Whitaker 5 3-4-11 - Office Hours Friday 3:00-4:00 Tuesday...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Office Hours Friday 3:00-4:00 Tuesday 1:00-2:00
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Molecular fossils In order to use DNA sequences to reconstruct evolutionary history we need to understand what forces act upon the random mutations
Background image of page 2
Evolutionary processes Mutation - introduces variation in to a population. This is a random process. Selection - removes variation by replacing less adaptive variants with more adaptive alleles or removing maladaptive variants Genetic drift - removes variation randomly Gene flow - the movement of variation within and between populations. Recombination or horizontal gene transfer Migration or dispersal
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
What happens to the random mutation? Random mutation Negative (Purifying) Selection Mutation is removed by negative selection 1:16 16:16 Variable Not variable This happens most often - most change is bad
Background image of page 4
What happens to the random mutation? Random mutation Increase in frequency because it is adaptive 1:16 8:16 16:16 Variable Not variable polymorphic monomorphic Positive Selection
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
What happens to the random mutation? Positive Selection Random mutation 1:16 8:16 16:16 Variable Not variable Mutation is fixed into a population but variation is still removed
Background image of page 6
Selection Positive selection: fitness increases eventually everyone has the new adaptive sequence. Negative selection: fitness decreases so that maladaptive mutations are lost. Diversifying selection select for multiple types Most selection is negative selection
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
When infected with extensively drug resistant MTB less than 30% of patients are cured Mycobacterium tuberculosis (MTB) Antibiotic resistance
Background image of page 8
Streptomycin binds to 16S rRNA and interferes with translation MTB can go from 2% to 80% resistant in 3-4 months. This is positive selection increasing the frequency of the mutation.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
There are no pathogenic archaea, but if there were would streptomycin work as an antibiotic?
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 46

Whitaker 5 3-4-11 - Office Hours Friday 3:00-4:00 Tuesday...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online