03/15/06
From Biol301
*Notes compliment of E.H-M.
The molecular clock (cont'd)
- use fossil evidence to clabirate
- example: panda / bear
- split 20 million years ago
- 10% difference
- (%difference) / (millions of years ago) = (%change per million years)
- (10%) / (20mya) = (0.5%) change per million years
- so if we find that brown bear and polar bear are 0.25% different
- a rearrangement shows: (%difference) / (%change per million years) = (millions of years ago)
- such that (0.25%) / (0.5%) = (0.5) mya
Building Trees
Step1: Obtain DNA sequences
Step2: Build Phylogenies using DNA data
Step2a: Use genetic distances
Step2b: Use parsimony to make tree with fewest mutations necessary
Using Trees
- Reconstruct ancestral characteristics
- Behavior
- Morphology
- Geographic range
- Molecular sequences
- Example: Altimara plumage type represents divergence
- Bright vs. dull males
- Keep in mind different genes and different lineages have different rates of change (rates of evolution)
