P.S. I don't know your specific case well enough and obviously it all
relates to the question you're trying to answer. But something that
came to mind if that you might want to consider (if it fits with what
you are testing/showing) plotting PGLS estimates of mean shape for
each of your groups.
Christy Hipsley <[email protected]> ha scritto:
Dear Morphmet-ers,
I'm seeking advice on methods for visualizing shape features that
distinguish multiple groups using GM. I know CVA has fallen out of favor
for a number of reasons discussed here - e.g., more variables than groups,
nonisotropic variation:
Mitteroecker, P., and Bookstein, F. 2011. Linear discrimination,
ordination, and the visualization of selection gradients in modern
morphometrics. Evol. Biol. 38:100–114.
Klingenberg, C. P., and Monteiro, L. R. 2005. Distances and directions in
multidimensional shape spaces: Implications for morphometric applications.
Syst. Biol. 54:678–688.
Although given these limitations, is it really expected to give completely
false results regarding the visualization of shape changes? In my study
sytem, I show that ecological groups have statistically different cranial
shapes, using both Procrustes ANOVA and PGLS. Now I simply want to
visualize what the main features are that distinguish them, preferably
using warps or wireframes, so that those changes must be directly
relateable to the original landmark coordinates. I did that using
individual specimens instead of species means, so I have 161 individuals vs
144 variables (48 landmarks*3D). I also did a between-group PCA on the
species means which shows the same pattern, so is it technically "wrong" to
show both?
Thanks for any feedback on this issue, and I would appreciate to hear any
alternative methods that people might use. I use MorphoJ and Geomorph for
analyses.
Best,
Christy
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Carmelo Fruciano
Postdoctoral Fellow - Queensland University of Technology - Brisbane,
Australia
Honorary Fellow - University of Catania - Catania, Italy
e-mail [email protected]
http://www.fruciano.it/research/
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