-------- Original Message -------- Subject: Re: MorphoJ visualisations Date: Tue, 16 Feb 2010 13:08:35 -0500 From: Chris Klingenberg <[email protected]> Reply-To: [email protected] Organization: University of Manchester To: [email protected] References: <[email protected]> Dear Tim Thanks for pointing out the weak spot in the MorphoJ documentation. I've just posted a slightly revised version, which will also be packaged with the new version of MorphoJ that's currently in the works (with some extra bits and bobs). The 'secret' of the visualization of shape changes associated with canonical variate (CV) axes is a regression of shape on the respective CV scores, as it was suggested by Rohlf et al. (Rohlf, F.J., Loy, A. & Corti, M. 1996 Morphometric analysis of Old World Talpidae (Mammalia, Insectivora) unsing partial-warp scores. Systematic Biology 45, 344–362). The scale factor for CV shape changes is in units of Mahalanobis distance. This is the shape change per unit of within-group shape variation in that direction; this is the same as the units of the axes of the scatter plots of CV scores (e.g. the default of 10.0 is a change of 10 units in the positive direction along the respective CV axis). I hope this helps. Best wishes, Chris morphmet wrote:
-------- Original Message -------- Subject: MorphoJ visualisations Date: Tue, 16 Feb 2010 11:48:01 -0500 From: Tim tkint <[email protected]> To: <[email protected]> Dear all, I am doing a geometric morphometric study on sexual dimorphism in cichlids. I like using MorphoJ, but I am a little confused about the visualisations. First of all, what exactly does the scale factor mean? Is this value linked to the coordinates of the specimens along the axes: (e.g. scale factor 10 corresponds to shape at score 10 on axis) or is it a multiplication of the total shape change along an axis? And what is the ‘secret’ behind the visualisation of the shape changes along CVA-axes? (Several publications have mentioned that CVA-results are difficult to visualize directly because a CVA re-scales axes using within-group variation.) Kind regards, Tim. ___________________ Tim tkint Ghent University Evolutionary Morphology of Vertebrates K.L. Ledeganckstraat 35, B-9000 Gent, Belgium tel: +32 9 264 52 33 E-mail: [email protected] <mailto:[email protected]> http://www.fun-morph.ugent.be/
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