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Evidence of Evolution by Natural Selection - PowerPoint PPT Presentation


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Evidence of Evolution by Natural Selection. Dodo bird. Evidence supporting evolution. Fossil record transition species Anatomical record homologous & vestigial structures embryology & development Molecular record protein & DNA sequence Artificial selection human-caused evolution.

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evidence supporting evolution
Evidence supporting evolution
  • Fossil record
    • transition species
  • Anatomical record
    • homologous & vestigial structures
    • embryology & development
  • Molecular record
    • protein & DNA sequence
  • Artificial selection
    • human-caused evolution
fossil record
Fossil record
  • Layers of sedimentary rock contain fossils
    • new layers cover older ones, creating a record over time
    • fossils within layers show that a succession of organisms have populated Earth throughout a long period of time
anatomical record
Anatomical record
  • Homologous structures
    • similarities in characteristics resulting from common ancestry
homologous structures
Homologous structures
  • Similar structure
  • Similar development
  • Different functions
  • Evidence of close evolutionary relationship
    • recent common ancestor
analogous structures
Analogous structures
  • Separate evolution of structures
    • similar functions
    • similar external form
    • different internal structure & development
    • different origin
    • no evolutionary relationship

Don’t be fooledby their looks!

Solving a similar problem with a similar solution

convergent evolution
Convergent evolution
  • Flight evolved in 3 separate animal groups
    • evolved similar “solution” to similar “problems”
    • analogous structures

Does this mean they have a recent common ancestor?

parallel evolution
Parallel Evolution
  • Convergent evolution in common niches
    • filling similar ecological roles in similar environments, so similar adaptations were selected
    • but are not closely related

marsupial

mammals

placental

mammals

vestigial organs
Vestigial organs
  • Modern animals may have structures that serve little or no function
    • remnants of structures that were functional in ancestral species
      • snakes & whales — remains of pelvis & leg bones of walking ancestors
      • eyes on blind cave fish
      • human tail bone

This is notLaMarck’s loss from “disuse”!

comparative embryology
Comparative embryology
  • Similar embryological development in closely related species
    • all vertebrate embryos have similar structures at different stages of development
      • gill pouch in fish, frog, snake, birds, human, etc.
molecular record

Human/kangaroo

100

Human/

cow

Dog/

cow

75

Rabbit/

rodent

Human/rodent

Llama/

cow

Horse/

donkey

50

Nucleotide substitutions

Horse/cow

Sheep/

goat

Pig/

cow

25

Goat/cow

0

0

25

50

75

100

125

Millions of years ago

Molecular record
  • Comparing DNA & protein structure
    • universal genetic code!
      • DNA & RNA
    • compare common genes
      • cytochrome C (respiration)
      • hemoglobin (gas exchange)

Why comparethese genes?

Closely related species have sequences that are more similar than distantly related species

  • DNA & proteins are a molecular record of evolutionary relationships
building family trees
Building “family” trees

Closely related species (branches) share same line of descent until their divergence from a common ancestor

slide13

Don’t be a Dodo…

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