Principal component analysis of reduced data sets, scatter plots. a S. amabilis and S. opacus b S. opacus and S. parvulus c populations of S. mayri d S. maravalhas and S. scrobifer e populations of striate-mandibled S. amabilis vs. smooth-mandibled (SM) S. amabilis f populations of S. opacus g populations of typical S. bondari vs. reduced-hair (RH) S. bondari h populations striate-mandibled S. saussurei vs. smooth-mandibled (SM) S. saussurei.