change as they strive to achieve greater perfection ––> evolution proposed Mechanism: Inheritance of acquired characters .
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B. C HARLES D ARWIN (1859): A M ECHANISM FOR E VOLUTION Evolution as fact (see Mayr's five sources of evidence): Evidence from animal breeders (selection of favorable traits) The fossil record: from simple to more complex forms forms found in adjacent strata are more similar than forms found in more distant strata fossils on a given continent resemble living species on that continent Biogeography (distribution of species on land masses): Insular species resemble those found on mainland similar climatic zones contain different species Morphology: number of homologous characters common among species is a function of how closely related they are by virtue of common descent
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EvolutionLect - Biological Diversity and Evolution A....

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