My SVP 2013 talk on modeling mammalian body size evolution

1. TempoorMode in Evolution?
The Case of Mammalian Body
Size Evolution
Graham Slater
Department of Paleobiology, National Museum of Natural
History
www.fourdimensionalbiology.co
m

2. “Unifying Fossils and Phylogenies for
Comparative Analyses of Diversification and
Trait Evolution”
organization
- Luke Harmon*
- Rob Freckleton
- Sam Ponton
authors
- Gene Hunt
- Pete Wagner
- Jon Marcot
- Dave Bapst
- Tom Ezard
- Gavin Thomas
- Andy Purvis
reviews
- Arne Mooers
- Dave Polly
-FolmerBokma
- Graeme Lloyd
data
- Peter Smits
- Greg Wilson

4. How fast do
animals evolve?
That is one of the
fundamental
questions
regarding
evolution.
Simpson (1944,
Photo: Florida Museum of Natural
History

5. is our emphasis on
rates appropriate?

6. Illustration by Mark Halle

7. Eocene
Oligocene
Miocene

8. Sd (mass)
fossil data show a rapid increase in body
size disparity after the K-Pg
K
Pg
Ng
Alroy (1999) Systematic Biology

9. phylogenetic data suggest increased rates
with the origin of modern orders
relative
rate
J
K
Pg
Ng
Venditti et al. (2011) Natur

11. Do we really think the
Tempoof mammalian
body size evolution
increased after the K-PG
extinction?

13. the mammalian body size zone

14. the mammalian body size zone

15. the mammalian body size zone

16. variation in tempo
evolution
fast
evolution slow

18. variation in mode
evolution
unconstrained
evolution constrained

19. 3 paleo-motivated models for
mammalian body size evolution
K-Pg rate shift
Cenozoic
BM rate 1
ecological release
Mesozoic
BM rate 2
Mesozoic
Cenozoic
Ornstein-Uhlenbeck
release and radiate
Mesozoic
BM
Cenozoic
Ornstein-Uhlenbeck BM*

20. time calibrated phylogeny of living and
fossil mammals

21. Estimating body masses for Mesozoic
mammals

22. extant taxa only
extant + fossils
Brownian
motion
directional
evolution
Ornstein- Accelerating /
Uhlenbeck Decelerating
standard models
white
noise
K-Pg Shift
ecological
release
release &
radiate
paleo-inspired models

23. elease & radiate fits best for extant taxa..
extant taxa only
extant + fossils
Brownian
motion
directional
evolution
Ornstein- Accelerating /
Uhlenbeck Decelerating
standard models
white
noise
K-Pg Shift
ecological
release
release &
radiate
paleo-inspired models

24. ...and more so for the fossil dataset
extant taxa only
extant + fossils
Brownian
motion
directional
evolution
Ornstein- Accelerating /
Uhlenbeck Decelerating
standard models
white
noise
K-Pg Shift
ecological
release
release &
radiate
paleo-inspired models

25. faster rates of body size evolution in
the Cenozoic?
Parameter Mesozoic Cenozoic
rate (σ2)
0.97
0.1

26. phenotype
Brownian motion is a diversifying
process
starting state
starting state
rate σ2
σ2 * time
time

27. phenotype
OU is an equilibrium process
starting state
starting state
σ2 / 2α
rate σ2
rubber band parameter α
time

28. BM and OU simulated at the same rate give
very different disparities
phenotype
Brownian motion
Ornstein-Uhlenbeck
time

29. ln(body mass) disparity
the OU process has an equilibrium
disparity
α= 0.01
2 = 0.97
σ
T
J
Mesozoic
K
Pg
Ng
Cenozoic

30. ln(body mass) disparity
a low BM rate increases disparity
2=
σ
α= 0.01
2 = 0.97
σ
T
J
Mesozoic
K
Pg
0.1
Ng
Cenozoic

31. Do we really think
Variation in the Mode of
theTempoof mammalian
evolution is a more
body size evolution
intuitive and more likely
increased after the K-PG
explanation that variation
extinction?
in Tempo

32. Do we really think the
Tempoof mammalian
body size evolution
increased after the K-PG
extinction?

33. How fast do
animals evolve?
That is one of the
fundamental
questions
regarding
evolution.
Simpson (1944,
Photo: Florida Museum of Natural
History

35. Simpson’s adaptive zones
From Simpson (1953)