Thank you for the answers received so far. F. James Rohlf, my populations are predefined by country of origin. They just reappear in the PCA. So I think I can exclude size or age classes.
> Date: Thu, 8 Nov 2007 17:22:42 +0100 > From: [EMAIL PROTECTED] > To: [email protected] > Subject: RE: PCA clusters > > Are the apparent populations defined in advance or only suggested by the > patterns you see after looking at the data? If predefined then there are > methods. If they are only suggested by the data then real testing is > difficult. Because the differences are only along PC1 one wonders > whether these may just be size classes corresponding to age classes - or > do they correspond to different geographic regions? > > ------------------------ > F. James Rohlf, Distinguished Professor > Ecology & Evolution, Stony Brook University > www: http://life.bio.sunysb.edu/ee/rohlf > > > > -----Original Message----- > > From: morphmet [mailto:[EMAIL PROTECTED] > > Sent: Thursday, November 08, 2007 7:17 AM > > To: morphmet > > Subject: PCA clusters > > > > Dear morphometricians, > > > > I have the following problem: > > > > I have performed a PCA of shape (relative warps analysis) on a set of > > mouse mandibles from animals of different geographic origins. Now in a > > plot of PC1 vs PC2, I can "see" that PC1 sorts specimens into broadly > > overlapping clusters corresponding to the respective origins of the > > mice, while PC2 (and the other PCs) do not. The problem is now that the > > overlaps of the "population" clusters are rather broad so the question > > is how different they actually are. Also, I have several "populations", > > so it looks like a continuum of overlapping clouds. > > Could you recommend a means to quantify and/or somehow test the actual > > differences between "populations" along PC1? > > > > Louis Boell > > > > ----------------------------------------------------------------------- > > - > > Machen Sie Ihre E-Mail-Kontakte zu Messenger-Freunden! Einfacher > > Adressimport! > > <http://redirect.gimas.net/?cat=hmtl&n=M1007AI&d=http://messenger.live. > > de/ersteschritte_adressimport.html> > > > > -- > > Replies will be sent to the list. > > For more information visit http://www.morphometrics.org > > > > > -- > Replies will be sent to the list. > For more information visit http://www.morphometrics.org > ------------------------------------------------------------------------ Jetzt mit 2 GB Speicherplatz: Noch mehr Möglichkeiten! Das neue Hotmail ist da! <http://redirect.gimas.net/?cat=hmtl&n=M1007HM&d=http://get.live.com/mail/overview> -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
