Hi Adeline,
I'm not sure if this helps with your problems, but what you are
describing reminds me of two things:
- MANCOVA using shape variables as dependent, species as categorical
predictor and size (either of the claw or of the body) as covariate
and testing not only for the main effects but also for the interaction
between species and size
- So called "relative warps in size-shape space" (Mitteroecker et al
2004 - J Hum Evol), which I personally used on some fish (Fruciano et
al 2012 - Env Biol Fish), and can be used in your case as an
exploratory tool to "see" if and where there is an "abrupt" change in
the trajectory of each species
I am not sure how plotting claw size on body size would help you with
shape, although maybe that's useful to find how much different
descriptors of size are consistent with each other.
I hope this helps.
Best,
Carmelo
Adeline Yong <[email protected]> ha scritto:
Hi Everyone,
I am exploring the use of GMM to study the ontogenetic changes of claw
morphology in one species of crabs. The tips of the crab claws changes in
curvature (shape) as they grow and there are distinct differences if I
compare the claws of the juvenile crabs and the adults. However, the
intermediate stages are not so obvious. Crabs of various sizes (age) were
collected from two populations and I would like to determine the size when
the change in tip curvature most likely starts for each population. All the
major claws of each crab were photographed and landmarks were placed at the
homologous points of the claws. Semi-landmarks were used for the claw tips
as there were no homologous points along the curvature. ln centrold size
of each individual claw was computed and plotted against body size
(carapace width) of the crabs. I am not sure if I am approaching this the
correct way. Any help would be appreciated.
Thanks in advance.
Adeline
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Carmelo Fruciano
Marie Curie Fellow - University of Konstanz - Konstanz, Germany
Honorary Fellow - University of Catania - Catania, Italy
e-mail [email protected]
http://www.fruciano.it/research/
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