Download Evidence supporting evolution

Evidence for Evolution
Learning Targets
 Explain the evidence for evolution with regards to
the fossil record, geographic distribution of
organisms, anatomical structures, embryology, and
molecular biology.
 Be able to compare and contrast homologous,
analogous, and vestigial structures.
Review of Natural Selection
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Remember Darwin came up with the Theory of Evolution.
Natural selection leads to Descent with Modification –
traits are passed down from generation to generation and
sometimes undergo changes or modifications over time
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Evidence for Evolution
 Fossil record
Shows change over time.
 Fossils of extinct species provide evidence of
shared ancestry and how organisms and the
environment have changed over time.
 Biogeography
 Differences and similarities between
organisms in different locations around the
world.
 Provides evidence of how modern species
share a common ancestor but have evolved to
fit environments in different locations.
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Evidence for Evolution
 Anatomical structures
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comparing body structures, similarities and differences.
 Molecular record
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comparing protein & DNA sequences.
The greater the similarities in DNA and protein sequences, the
more likely two organisms share a common ancestor.
Universal genetic code (ATGC) provides evidence that ALL life
forms are related.
Evidence for Evolution
 Embryology
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comparison of stages of embryonic development between
organisms of different species.
Embryos of closely related species have similar stages of
development.
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Anatomical Structures
 Homologous structures-structures that come from
the same origin, but have different functions.
homo- = same
 -logous = information
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 Forelimbs of human, cats, whales, & bats
 same structure
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same development in embryo
different functions
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on the inside
on the outside
evidence of common ancestor
Divergent Evolution (similar ancestor, but due to isolated
environments evolve to adapt best to environment)
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Anatomical Structures
 Analogous structures:  structures
that have a similar function but do NOT
have similar internal structure.
 look similar
 on the outside
 same function
 different structure & development
 on the inside
 different origin
 no evolutionary relationship
 Convergent Evolution (similar
living environments, adapted in
similar way).
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Convergent evolution (Analogous structures)
evolving similar solutions to similar problems
 3 groups with wings
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Does this mean they have a
recent common ancestor?
Analogous or Homologous?
 Dolphins: aquatic mammal
 Fish: aquatic vertebrate
both adapted to
life in the sea
 not closely related
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Anatomical Structures
 Vestigial Structures: Remnants of structures that
may have had important functions in an ancestral
species but have no clear function in the modern
species  shows common ancestry with adaptations
to changing environments.
Discuss with a Partner
WHAT ARE THE MAIN EVIDENCES
FOR EVOLUTION?
WHICH DO YOU FEEL IS THE
STRONGEST SUPPORT OF NATURAL
SELECTION?
WHY?