Page 6 - Renaud_Michaux_2007

S. Renaud and J. R. Michaux

(a) Mandible (EFT7) (b) Molar M1 (RFT9)
3 3
SIC-M
FR-PTCR
FR-IEV
FR-PORQ
2 2 SIC-GRAT
IT-TARQ SIC-FIC
MdCA2 (16.3%) 1 PYR FR-S FR-OL FR-NM M1CA2 (20.1%) 1 0 FR-PTCR IT-CAL IT-GROS FR-IEV
SP-N
FR-LA
CO
FR-CH
SP-N
FR-MTP
FR-PORQ
ELBA
0
FR-MTP
IT-GROS
IT-CAL
SP-ALC
FR-Y IBIZ SP-MUR SIC-M IBIZ FR-S FR-LA
FR-RE SP-MUR FR-Y
ELBA SP-ALC FR-RE
–1 SIC-FIC IT-TARQ –1 PYR FR-CH
SARD
CO SIC-GRAT
SARD FR-OL
FR-NM
–2 –2
–4 –3 –2 –1 0 1 2 3 4 –3 –2 –1 0 1 2 3
MdCA1 (19.0%) M1CA1 (24.0%)

cor.
cond.
ang.

Figure 2 Shape variability of the mandible (a) and first upper molar (b), estimated by the first two axes of a canonical analysis on the EFT
Fourier coefficients of the mandible and the RFT coefficients of the M1 outline. Symbols correspond to the average value per geographical
group. Dotted lines enclose the range of variation of the mainland western European and Italo-Balkanic clades. Reconstructed outlines on
the plot visualize the average shape of some geographical groups (EFT mandible, seven harmonics, RFT M1, nine harmonics). Below, shape
changes corresponding to the canonical axes are depicted. The open outline corresponds to the average shape; light grey outlines to the
maximum values of the axes on the plot; dark grey outlines to exaggerated variations on the axes (mandible: scores ¼ 10/–10 and M1:
scores ¼ 5/–5). On the lowermost upper mandible outline, abbreviations indicate the name of the processes: cor., coronoid; cond., condylar;
ang., angular.

segregated without overlap on axes CA1 and CA2. Except for posterior labial cusp are shifted to the negative side. The
Corsica and the single M1 from Yeu, insular morphologies second axis opposes slender (positive CA2) to massive molars
scatter outside the mainland range. Sicilian populations (that (negative CA2).
constitute a peculiar genetic clade related to the Italian one)
are grouped towards positive CA2 values but still remain close
Interplay of the latitudinal gradient with insular
to the Italian group. These two genetically related clusters are
divergence
further differentiated along axis CA3 (11.9%, data not shown).
Other insular populations are displaced towards negative CA1 A primary way of investigating the influence of geography on
values. The most divergent M1 samples on the first two morphological differentiation is to plot the results of the
canonical axes are Porquerolles and Port-Cros (along CA1), canonical analyses as a function of latitude (Fig. 3a,c). Since
the single tooth from Marettimo (towards positive CA2), insular effects might interfere with the latitudinal gradient, the
Noirmoutier and Ole ´ron (towards negative CA2). existence of a linear relationship between the canonical axes
Reconstructed outlines indicate that molars with a straight and latitude was tested on mainland samples only. The
labial side (on the left of the outline) and a pointed fore and gradient appeared to be expressed on axis CA2 for mandibles
back part are displaced on the positive side of the first axis, (linear correlation of group means with latitude, N ¼ 12, CA1:
whereas molars with an undulating labial side and a prominent R ¼ 0.190, P ¼ 0.553; CA2: R ¼ 0.788, P ¼ 0.002) and on

344 Journal of Biogeography 34, 339–355
ª 2006 The Authors. Journal compilation ª 2006 Blackwell Publishing Ltd