Transcript Blue_line_phylo_intro

Introductory Phylogenetics and the Blue
line in DNA Subway
Sheldon McKay
DNALC, Cold Spring Harbor Laboratory
March 28, 2012
Why is the tree of life important?
“Knowledge of evolutionary relationships is
fundamental to biology, yielding new insights
across the plant sciences, from comparative
genomics and molecular evolution, to plant
development, to the study of adaptation,
speciation, community assembly, and
ecosystem functioning.”
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Tree of Life: Classification and Phylogeny
Image from http://tolweb.org/tree
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We have a tendency to put things into categories.
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Classifications often reflect evolutionary history
F
B
A
D
C
E
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Phylogenetic trees are representations of evolutionary history
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2007
evolution
77,816
100%
ecolog*
62,761
82%
phylogen*
29,282
38%
ecolog*
evolution
phylogen*
Figure courtesy of Brian Omeara
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What is the difference between taxonomy and phylogeny?
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Consider primates: Do humans make up a monophyletic group?
Hylobatidae
Pongidae
Hominidae
(E) human
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Phylogeny based on a globin pseudogene suggests that
humans and chimpanzees make up a single monophyletic group
outgroup
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Are there practical uses for phylogenetics?
Consider the “Tripoli Six”
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Are there practical uses for phylogenetics?
Six Medical aid workers who arrived in Libya were accused of causing an
HIV outbreak amongst 400 children at a Libyan hospital.
Forensic phylogenetic analysis showed that the strains of HIV and HCV were
prevalent in the hospital well before the team arrived in 1990
The six were convicted and sentenced to death anyway. They were later
re-tried and sentenced to life. They were eventually released.
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Trait Evolution
Image courtesy of Brian Omeara
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Are the “Camera eyes” in molluscs and vertebrates homologous?
Rotifera
Platyhelminthes
Annelida
Mollusca
Nematoda
Arthropoda
Echinodermata
Vertebrata
gain
gain
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http://phe.rockefeller.edu/barcode/blog/wp-content/uploads/2006/12/titmice-tree2.gif
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Phylogenetic tree as a reference for barcode-based
species identification
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Phylogenetic tree as a reference for barcode-based
species identification
? Barcode x
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The Blue Line
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