Re: [MORPHMET] Ontogenetic changes in morphology
Dear Adeline Yong Right now you are essentially plotting size (of the claw) against size (of the crab). What you are interested in is shape against size. I am not sure what program you are using now, but I would suggest MorphoJ, as it is quite user friendly. You should do a multivariate regression of the Procrustes coordinates onto size.You could then play around with different size measures. (ln) centroid size of the object of interest is commonly used for these types of analyses, but you could also try doing it with carapace size and see if you get different results. I hope that helps. Best wishes, Anneke van Heteren -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
Re: [MORPHMET] Ontogenetic changes in morphology
You can also perform this analysis as a multivariate linear model (using first variable, ln(CS) as independent variable) with PAST. Nervertheless, number of Procrustes versus number of specimens can be a problem if you sample size is not large enough. Pere M. On Dm, Febrer 18, 2015 09:06, Anneke van Heteren wrote: Dear Adeline Yong Right now you are essentially plotting size (of the claw) against size (of the crab). What you are interested in is shape against size. I am not sure what program you are using now, but I would suggest MorphoJ, as it is quite user friendly. You should do a multivariate regression of the Procrustes coordinates onto size.You could then play around with different size measures. (ln) centroid size of the object of interest is commonly used for these types of analyses, but you could also try doing it with carapace size and see if you get different results. I hope that helps. Best wishes, Anneke van Heteren -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org. -- Pere M. Parés-Casanova PhD Part-time Lecturer Dep. of Animal Production School of Agrifood and Forestry Science and Engineering University of Lleida Av. Rovira Roure 191 25198 Lleida (CATALUNYA, Spain) Phone:+34973706460 Fax: +34973702874 _ ( \__ \ ) \ ---¬/ / | Confidentiality Note: This message is intended for use only by the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If you have received this communication in error, please contact the sender immediately and destroy the material in its entirety, whether electronic or hard copy. Kindly note that, E-mail transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted,lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept liability for any errors or omissions in the contents of this message, which arise as a result of e-mail transmission. If verification is required please request a signed hard-copy/scanned version. Thank you, gràcies. -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
[MORPHMET] Ontogenetic changes in morphology
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 -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
Re: [MORPHMET] Ontogenetic changes in morphology
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 adeline.yon...@gmail.com 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 -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org. -- Carmelo Fruciano Marie Curie Fellow - University of Konstanz - Konstanz, Germany Honorary Fellow - University of Catania - Catania, Italy e-mail c.fruci...@unict.it http://www.fruciano.it/research/ -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
