Lying through your teeth: saturation and non independence in morphological data, and what to do about it
1. Lying through your teeth: saturation and non
independence in morphological data, and what to
do about it
Liliana M. Dávalos —Stony Brook University
Paul M. Velazco —American Museum of Natural History
Omar M. Warsi —Stony Brook University
Peter D. Smits —University of Chicago
Nancy B. Simmons —American Museum of Natural History
3. Genome not always
available
•Majority of species are
extinct
•Fossils are all that
remain
•Phylogenies must use
morphology
•How?
Morgan Czaplewski 2012 Evolutionary
History of Bats
4. Total evidence Conditional combination
Hermsen Hendricks 2008 Ann Missouri Springer et al. 2007 Syst Biol
Bot Gard
5. Assumptions of
phylogeny
•Homology: character
changes reflect
common descent
•IID: Independent and
Identically Distributed
7. Saturation is not
everything
•If rates of evolution are
high, then signal
erased over time
•Results in
unresolved
phylogeny
•Other signal must
emerge to resolve
phylogeny
• First position
• Second position
o Third position
Dávalos Perkins 2008 Genomics
10. 19
9.5
0
3.9
2.6
1.3
0
Molecular Morphological
Frequency (percent)
A
Figure B
Pairwise dissimilarity between characters
Relative density between morphological characters
0.0 0.2 0.4 0.6 0.8 1.0
2.5
2.0
1.5
1.0
0.5
0.0
Signal is amplified by
repetition
•Measured dissimilarity
between pairs of
characters
•25% sequence
characters are
completely dissimilar
•Despite protein-coding
loci
•This is not the case for
dental characters
Dávalos et al. Accepted Syst Biol
12. Data models don’t
match
•Less is more when
collecting certain kinds of
characters
•Dental data violate key
assumptions of
phylogenetic models
•Saturation, convergence,
and non-independence
•= model failure
•New data models needed
Czaplewski et al. 2003 Caldasia
14. Thanks!
• Funding
• NSF—DEB
• CIDER—SBU
• Speciation diversification: A.
Cirranello, E. Dumont, A. Russell,
N. Simmons, P. Velazco
• N. Gerardo, A. Wilson
• Dávalos Lab
• Phylogenetics: B. Baird, S.
DelSerra, A. Goldberg, O.
Warsi, L. Yohe