1. Direct Evidence for Evolution
Fossil Record
Paleontologists have collected millions of fossils that make up the fossil record
The fossil record is incomplete as many organisms die and vanish without leaving a trace
Does give a relatively clear picture of change.
Ex. Evolution of the Horse

2. Direct Evidence for Evolution
Fossils
Preserved remains or traces of an organism that lived in the past.
Fossils are formed when organisms die and are buried in sediment. Eventually the sediment builds up and hardens to become sedimentary rock.

3. Direct Evidence for Evolution
Fossil Record
Shows major changes in Earth’s climate and geography
i.e. Fossil shark teeth found in Arizona, indicating it was once covered by a sea
Fossils can be absolute dated using radioactive decay of nearby flows
They can be relative dated using nearby clues

4. Indirect Evidence for Evolution
Homologous Structures
Modified body parts with different functions that developed from the same ancestral parts
Embryological Relationships
Structural similarities between species during embryonic development
i.e. Gill slits in humans

5. Indirect Evidence for Evolution
Vestigial Structures
Structures in the body of organisms that seem to serve no useful purpose at all
May have had a function in ancestral forms
Eg. human tailbones, the appendix
Muscles that move our ears
Whale hip bones

6. Indirect Evidence for Evolution
Comparative biochemistry
All organisms have similarities in their biochemistry
All life uses DNA, ATP, Carbon
The more closely two species are related, the closer the similarities between their genes
Humans share: 98% of our genes with chimpanzees; 65% with chickens; 60% with bananas; 7% with bacteria

7. The Patterns of Evolution

8. Divergent Evolution
Reproductive Isolation often results in Divergent evolution
The process by which one species gives rise to two or more new species, whose traits become more and more different, but who share a common, structural ancestor
Produces homologous structures
Different function, but same origin

9. Convergent Evolution
The process by which two or more different species evolve to become structurally similar
Species must have similar niches
Ex. shark and dolphin
Produces analogous structures
Similar function, but different origin

10. Parallel Evolution
The process where two different species follow similar evolutionary paths
Species must have similar niches
Ex. Timber wolf and Tasmanian wolf
Sleek, hunters, etc…

11. Co-evolution
When two or more species influence each other's evolution.
It is most often invoked to explain co-adaptations between species.
Ex: Parasites and Hosts
(antagonistic coevolution)
can lead to evolutionary 'arms races‘
Ex: Insects and Flowering Plants
(mutualistic coevolution)

12. Living Fossils
Some organisms have changed very little over the past million years
E.g. Ginko biloba (270 MYA)
Hagfish (300 MYA)
Red Panda (10 MYA)
Pelicans (30 MYA)
Crocodiles (83.5 MYA)