1. Evidence for Evolution by Natural Selection
Hunting for evolution clues… Elementary, my dear, Darwin!

2. 1. Fossil record Layers of rock contain fossils
new layers cover older ones
creates a record over time
fossils show a series of organisms have lived on Earth
over a long period of time

3. Life on Earth has changed
Fossils tell a story…
the Earth is old
Life is old
Life on Earth has changed

4. Evolution of birds Today’s organisms descended from ancestral species
Fossil of Archaeopteryx
lived about 150 mya
links reptiles & birds
The avian nature of the brain and inner ear of Archaeopteryx (Alonso et al. 2004) - Archaeopteryx, the earliest known flying bird from the Late Jurassic period, exhibits many shared primitive characters with more basal coelurosaurian dinosaurs (the clade including all theropods more bird-like than Allosaurus), such as teeth, a long bony tail and pinnate feathers. However, Archaeopteryx possessed asymmetrical flight feathers on its wings and tail, together with a wing feather arrangement shared with modern birds. This suggests some degree of powered flight capability but, until now, little was understood about the extent to which its brain and special senses were adapted for flight. Alonso et al. (2004) investigated this problem by computed tomography scanning and three-dimensional reconstruction of the braincase of the London specimen of Archaeopteryx. A reconstruction of the braincase and endocasts of the brain and inner ear suggest that Archaeopteryx closely resembled modern birds in the dominance of the sense of vision and in the possession of expanded auditory and spatial sensory perception in the ear. Alonso et al. (2004) concluded that Archaeopteryx had acquired the derived neurological and structural adaptations necessary for flight. An enlarged forebrain suggests that it had also developed enhanced somatosensory integration with these special senses demanded by a lifestyle involving flying ability.

5. We found the fossil — no joke!
Land Mammal ?
Complete series of transitional fossils ?
Where are the intermediate fossils? ? ?
There are innumerable intermediate & transitional forms
Whales as land creatures returning to the water….
Where are the intermediate forms of whale ancestors?
Cartoon making fun of this idea.
The cartoons disappeared years ago when this fossil was found.
Ambilocetic natans = “Walking whale who likes to swim”
4-5 intermediate forms all found in last 2 decades
Indus River valley in between India & Pakistan.
Someone’s idea of a joke!
Ocean Mammal
But the joke’s on them!!

6. 2. Anatomical record Animals with different structures on the surface
But when you look under the skin…
It tells an evolutionary story of common ancestors

7. A. Homologous structures
Structures that come from the same origin
homo- = same
-logous = information
Forelimbs of human, cats, whales, & bats
same structure
on the inside
same development in embryo
different functions
on the outside
evidence of common ancestor

8. Compare the bones The same bones under the skin
limbs that perform different functions are built from the same bones

9. But don’t be fooled by these…
B. Analogous structures
look similar
on the outside
same function
different structure & development
on the inside
different origin
no evolutionary relationship
Solving a similar problem with a similar solution

10. Analogous structures Dolphins: aquatic mammal Fish: aquatic vertebrate
both adapted to life in the sea
not closely related

11. C. Vestigial organs Structures on modern animals that have no function
remains of structures that were functional in ancestors
evidence of change over time
some snakes & whales have pelvis bones & leg bones of walking ancestors
eyes on blind cave fish
human tail bone

12. Vestigial organs Hind leg bones on whale fossils
Why would whales have pelvis & leg bones if they were always sea creatures?

13. They just came up with the same answer!
Flight evolved 3 separate times —
evolving similar solutions to similar “problems”
Convergent evolution
3 groups with wings
Does this mean they have a recent common ancestor?
They just came up with the same answer!
NO!

14. filling similar roles in nature, so have similar adaptations
Parallel Evolution
not closely related
marsupial
mammal
placental
filling similar roles in nature, so have similar adaptations

15. 3. Comparative embryology
Development of embryo tells an evolutionary story
similar structures during development
all vertebrate embryos have a “gill pouch” at one stage of development

16. “descendants” of wild mustard
4. Artificial selection
How do we know natural selection can change a population?
we can recreate a similar process
“evolution by human selection”
“descendants” of wild mustard

17. “descendants” of the wolf
Selective Breeding
Humans create the change over time
“descendants” of the wolf

18. 5. Molecular record Comparing DNA & protein structure
everyone uses the same genetic code!
DNA 10 20 30 40 50 60 70 80 90
100
110
120
Lamprey
Frog
Bird
Dog
Macaque
Human 32 8 45 67
125
compare common genes
compare common proteins
number of amino acids different from human hemoglobin

19. Building “family” trees
Closely related species are branches on the tree — coming from a common ancestor

20. Evidence supporting evolution
1.Fossil record
shows change over time
2.Anatomical record
comparing body structures
Homology, analogous, vestigial
3. Embryology
Comparing embryos
4.Artificial selection
human caused evolution
5.Molecular record
comparing protein & DNA sequences

21. Any Questions??