Molecular Phylogenetics
The Tree of life image that appeared in Darwin’s On
the Origin of Species by Natural Selection, 1859. This
is the only figure in On the Origin of Species.
DNA Mutation
• A change in the
nucleotide sequence of
the genetic material of
an organism
• Create variation in the
gene pool upon which
natural selection can
act
• Only germ line
mutations can be
passed on to
descendants
Causes of DNA Mutations
•
•
•
•
Replication errors
Chemical mutagens
Ionizing Radiation
UV Radiation
Types of DNA Mutations
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Types of Mutations
Insertion
Deletion
Do you think point mutations or
insertions/deletions have greater effects?
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Mutation Rates
• Eukaryotes: 10-4 to 10-6 mutations per base pair
per generation
• Bacteria: 10-8 mutations per base pair per
generation
• Human genome size: 3 billion base pairs
• Bacteria: 0.5-10 million base pairs
Do you think most mutations are harmful?
Beneficial?