-------- Original Message --------
Subject: Re: Analyzing ontogenetic trajectory angles
Date: Wed, 20 Jul 2011 16:22:42 -0400
From: [email protected]
To: [email protected]
CC: morphmet <[email protected]>
Dear all,
ontogeny pakage (under development by Piras and
Ferrara) is not yet released.
WE just completed some functions. ONE OF THESE (AMONG
OTHERS) is the ontogenetic convergence test.
Note that it is SLIGhTLY DIFFERENT form its previous
published applications. Further details can be
furnished to anyone intersted in. In any case all this
was inspired by Dean Adams past papers- cited in
Dean's previous post - and Piras et al (2010) paper.
Actually, we are working for a complete set of
functions (some are new concepts
actually....)developed to investigate from all points
of view ontogenetic trajectories when two or more
groups are under study in order to assess PAIRWISE
their differences(multivariate elevation, multivariate
slope, multivariate disparity around trajectory, the
course of multivariate heteroskedasticity, etc.). All
p-values are assessed by means of permutations on
group membership.
These methods are presented in a paper that is under
review now.
I had in mind to annouce in morphmet the completion of
our effort but we dont finished yet.......
Contact me ([email protected]) if you are interested in
best
paolo
Dear David,
I am interesting in the R Package Ontogeny,
Best
Víctor
2011/7/20 morphmet
<[email protected]
<mailto:[email protected]>>
-------- Original Message --------
Subject: Re: Analyzing ontogenetic trajectory
angles
Date: Tue, 19 Jul 2011 13:42:00 -0400
From: [email protected]
<mailto:[email protected]>
To: [email protected]
<mailto:[email protected]>
Dear David,
Im writing a R package (named "ontogeny") with a
colleague (Giancarlo Ferrara) containing
functions
used in
Paolo Piras, Paolo Colangelo, Dean C Adams,
Angela
Buscalioni, Jorge Cubo, Tassos Kotsakis, Carlo
Meloro
and Pasquale Raia. 2010. The Gavialis-Tomistoma
debate: the contribution of skull ontogenetic
allometry and growth trajectories to the study of
crocodylian relationships.Evolution and
Development
12(6):568-79
These new functions are newely developed
functions
(albeit inspired by Dean Adams past papers and
Piras
et al 2010)
You are refrerring in your post to the
ontogenetic
convergence test of our paper. This can be
applied to
any linear model (not only, of course, to
ontogenetic
data)
Let me know if you (or everyone else) need the
function code. I cand send it to you.
-------- Original Message --------
Subject: Analyzing ontogenetic trajectory
angles
Date: Mon, 18 Jul 2011 14:46:19 -0400
From: David Katz <[email protected]
<mailto:[email protected]>>
To: [email protected]
<mailto:[email protected]>
Hello,
I have read several morphometrics papers which
test
for significant
differences in ontogenetic trajectory between two
groups (species,
subspecies, etc) by calculating the "angle"
between
their growth
trajectories. However, parts of (or even lots
of) the
method remain
unclear to me.
First, it seems that calculation of the angle
requires
calculation of
two simple regression lines, one for each group,
with
the angle being
the arc subtended by the two lines. One axis for
these regression
plots/calculations is the distribution of
specimens
along a PC which is
significantly correlated with size or age
(usually the
first PC). But
it is not clear to me what the second axis is.
Log
centroid size?
Second, the significance of the angle is tested
by
randomly permuting
specimens between the two groups 1000 or more
times,
then calculating a
new angle for each permutation. Significance is
then
tested against the
distribution of permutation-generated angles.
But
what is the
permutation procedure? Do we only permute a
single
specimen each time?
Third, if I'm understanding the method correctly,
then
absent an
additional scaling step, the two lines from which
the
angle is
calculated are not likely to be of the same
length.
How is this
accounted for, if at all?
Any help, or a reference to a good, explicit
journal
or book
explanation, would be very much appreciated.
Thanks.
David Katz
Doctoral Candidate
Department of Anthropology--Evolutionary Wing
University of California, Davis
Young Hall 204
/--Trying to focus on one distraction at a
time/--
--
Victor Hugo Cruz Escalona
Instituto Politécnico Nacional
Centro Interdisciplinario de Ciencias Marinas
Departamento de Pesquerías y Biología Marina
Laboratorio de Pinnípedos
Aparatado Postal 592, La Paz, Baja California Sur
CP 23096, México
Teléfono: 01 612 12 253 66
[email protected] <mailto:[email protected]>
