Download L3: Evidence for evolution

Evidence of Evolution
Environmental Change
• Earth’s topography and
environment has
changed drastically over
time
– Theory of plate
tectonics
• Earth is old
• Environment is dynamic,
species need to be
dynamic
Evidence for Evolution
Lecture 3
Winter 2014
Evidence of Evolution
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Formation of Fossils
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Fossil
Any trace of an organism
that lived in the past
Fossil Record
– Ordered sequence of
fossils as they appear in
the rock layers
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Dating Fossils
Evidence of Evolution
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Transitional forms
• A fossil species whose traits
are intermediate between
an older and younger
species
See Fig 22.20
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Transitional Forms
Transitional Forms
• Tiktaalik roseae
Model of Tiktaalik
Evidence of Evolution
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Biogeography
• The geographical
distribution of species
• Extinct species in fossil
record were succeeded
by similar living species
Evidence of Evolution
Homologies
• Similarities in characteristics due to descent from
a common ancestor
• Structures are modified to fit new functions
Comparisons at many levels
• Anatomical (structural)
• Developmental
• Molecular (Genetic)
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Evidence of Evolution
Vestigial structures
• Reduced or incompletely
developed structures
• No function or reduced
function in organism
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Evidence of Evolution
• Anatomical (Structural) homologies
– Morphological traits that are similar between organisms
– Modifications not perfect
See Fig. 22.15
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Evidence of Evolution
• Developmental homologies
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• Molecular (Genetic)
homologies
– When newly developing embryos of different species
have a similar trait
– Similarity in the DNA/RNA
sequences
• Closely related organisms have many similar
stages of development
See Fig. 22.16
Homology vs. Analogy
Evidence of Evolution
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• More closely related
organisms will have more
similar nucleotide
sequences in their DNA
Homology vs. Analogy
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• Homology
– Similarity among
organisms due
to shared ancestry
• Analogy
– Similarity among organisms due to adaptations
to similar environments
• Convergent evolution
Evidence of Evolution
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• Evolution is observable within our lifetime
– Antibiotic resistant bacteria
– Insect resistant to pesticides
– Plants resistant to herbicides
– Galapagos finches
• Evolution can be tested experimentally
• Read pgs. 460-462, & Fig. 22.13 & 22.14
(MRSA, soapberry bugs)
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