Hi all,

I am getting weird results when doing a PLS analysis in MorphoJ.

I have a dataset of 12 minke whale skulls of different ontogenetic ages and I 
wanted to test if the anterior part (rostrum) and posterior part (braincase) 
are modular and how their shape changes relative to one another during growth.
Both parts are blocks of the same configuration and they are on the same 
Procrustes fit, as recommended for these kinds of studies.

I am getting strange results on the block 1 PLS1 vs block 2 PLS1 graph, with 
all the specimens falling on the same "line" (looks like a linear regression 
with a 45' slope), but instead of having the specimens ordered from the 
youngest to the oldest, with youngest close to 0 and oldest at the other end, 
the pattern is strange.
The adults fall around the middle of the distribution, with the youngest 
specimens close to 0 and intermediate specimens at the top of the distribution. 
So it kind of seems that the shapes are "reverting" back in adults compared to 
younger specimens.

Unfortunately I can't attach an image so I tried to describe the problem in the 
best way possible.
Have you ever seen a pattern as the one I described? If not, in your experience 
is it biologically possible or it implies that there is something wrong with my 
I think my limited sample size might be part of the problem, but I'm not sure 
if that's the only reason why I'm seeing this pattern.

Let me know if you need additional info.
Thank you very much!
Agnese Lanzetti

Ph.D. candidate
Joint Doctoral Program in Evolutionary Biology
San Diego State University
University of California, Riverside

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