Lecture 13 - Molecular Systematics Flashcards
Molecular trees can resolve both _____ and _____ divergence
ancient, recent
How can molecular trees resolve diverge?
by using molecules that evolve at different rates
What resolves deep divergences?
conserved sequences
What is an example of a conserved sequence?
ribosomal RNA
What is a benefit of using additional genes?
gives a more complicated view
What resolves more recent divergence?
mitochondrial DNA
What are the two types of homologous genes that molecular phylogenies rely on?
- orthologous
2. paralogous
What is orthologous?
found in different species as a result of speciation (product of speciation)
What is paralogous?
found in the same genome as a result of gene duplication (within a species)
How do molecular phylogenies track evolutionary time?
if we assume a molecular clock
What is a molecular clock?
- using phylogenies to estimate evolutionary time of divergence
- molecular yardstick
What is the basis of the molecular clock?
- yardstick for measuring absolute time of an evolutionary change
- based on observation that some genome regions appear to evolve at constant rates
What is the Neutral Theory?
- states that much evolutionary change in genes/proteins has no effect on fitness
- therefore not influence by Darwinian selection
- states that rate of molecular change in genes/proteins should be regular like clock
Who was Motoo Kimura?
developed the Neutral Theory
What are 3 flaws to molecular clocks?
- imprecise
- rates vary among genes and among species
- clock rates need to be calibrated with independent data
