Transcript Evidence for Evolution

Evidence for Evolution
Chapter 22
What you need to know!
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Several examples of evidence for
evolution.
The difference between structures
that are homologous and those that
are analogous, and how this relates
to evolution.
The role of adaptations, variation,
time, reproductive success, and
heritability in evolution.
Types of Evidence
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Evidence for evolution is provided
by 5 scientific principles
Direct observations
The fossil record
Homology
Biogeography
Direct Observations
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Manchester Peppered Moth
Wild guppies w/ plain colors
The common cold and flu
Drug resistant bacteria and viruses
Fossil Record
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Paleontology is the study of
fossils
Fossils are remains or
traces of life in sedimentary
rock
Substantial, but incomplete,
chronicles of evolutionary
history
Transitional fossils have
been found that link ancient
organisms to modern
species
Coincides with
biogeographical
understanding (continental
drift)
Fossil Record
Homology
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Def: traits in related
species can have
underlying similarity
w/ different function
Homologous
Structures:
• structural similarity of
body due to common
ancestry
• functionally dissimilar
Homology
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Embryonic
homologies
are the
notable
anatomical
similarities
in the
embryonic
development
of animals
Homology
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Vestigial Structures: anatomical
structures that ancestors used but
now have reduced (or no) function
Homology
Molecular homology includes a variety of
similarities:
 All organisms share the same genetic
code (DNA/RNA triplets/codon
 The closer related a species, the higher
the percentage of identical DNA
• Chimp and human DNA is 98% identical
• Bird and Human DNA is only 60% identical
• Plant and Human DNA is only 10% identical
Homology
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Convergent Evolution:
unrelated species around
the world look similar
when found in similar
environments (analogous
structures)
Biogeography
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Def: geographic distribution of species
Species tend to be more related to
nearby species
• i.e. desert animals in South America are
more related to local animals in other
habitats than to African desert species
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Continental drift explains the similarity of
species on different continents
Endemic species are species unique to
one specific environment (marine
iguanas)