graham slater's 2013 svp talk
DESCRIPTION
My SVP 2013 talk on modeling mammalian body size evolutionTRANSCRIPT
Graham SlaterDepartment of Paleobiology, National Museum of
Natural History
Tempo or Mode in Evolution? The Case of Mammalian Body
Size Evolution
www.fourdimensionalbiology.com
- Gene Hunt- Pete Wagner- Jon Marcot- Dave Bapst- Tom Ezard- Gavin Thomas- Andy Purvis
- Peter Smits- Greg Wilson
authors
- Luke Harmon*- Rob Freckleton- Sam Ponton
- Arne Mooers- Dave Polly- Folmer Bokma- Graeme Lloyd
organization reviews
data
“Unifying Fossils and Phylogenies for Comparative Analyses of Diversification
and Trait Evolution”
How fast do animals evolve? That is one of
the fundamental questions regarding evolution.
Photo: Florida Museum of Natural History
Simpson (1944, 1953)
is our emphasis on rates appropriate?
Illustration by Mark Hallet
Eoce
ne
Olig
oce
ne
Mio
cene
Alroy (1999) Systematic Biology
fossil data show a rapid increase in body size disparity after the K-Pg
Sd
(m
ass
)
Venditti et al. (2011) Nature
K Pg NgJ
relative rate
phylogenetic data suggest increased rates with the origin of modern
orders
Do we really think the Tempo of mammalian
body size evolution increased after the K-
PG extinction?
the mammalian body size zone
the mammalian body size zone
the mammalian body size zone
variation in tempo
evolution slow
evolution fast
variation in mode
evolution constrained
evolution unconstrained
3 paleo-motivated models for mammalian body size evolution
BM rate 1 BM rate 2
Mesozoic CenozoicK-Pg rate shift
Ornstein-Uhlenbeck BM
Mesozoic Cenozoicecological release
Mesozoic Cenozoicrelease and radiate
BM*Ornstein-Uhlenbeck
time calibrated phylogeny of living and fossil mammals
Estimating body masses for Mesozoic mammals
standard models paleo-inspired models
Brownian motion
directional
evolution
Ornstein-Uhlenbeck
Accelerating /
Decelerating
white noise
K-Pg Shift
ecological
release
release & radiate
extant taxa only
extant + fossils
release & radiate fits best for extant taxa...
standard models paleo-inspired models
Brownian motion
directional
evolution
Ornstein-Uhlenbeck
Accelerating /
Decelerating
white noise
K-Pg Shift
ecological
release
release & radiate
extant taxa only
extant + fossils
...and more so for the fossil dataset
standard models paleo-inspired models
Brownian motion
directional
evolution
Ornstein-Uhlenbeck
Accelerating /
Decelerating
white noise
K-Pg Shift
ecological
release
release & radiate
extant taxa only
extant + fossils
Parameter Mesozoic Cenozoic
rate (σ2) 0.97 0.1
faster rates of body size evolution in the Cenozoic?
Brownian motion is a diversifying process
time
ph
en
oty
pe
rate σ2
starting state starting state
σ2 * time
time
ph
en
oty
pe
σ2 / 2α
rubber band parameter α
OU is an equilibrium process
rate σ2
starting state starting state
time
ph
en
oty
pe
Brownian motionOrnstein-Uhlenbeck
BM and OU simulated at the same rate give very different disparities
the OU process has an equilibrium disparity
ln(b
ody m
ass
) dis
pari
ty
Mesozoic CenozoicT J PgK Ng
α= 0.01σ2 = 0.97
Mesozoic CenozoicT J PgK Ng
a low BM rate increases disparityln
(body m
ass
) dis
pari
ty
σ2 = 0.1α= 0.01σ2 = 0.97
Do we really think the Tempo of mammalian
body size evolution increased after the K-
PG extinction?
Variation in the Mode of evolution is a more intuitive and
more likely explanation that
variation in Tempo
Do we really think the Tempo of mammalian
body size evolution increased after the K-
PG extinction?
How fast do animals evolve? That is one of
the fundamental questions regarding evolution.
Photo: Florida Museum of Natural History
Simpson (1944, 1953)
From Simpson (1953)
Simpson’s adaptive zones