morphospace

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time
morphospace
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time
morphospace
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Phylogenetic reconstruction Morphological
characters Molecular characters rRNA genes,
mtDNA/cpDNA, nuclear genes Ancestral descendent
Outgroup character polarity
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1 2 3 4
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Monophyletic Paraphyletic
Polyphyletic all descendents of
some, but not all, shared character
common ancestor descendents
not present in possess trait possess
trait common ancestor
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Monophyletic Paraphyletic
all descendents of some, but not
all, common ancestor
descendents possess trait possess
trait
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abcdefg abcdefg
abcdefg abcdefg
A B C D
A B C D
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abcdefg abcdefg
abcdefg abcdefg
A B C D
A B C D
a is shared ancestral
a a
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abcdefg abcdefg
abcdefg abcdefg
A B C D
A B C D
b b
c c
a is shared ancestral b and c are shared
derived d e f and g are uninformative
a a
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A B C C B A
B A C
3 species -- 3 possible trees 3 known, plus 4th
-- 15 possible trees 3 known, plus 10 --
282,137,824 possible trees plus 20 -- gtgt81023
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Parsimony -- topology that minimizes total
evolutionary change
Consider 4 taxa, trait is one codon 1.
GAA 2. GAA 3. GAT 4. GAT
1. GAA 3. GAT 1. GAA 2. GAA
A
A
vs
A T
T
T
2. GAA 4. GAT 3. GAT 4. GAT
problem -- multiple most parsimonious
trees many branches -- local optimum vs.
global optimum
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Sequence of character change Evolution of
hammerhead sharks Two hypothesized functions
- bowplane to increase lift while swimming
- enhanced orientation and prey
detection Martin 1997 Nature 364494
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Gopher and louse phylogenies are significantly
congruent
pocket gophers lice
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The timing of diversification is significantly
correlated in gophers and lice