1. The Evidence for Evolution

2. Vestigial Structures Features that have no apparent function
Typically have an important function in related spp.
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Vestigial structures
Ex: Hindlimb joints in whales and snakes

3. Vestigial Structures in Humans
Tailbone
Wisdom Teeth
Appendix

4. DNA 1. Chromosome banding patterns, comparing living groups
2. Amino acid sequences in proteins, comparing living groups
3. Base pair sequences in DNA, comparing living groups
4. Comparative anatomy studies of different groups
5. Comparative studies of development of different groups

5. Darwin’s Theory of Evolution by Natural Selection
Species have changed through time and are related by descent from a common ancestor
The primary mechanism of Evolutionary Change is Natural Selection

6. Fossil Record
The fossil record is the history of life recorded by remains from the past. Most fossils are at least 10,000 years old.
Body Fossils
Trace Fossils

7. - Fossils exist and fossil forms are unlike species living today
What is found?
- Fossils exist and fossil forms are unlike species living today
1. Fossil Sequence?
When fossils are arranged according to
their age, they show successive
evolutionary change
2. Fossil Intermediates?
Transitional fossils have been found between:
Amphibians & reptiles, reptiles & birds,
reptiles & mammals, apes and humans

8. The fossil Record is Incomplete
At the time of Darwin, the fossil record was VERY scanty. A great deal of progress has been made since, but it is far from finished.
The fossil record is relatively incomplete for several reasons:
1. Soft tissues are rarely preserved
2. Movement of the earth's crust has obliterated and/or covered many fossils
3. Fossilization takes place only in certain types of habitats and favorable environments
4. Paleontologists have not dug up every place on earth

9. Evidence for the Relatedness of Life Forms?
Hypothesis: all living organisms have descended from a common ancestor
Prediction: we should also be able to see evidence of relatedness of species
-Homology
-Geographic distribution

10. Homology
Homology: a similarity between species that is the result from the inheritance of traits from a common ancestor
The features of every creature reflect history as well as adaptation
3 types of homologies
- structural
- developmental
- genetic

11. Homologous structures: bones of the forelimb
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Homologous structures: bones of the forelimb
The underlying design of each structure is similar despite
their functional differences

12. Homology vs. Analogy
Natural selection appears to have favored similar adaptations
in unrelated organisms in similar environments-->
these structures are analogous
Whereas homologous structures
share structural similarity, but not function, analogous structures share function but not structural similarity since they evolved independently

13. Adaptation in response to environment or competition

14. Convergent Evolution--adaptation

15. Embryos show evolutionary history
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Embryos show evolutionary history
Homologous structures in adults develop from homologous groups
of cells in embryos --> they share developmental pathways

16. Genetic Homologies All living organisms share the same genetic code
Chromosome and gene similarities between
species match evolutionary similarities
This is true for both coding regions and
“junk DNA”

17. Molecules reflect evolutionary divergence

18. Geographic Distributions
Species that are extremely similar to one another tend to be
clustered geographically (Ex.: Darwin’s finches)
Living species are more similar to fossil species in the same area
than they are to living species in other areas
The law of succession
general correspondence between fossil and living forms in same geographical area
Darwin used this observation to predict that fossils
of ancient humans should be found in Africa