45
Evidence for Evolution A slide extravaganza…
Evidence for Evolution
A slide extravaganza…
Types of evidence…
1. Evidence from the fossil record (dead things)
Fossil formation
Bones and shells undergo mineral replacement and are turned into rock
Soft material either disappears, or leaves an impression in the earth (that turns to rock)
A selection of fossils…
Fossils show transitions
The Archaeopterix -- between reptile and bird
Scallops
From early to modern horse
(Living things show transitions too)
Coelacanths - “the living fossil”
Types of evidence…
1. Evidence from the fossil record
Types of evidence…
1. Evidence from the fossil record2. Comparative Anatomy
A. Homologous Structures
Homo - logy
Homologous structures have the same underlying forms
Wing anatomy comparison
And compared to our arm…
Arm anatomy comparison
B. Analogous Structures
Ana - logy
Analogous structures have a similar outward appearance (but different underlying forms)
Types of evolution
Convergent evolution Distantly related organisms evolve similar external features
Divergent evolution A common ancestor gives
rise to organisms that evolve for different environments
Which goes with which? ….
Homologous structures
Analogous structures
Convergent evolutionDistantly related
organisms evolve similar external features
Divergent evolution A common ancestor
gives rise to organisms that become more different with time.
Which goes with which?
Homologous structures
Analogous structures
Convergent evolutionDistantly related
organisms evolve similar external features
Divergent evolution A common ancestor
gives rise to organisms that become more different with time.
C. Vestigial Structures
Vestige - a left-over/ remnant
Vestigial structures are evolutionary “leftovers” from an earlier ancestor
The “dew” claw of a wild cat
The human appendix
Rabbit Fetal Human Adult Human
Membranes in our eyes
Hip bones in whales
(Look at that “hand” too!)
Types of evidence…
1. Evidence from the fossil record2. Comparative Anatomy
Types of evidence…
1. Evidence from the fossil record2. Comparative Anatomy 3. Comparative Embryology
Human embryo at 5 weeks
Embryos…
…can you guess which one is human?
…how about now?
Embryos…
And now…
Were you right?
Types of evidence…
1. Evidence from the fossil record2. Comparative Anatomy 3. Comparative Embryology
Types of evidence…
1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence
Comparing DNA…
Determining relationships
DNA similarity between species is used to determine how closely related they are.
This is in turn used to construct possible evolutionary trees.
How closely related are these fellows?
Giant Panda
Brown Bear
Mystery critter! (I’m not telling)
…got your guess?
An Evolutionary Tree
…so why is he called a red panda?
This tree was constructed by looking at % similarity of DNA among “bears”
Types of evidence…
1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence
Types of evidence…
1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior
Behavioral similarities
Duck and other bird mating dancesHow primates carry their youngFish swimming motions and salamander
walksAnd on and on and on….
Types of evidence…
1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior
Types of evidence…
1. Evidence from the Fossil Record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior6. Direct observation
also known as microevolution
Artificial selection
Remember us?
And look at us!
And Natural Selection
Hawaiian Rock Wallabies!
The Beak of the Finch
Biologists Peter and Rosemary Grant documented natural selection occurring in populations of finches on the Galapagos islands over a period of only 20 years! This generation to generation changes in the frequency of certain traits is called microevolution.
