-------- Original Message --------
Subject: RE: Describe shape in fish
Date: Thu, 20 Nov 2008 00:13:38 -0800 (PST)
From: Louis Boell <[EMAIL PROTECTED]>
To: <[email protected]>
References: <[EMAIL PROTECTED]>
Hi Cecile,
you could use CVA (canonical variates analysis) to compare shape between
groups. In the case of two groups, there will be one resulting vector of
shape difference between the two groups. Using programs such as IMP or
MorphoJ you can display this vector as "arrows on landmarks" or as a
deformation grid, and thus visualize and describe the shape difference.
For identification of the major axes of shape variation within groups,
PCA (Relative warps analysis) is a suitable technique, which will also
yield deformation grids in IMP, MorphoJ or tpsrelw, for instance.
You can find accessible information on how apply these techniques, what
they are and how to interpret the outcomes in the book
Zelditch et al., 2004
<http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7GW4-4P9K96D-1&_user=43215&_coverDate=11%2F09%2F2007&_rdoc=1&_fmt=full&_orig=search&_cdi=20448&_sort=d&_docanchor=&view=c&_acct=C000003118&_version=1&_urlVersion=0&_userid=43215&md5=22384c051fdc9e5ac82f891e3e67892b#bbib77>
M.L. Zelditch, D.L. Swiderski, H.D. Sheets and W.L. Fink, Geometric
Morphometrics for Biologists: a Primer, Elsevier Academic Press, London
(2004).
Cheers,
Louis
Louis Boell
MPI für Evolutionsbiologie
August-Thienemannstr.2
24306 Plön
[EMAIL PROTECTED]
[EMAIL PROTECTED]
> Date: Thu, 20 Nov 2008 01:22:57 -0500
> From: [EMAIL PROTECTED]
> To: [email protected]
> Subject: Describe shape in fish
>
>
>
> -------- Original Message --------
> Subject: Describe shape in fish
> Date: Wed, 19 Nov 2008 17:05:27 -0800 (PST)
> From: Cécile CROQ <[EMAIL PROTECTED]>
> To: <[email protected]>
>
>
>
> Dear Morphometricians,
>
> I'm working on triplefin fishes, and i'm looking at variations in shape
> within and among different populations of North of New Zealand.
> I used TpsDig to get Bookstein Coordinates for each fish, and TwoGroup
> to compare them.
> I'm now a bit lost on what i should use to evaluate how it is different
> and where that difference lays. For example, is the difference between
> two populations that on got a bigger mouth and smaller tail while the
> other got a smaller mouth and a bigger tail?
> I'm still new to morphometric and i'm not sure which analysis would be
> best, regression or PCA etc.
> Thanks for your help,
>
> Cheers
> Cécile
>
>
> Cécile Croq
> MSc student
> Leigh Marine Laboratory
> P.O. Box 349, Warkworth
> New Zealand
> +64 9 422 6111 Ext. 83627
> Cell phone: 021 156 4491
> email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
>
>
>
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