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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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Presentation Transcript
slide1

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

slide2

similarity in form can reveal similarity in function

convergence – trait adapted to similar function but

with a different origin

slide3

similarity in form can reveal similarity in function

convergence – trait adapted to similar function but

with a different origin

slide4

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
slide5

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

slide6

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

slide7

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)

slide8

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

slide9

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

slide10

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”

slide11

Structural homology

Homology – similarities across species

especially when similar form is modified for different function

slide12

Developmental homology

Homology – similarities across species

especially when similar form is modified for different function

slide13

Biochemical homology

Homology – similarities across species

especially when similar form is modified for different function

also commonality of genetic code, amino acids

slide14

Related species & biogeography

Adaptive radiation of honeycreepers on Hawaiian islands

slide16

Selective breeding & direct observation

experimental evolution; rapid evolution in nature

Teosinte

slide17

Selective breeding & direct observation

experimental evolution; rapid evolution in nature