Error starting packages "rgl" and "geomorph" on R on Mac

Question

I am trying to run the "geomorph" package on R. I know that I need to install the "rgl" and "geomorph" packages and the following (respectively) for this:

install.packages("rgl") 

Then I:

 require("rgl") 

But for both, the following error occurred:

 > require("rgl") Loading required package: rgl Error : .onLoad failed in loadNamespace() for 'rgl', details: call: dyn.load(file, DLLpath = DLLpath, ...) error: unable to load shared object '/Library/Frameworks/R.framework/Versions/3.1/Resources/library/rgl/libs/rgl.so': dlopen(/Library/Frameworks/R.framework/Versions/3.1/Resources/library/rgl/libs/rgl.so, 6): Library not loaded: /opt/X11/lib/libGLU.1.dylib Referenced from: /Library/Frameworks/R.framework/Versions/3.1/Resources/library/rgl/libs/rgl.so Reason: image not found 

Please, help. Maybe I'm running R on OS X Yosemite? I read that in Yosemite there is an error or function that causes errors for R users.