Page 9 - Asylv_molars_Pmax_revised_2014_01

9

towards
Mediterranean
regions
(Fig.
3B).
In
few
cases,
insular
populations
tended
to
display
larger

molars
than
their
mainland
relatives,
especially
in
Porquerolles.
The
trend
observed
in
the
islands
of

Yeu,
Elba
and
Marettimo
has
to
be
taken
with
caution
since
these
islands
were
sampled
by
a
single

specimen
each.

Stability
of
Pmax
among
populations

The
robust
estimation
of
Pmax
requires
well-­‐sampled
populations
(Polly
2005;
Renaud
and
Auffray

2013).
Pmax
was
thus
evaluated
in
populations
documented
by
more
than
30
specimens
(Table
1).

Tourch,
Mimizan,
Lantabat
and
Tarquinia
documented
mainland
populations,
with
two
different

phylogenetic
lineages
represented
(Western
Europe
and
Italy).
Porquerolles
further
documented
an

insular
situation.

Pmax
was
robustly
estimated
in
all
populations
and
highly
correlated
among
them
(Table
3;
Fig.
4).

The
correlation
was
especially
high
(R
>
0.9)
between
all
mainland
Pmax.
Pmax
in
Porquerolles
was

less
strongly
correlated
to
mainland
directions
(0.7
<
R
<
0.9).
Pmax
corresponds
to
a
trend
ranging

from
stocky,
broad
molars
to
elongated,
slender
ones
(Fig.
2B).

Pmax
and
evolutionary
directions
on
mainland

The
role
of
Pmax
as
possible
channel
to
evolution
was
investigated
by
comparing
Pmax
to
various

evolutionary
directions.
The
overall
direction
of
evolution
on
mainland
was
estimated
as
the
first
axis

of
the
inter-­‐group
VCV
(V1mainland;
30.6%
of
the
variance).
This
direction,
summarizing
all
other

directions
of
variation,
was
sensitive
to
sampling.
This
may
be
due
to
the
fact
that
it
relies
on
a

limited
numbers
of
group
means
(N
=
33).
Furthermore,
the
limited
amount
of
variance
explained
by

this
first
axis
lets
much
of
variance
on
subsequent
axes,
and
the
first
eigenvectors
may
be
permuted

in
some
bootstrapped
samples.

Nevertheless,
this
direction
was
congruent
with
Pmax
of
most

populations
(Table
4;
Fig.
4).

The
directions
of
evolution
between
mainland
biogeographic
groups
(Western
European
vs.
Italian

lineages,
and
within
the
Western
European
lineage,
Western
France
vs.
continental
populations
at

the
same
latitude)
were
further
compared
to
Pmax
(Table
4).
These
directions
were
not
parallel
to

Pmax.