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Occurrence of evolution was debated - PowerPoint PPT Presentation


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Occurrence of evolution was debated. Georges Cuvier (early 1800’s) – paleontologist & comparative anatomist - established extinction as fact: described large mammal fossils with no living members of the species recent fossils resembled extant species more than ancient fossils do

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Occurrence of evolution was debated


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    1. Occurrence of evolution was debated • Georges Cuvier (early 1800’s) – paleontologist & comparative anatomist • - established extinction as fact: • described large • mammal fossils • with no living members • of the species • recent fossils resembled extant species more than ancient fossils do • suggested that extinctions were caused by periodic global catastrophes • - did not think evolution could occur: • believed that function dictates form, and similarity in form • reveals similarity in function, not common ancestry “Irish elk” mastodon

    2. similarity in form can reveal similarity in function convergence – trait adapted to similar function but with a different origin

    3. similarity in form can reveal similarity in function convergence – trait adapted to similar function but with a different origin

    4. Occurrence of evolution was debated • Étienne Geoffroy-St. Hilaire (early 1800’s) – vertebrate morphologist • believed that form dictates function: similarity due to shared “archetype” • evidence:homologous structures, • vestigial traits • evidence:embryonic changes • thought that form could be changed • by the environment and inherited • thought that morphological change • did not have to be gradual

    5. three-toed sloth giant ground sloth Charles Darwin ends the debate Charles Darwin - medical school dropout; earned a theology degree - botany professor nominated him to be a naturalist on a voyage to South American (1831-1836), HMS Beagle encountered more evidence for evolution: biogeography - fossils similar to extant species in South American, but not elsewhere

    6. Charles Darwin ends the debate Charles Darwin - medical school dropout; earned a theology degree - botany professor nominated him to be a naturalist on a voyage to South American (1831-1836), HMS Beagle encountered more evidence for evolution: biogeography - new species in Galápagos that were similar to mainland species - differences in species among islands on the Galápagos

    7. Charles Darwin ends the debate Charles Darwin - medical school dropout; earned a theology degree - botany professor nominated him to be a naturalist on a voyage to South American (1831-1836), HMS Beagle encountered more evidence for evolution: biogeography - 14 species of finches, adapted to different niches (different food sources)

    8. Charles Darwin ends the debate Charles Darwin - medical school dropout; earned a theology degree - botany professor nominated him to be a naturalist on a voyage to South American (1831-1836), HMS Beagle encountered more evidence for evolution: biogeography - Australian marsupials outwardly similar and with similar niches to placental species elsewhere Australian sugar glider North American flying squirrel

    9. Charles Darwin ends the debate Charles Darwin - medical school dropout; earned a theology degree - botany professor nominated him to be a naturalist on a voyage to South American (1831-1836), HMS Beagle encountered more evidence for evolution: biogeography - fossils similar to extant species in South American, but not elsewhere - new species in Galápagos that were similar to mainland species - differences in species among islands on the Galápagos - 14 species of finches, adapted to different niches (food source) - Australian marsupials outwardly similar and with similar niches to placental species elsewhere

    10. common ancestry - homology - related species - biogeography change over time - vestigial traits - selective breeding - direct observation - fossil record History of “evolutionary thought” & evidence for evolution Charles Darwin - not the first to suggest that evolution has occurred - amassed the evidence for “descent with modification” - suggested natural selection as a mechanism Evidence for “descent with modification”

    11. Structural homology Homology – similarities across species especially when similar form is modified for different function

    12. Developmental homology Homology – similarities across species especially when similar form is modified for different function

    13. Biochemical homology Homology – similarities across species especially when similar form is modified for different function also commonality of genetic code, amino acids

    14. Related species & biogeography Adaptive radiation of honeycreepers on Hawaiian islands

    15. Vestigial traits – no longer in use, but present in reduced form

    16. Selective breeding & direct observation experimental evolution; rapid evolution in nature Teosinte

    17. Selective breeding & direct observation experimental evolution; rapid evolution in nature