Tooth wear - causes and (evolutionary) consequences
review of the evidence
Thomas Kaiser, Ellen Schulz Zoological Museum, University of Hamburg, Germany
Jürgen Hummel Animal Nutrition Group, University of Bonn, Germany
Dennis Müller, Marcus Clauss Clinic for Zoo Animals, Exotic Pets and Wildlife, University of Zurich, Switzerland
NESCent Symposium 2011
Tooth wear
•!Do animals show adaptations to tooth wear?
•!Do variations in tooth wear drive the quantitative expression of these adaptations?
•!Hypsodonty, mesowear, tooth wear (height/volume per time)
•!Diet abrasiveness
Hypsodonty and grass
own evaluation, but similar findings published by Janis (1995), Perez-Barberia and Gordon (2001), Mendoza and Palmqvist (2008)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Pro
port
ion e
xcessiv
e w
ear
fed from dishes/racks
fed on sandy soil
from Healey et al. (1965)
0
0.1
0.2
0.3
0.4
0.5
0.6
0 50 100 150 200 250
Soil ingestion (g/d)
Incis
or
length
(in
.)
Soil ingestion and wear
from Healey et al. (1966)
0
5
10
15
20
25
30
35
40
45
0 2 4 6 8 10
Month
Wear
in p
recedin
g 6
weeks
(in.)
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Faecal s
oil (%
DM
)
Faecal soil (%DM)
Wear
Soil ingestion and wear
Foto: Johanna Castell
method developed by Fortelius, Solounias (Kaiser)
=0
=1
=2
=3
=4
Free-ranging vs. captive giraffes
from Clauss et al. (2007)
from Clauss et al. (i2007)
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
Diffe
rence in s
core
Less abrasion than in the wild
More abrasion than in the wild
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
0 1 2 3 4 5 6
Hypsodonty index
Diffe
rence in s
core
BR
IM
GR
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100
%grass
Faecal silic
a (
mg/k
g D
M)
dry season
wet season
R2 = 0.66
0
1
2
3
4
5
6
7
8
9
10
0 50 100 150
Faecal silica (mg/kg DM)
Hypsodonty index
0
1
2
3
4
5
6
0 1 2 3 4 5
Annual wear rate (mm)
Hypsodonty
index
0
1
2
3
4
5
6
0 1 2 3 4 5
Annual wear rate (mm)
Hypsodonty
index
0
1
2
3
4
5
6
0 1 2 3 4 5
Annual wear rate (mm)
Hypsodonty
index
Testing the mesowear signal
•!Species level (comparative) •!Calculating mesowear score from Fortelius & Solounias (2000) and the data collection of Kaiser; matching hypsodonty index from Janis (1988)
•!Using %grass from own data collection •!Using habitat score from Mendoza & Palmqvist (2008)
•!Using precipitation and other climate data from Pantheria
•!Analyses with OLS and PGLS
R2 = 0.66
0
1
2
3
4
5
6
7
0 50 100 150
Faecal silica (mg/kg DM)
Hypsodonty index
Mesowear score
Is diet abrasiveness reflected in the mesowear score?
R2 = 0.66
0
1
2
3
4
5
6
7
0 50 100 150
Faecal silica (mg/kg DM)
Hypsodonty index
Mesowear score
Is diet abrasiveness reflected in the mesowear score?
R2 = 0.66
R2 = 0.35
0
1
2
3
4
5
6
7
0 50 100 150
Faecal silica (mg/kg DM)
Hypsodonty index
Mesowear score
Is diet abrasiveness reflected in the mesowear score?
Is diet abrasiveness reflected in the mesowear score?
R2 = 0.66
R2 = 0.35
0
1
2
3
4
5
6
7
0 50 100 150
Faecal silica (mg/kg DM)
Hypsodonty index
Mesowear score
R2 = 0.40
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.40
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
20 40 60 80 100
%grass
R = 0.38
0
1
2
3
4
0 1 2 3
Habitat category
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty
index
open
medium
closed
This shows that both %grass and habitat influence HI
R2 = 0.40
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.40
R2 = 0.32
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.40
R2 = 0.32
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
R2 = 0.130
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.40
R2 = 0.32
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
R2 = 0.130
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.32
20 40 60 80 100
%grass
R = 0.38
R2 = 0.130
1
2
3
4
0 1 2 3
Habitat category
0
0.5
1
1.5
2
2.5
3
3.5
4
0 20 40 60 80 100
%grass
MesowearScore
open
medium
closed
This shows that the mesowear signal is not catching a habitat effect
R2 = 0.40
R2 = 0.32
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
R2 = 0.130
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.15
0
1
2
3
4
5
6
7
8
9
10
0 50 100 150 200 250
Precipitation (mm)
Hypsodonty index
Mesowear score
R2 = 0.13
0
1
2
3
4
5
6
7
8
9
10
0 500 1000 1500 2000
Evaporation (mm)
Hypsodonty index
Mesowear score
R2 = 0.40
R2 = 0.32
0
1
2
3
4
5
6
7
8
9
10
0 20 40 60 80 100
%grass
Hypsodonty index
Mesowear score
Mesowear score, diet and habitat
R2 = 0.38
R2 = 0.130
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Habitat category
Hypsodonty index
Mesowear score
R2 = 0.15
R2 = 0.050
1
2
3
4
5
6
7
8
9
10
0 50 100 150 200 250
Precipitation (mm)
Hypsodonty index
Mesowear score
R2 = 0.13
R2 = 0.04
0
1
2
3
4
5
6
7
8
9
10
0 500 1000 1500 2000
Evaporation (mm)
Hypsodonty index
Mesowear score
Mesowear score and body mass
R2 = 0.10
0.01
0.1
1
10
1 10 100 1000 10000
Body mass (kg)
Hypsodonty index
Mesowear score
not significant after phylogenetic control
Mesowear score and body mass
R2 = 0.10
R2 = 0.00
0.01
0.1
1
10
1 10 100 1000 10000
Body mass (kg)
Hypsodonty index
Mesowear score
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Mesowear score
Hypsodonty
index
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Mesowear score
Hypsodonty
index
10-100 kg
100-1600 kg
Influence of body mass not significant with phylogenetic control
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Mesowear score
Hypsodonty
index
Ruminants CamelidsEquids RhinosHyraxes
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
0 1 2 3 4
Mesowear score
Hypsodonty
index
Tragulids
Giraffids
Cervids
Bovids
Antilocapra
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
0 1 2 3 4
Mesowear score
Hypsodonty
index
Bovinae AlcelaphinaeAepyceroidae HippotraginaeReduncinae CephalophinaeSaiginae AntilopinaeCaprinae
Does tooth wear drive the evolution of hypsodonty?
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4
Mesowear score
Hypsodonty
index
open
medium
closed
This shows that both mesowear and habitat influence HI - again showing that there is something in habitat that the mesowear score does not catch
Predicting %grass / precipitation
For predicting %grass, in a GLM both HI and MesowearScore are significant; body mass only when not correcting for phylogeny.
LS LogBM HI Mesoscore r2 p p p OLS (F) 8.424 0.005 (F) 16.192
Predicting %grass / precipitation
For predicting %grass, in a GLM both HI and MesowearScore are significant; body mass only when not correcting for phylogeny.
LS LogBM HI Mesoscore r2 p p p OLS (F) 8.424 0.005 (F) 16.192
Predicting %grass / precipitation
For predicting %grass, in a GLM both HI and MesowearScore are significant; body mass only when not correcting for phylogeny.
LS LogBM HI Mesoscore r2 p p p OLS (F) 8.424 0.005 (F) 16.192
Predicting %grass / precipitation
For predicting %grass, in a GLM both HI and MesowearScore are significant; body mass only when not correcting for phylogeny.
LS LogBM HI Mesoscore r2 p p p OLS (F) 8.424 0.005 (F) 16.192
common taxa rare taxa
Crown types Localities
Relationship HI - enamel ridge alignment?
Relationship HI - enamel ridge alignment?
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4 5 6
HI
Fre
quency (
10-4
0°)
Relationship HI - enamel ridge alignment?
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4 5 6
HI
Fre
quency (
10-4
0°)
n.s.
No link between HI and enamel ridge alignment - no realtionship between HI and one quantitative tooth shape parameter we have
Relationship HI - enamel ridge alignment?
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4 5 6
HI
Fre
quency (
10-4
0°)
n.s.
Enamel ridge alignment and hypsodonty are two independent adaptations
Some brachydont teeth do good things ...
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
free-ranging captive
MPS (
mm
)
Przewalski
Tapir
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
free-ranging captive
MPS (
mm
)
Przewalski
Tapir
0
0.2
0.4
0.6
0.8
1
1.2
free-ranging captive
MPS (
mm
)
Aurochs
Giraffe
0
0.2
0.4
0.6
0.8
1
1.2
free-ranging captive
MPS (
mm
)
Aurochs
Giraffe
Silica (%DM)
Summary
•!Hypsodonty can most logically be explained as a adaptation to tooth wear
•!Abrasiveness of diet is mostly a concept and not an empirical measure
•!Differences in wear can be demonstrated under different situations
•!Important differences in the signal of hypsodonty (evolutionary) and mesowear (individual’s lifetime)
•!Quantitative effects of diet on tooth wear are needed
Summary
The mesowear score as in our collection does not relfect climate/habitat to the same extent as HI. HI is an evolutionary signal. MesoScore is a signal from an individual animal that may be exposed to different conditions than the animal was during its evolution of HI.
This does not mean that at lower-scale comparisons (e.g. within one group of herbivores only) the MesoScore is more linked to climate parameters.