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2006-2007
Evidence forEvolution
by Natural Selection
Vocabulary
AnalogousConvergent evolutionEmbryoHomologousVestigial
What are the lines of evidence that support Darwin’s ideas?…
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LampreyFrogBirdDogMacaqueHuman
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Evidence of EvolutionDarwin argued that life on earth has
been evolving for millions of years. 1. Artificial Selection2. The Fossil Record3. Geographical location4. Anatomical evidence 5. Similarities in Early Development 6. DNA and protein similarities
(newer evidence)
What are the lines of evidence that support Darwin’s ideas?
Terminalbud
Lateralbuds
Brussels sprouts
Cabbage
Flower cluster Leaves
Cauliflower
Flowerandstems
Broccoli Wild mustard Kohlrabi
Stem
Kale
1)Artificial selection
Selective breeding
the raw genetic material (variation) is hidden there
What are the lines of evidence that support Darwin’s ideas?
2) Fossil record
Millions of years ago
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Equus
HyracotheriumMesohippus
Merychippus
Nannippus
Bo
dy
size
(kg
)
The Fossil Record
Evidence for Evolution – The Fossil Record
The Fossil Record Showed that:
There have been countless species that have lived on earth but no longer live on earth today
Layers of rocks with fossils demonstrated that thousands, or even millions of years were needed to create this
Species have changed in appearance and complexity
The fossil record
The giant sloth
Evolution of birds
Smithsonian Museum, Washington, DC
Archaeopteryx lived about 150 mya links reptiles & birds
Evolution of land animals 2006 Fossil Discovery of Early Tetrapod
“Tiktaalik” “missing link” from sea to land animals
from swimming (0 legs) to walking (4 legs)
3. Geographic Distribution of Living Species
Animals that are related to each other showed ‘descent with modification’ based on their environment (even though probably closely related, looked different because different environment
Animals that were not related to each other looked similar if they were from similar environments.
Geographic Distribution of Living Species
Desert Fox Koala Dingo
Example: Based on what they look like: Which two animals do you think are more
closely related to one another?
Geographic Distribution of Living Species
Desert Fox Dingo
•Believed to not be closely related to each other even though they look more alike.
•Evolutionists say they look alike because they live in the same kind of environment so over time they adapted
in similar ways
Analogous structures
Dissimilar anatomy doing a similar functionDissimilar anatomy doing a similar function
Does this mean they have a
recent common ancestor?
Don’t be fooledby their looks!
Those fins & tails & sleek bodies are
analogous structures!
Convergentevolution
marsupial mammalsmarsupial mammals
placental mammalsplacental mammals
Convergent evolutionThese animals
look very similar but doesthat mean they have a
recent common ancestor?
What is thisevidence of?
4) Anatomical evidence
What are the lines of evidence that support Darwin’s ideas?
Homologous Structures Arms, wings, legs, and flippers
all have very similar bones Similar in anatomy doing
different potentially different functions
Darwin believed this was evidence that all species were original descended from one common ancestor.
spines
tendrilssucculent leaves
Homologous structures
leaves
needles
colored leaves
Vestigial organs Why would whaleshave pelvis & leg bones
if they were alwayssea creatures?
These areremnants of
structures that werefunctional in
ancestral speciesHumansAppendixCoccyx
Wisdom TeethDarwin’s Tubercle (ear)
Palmaris LongusGoose bumps
Pseudogenes – L-gulonolactone oxidase
Vestigial Organs
HumansAppendixCoccyxWisdom TeethDarwin’s Tubercle (ear)Palmaris LongusGoose bumps
5. Similarities in Early Development
Looking at the embryonic
development of organisms Darwin
noticed some similarities that other scientists also noticed.
Evidence for Evolution - Comparative Embryology
Why do embryos of different animals pass through a similar developmental stage?
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LampreyFrogBirdDogMacaqueHuman
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Why compare DNA & proteins across species?
6. Putting it all together with DNA evidence
Why comparethese genes?
Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans
Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans
compare common genes cytochrome C (respiration) hemoglobin (gas exchange)
compare common genes cytochrome C (respiration) hemoglobin (gas exchange)
The sequence in DNA & proteinsis a molecular
record of evolutionaryrelationships.
Comparative hemoglobin structure
Building “family” trees
