SSB2017 lightning talk

1. Fossilized birth-death dating in
Formicidae
April Wright
Tuesday, Jan. 10
Systematic Biology Standalone Meeting
@wrightingapril
William ChoSteve Shattuck

2. Towards a better timetree of ants
● 666 multi-gene DNA sequences (Blanchard and
Moreau 2016)
● 138 extant ant specimens with morphological
characters coded (Keller 2014)
● 42 fossil ant specimens with morphological
characters coded (Barden and Grimaldi 2016)
● 800 fossil ant specimens with age information

3. Towards a better timetree of ants
● 666 multi-gene DNA sequences (Blanchard and
Moreau 2016)
● 138 extant ant specimens with morphological
characters coded (Keller 2014)
● 42 fossil ant specimens with morphological
characters coded (Barden and Grimaldi 2016)
● 800 fossil ant specimens with age information

4. Fossils and Phylogeny
● Small data
● Unlikely to collect
more data
● Models likely
inadequate
Wright and Hillis 2014; Wright, Lloyd and
Hillis 2016
Genetic Data in
Phylogenetics
● Large datasets of DNA
● Tractable to collect
more data
● Computational tools
likely inadequate
William Cho

5. Fossils and Phylogeny
● Small data
● Unlikely to collect
more data
● Models likely
inadequate
Wright and Hillis 2014; Wright, Lloyd and
Hillis 2016
Genetic Data in
Phylogenetics
● Large datasets of DNA
● Tractable to collect
more data
● Computational tools
likely inadequate
William Cho

6. Fossils and Phylogeny
● Small data
● Unlikely to collect
more data
● Models likely
inadequate
William Cho
A C
G T

7. William Cho
A C
G T
01
0
1
0
0
1
0
0
0
10
1
0
0
1
0
0
0
Paul Lewis 2001

8. When this assumption
is violated, this can
severely distort our
ability to uncover the
true evolutionary history
Wright, Lloyd, and Hillis 2016
William Cho
A C
G T
01
0
1
0
0
1

9. Photo: Steve Shattuck
Sphecomyrminae

10. Sphecomyrminae
● Presence of
wasp-like features
that are lost after
divergence of
Sphecomyrminae
from the rest of
the ants
Photo: Steve Shattuck

11. Sphecomyrminae
● Presence of
wasp-like features
that are lost after
divergence of
Sphecomyrminae
from the rest of
the ants
● Presence of ant
apomorphies
Photo: Steve Shattuck

12. Sphecomyrminae
● Presence of
wasp-like features
that are lost after
divergence of
Sphecomyrminae
from the rest of
the ants
● Presence of ant
apomorphies
= bad fit of character
change symmetry
assumptionPhoto: Steve Shattuck

13. Relaxing Character Change Symmetry
● MrBayes used a symmetric Beta distribution ( α = β)
prior on state frequencies to allow for variation in
character change symmetry

14. 14

15. 15
Default
Mk
model

17. RevBayes

18. RevBayes
RelativeProbability
0 to 1 Transition Rate 0 50 100
1 to 0 Transition Rate 100 50 0
β ≠ α

19. Resulting phylogeny largely
congruent with previous
morphological trees

20. Resulting phylogeny largely
congruent with previous
morphological trees
Usage Example: RevBayes:
Analysis of Fossil and Molecular
data

21. Thank You
Will Pett
Tracy Heath
Ben Blanchard
Corrie Moreau
Roberto Keller
Philip Barden
1612858