-------- Original Message --------
Subject: RE: variance in shape
Date: Mon, 2 Jun 2008 07:14:03 -0700 (PDT)
From: F. James Rohlf <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Organization: Stony Brook University
To: [email protected]
References: <[EMAIL PROTECTED]>
Doing that does not really measure the amount of variance. It is a
measure of variance among relative to variance within the a priori
defined groups.
It would be better to first perform a GPA of all specimens at once so as
to project them all into a common tangent space. You can then use
standard methods to compare variation in the two groups (e.g., compare
determinants, trace, or largest root of their covariance matrices).
------------------------
F. James Rohlf, Distinguished Professor
Ecology & Evolution, Stony Brook University
www: http://life.bio.sunysb.edu/ee/rohlf
-----Original Message-----
From: morphmet [mailto:[EMAIL PROTECTED]
Sent: Monday, June 02, 2008 8:59 AM
To: morphmet
Subject: variance in shape
-------- Original Message --------
Subject: variance in shape
Date: Sun, 1 Jun 2008 16:41:20 -0700 (PDT)
From: Chris Harrod <[EMAIL PROTECTED]>
To: [email protected] <[email protected]>
Dear all out there in morpholand.
I want to examine variance in shape between fish found in allopatry and
those found in sympatry with a putative competitor.
Can I simply compare the variance in DF/CVA scores (based on the normal
landmark analyses) between different populations, or am I being
horribly
simplistic?
thanks in advance
Chris
><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><>
Dr Chris Harrod
Lecturer in Fish and Aquatic Ecology
Ecology and Evolutionary Biology
Queen's University Belfast
School of Biological Sciences
Medical Biology Centre
97 Lisburn Road
Belfast BT9 7BL
UK
[EMAIL PROTECTED]
Tel: +44 (0) 28 90972271
Mob: +44 (0) 79 77419314
Fax: +44 (0) 28 90975877
http://www.qub.ac.uk/schools/SchoolofBiologicalSciences/Staff/DrCHarrod
/
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