Phenotypic covariance structure in tamarins (genus Saguinus): A comparisonof variation patterns using matrix correlation and common principal component analysis

Constancy of variation/covariation structure among populations is frequentl y assumed in order to measure the differential selective forces which have caused population differentiation through evolutionary time. Following Step pan ([1997] Evolution 51:571-594), this assumption is examined among closel y related tamarin species (genus Saguinus), using two distinct approaches a pplied to the task of evaluating similarity in patterns of morphological va riation: common principal component analysis and matrix correlations. While the results of these analyses may appear contradictory, closer examination reveals them as complementary, highlighting the wisdom of combined methodo logies. Overall, the results reveal a close relationship among the morpholo gically based variance structures of the tamarin species a relationship who se pattern is consistent with the pattern of phylogenetic relatedness as fo und via a molecular genetic study. More specifically, both methodological a pproaches provide some support for divergence of S. geoffroyi and S. oedipu s (with regards to their patterns of morphological variation) from other ta marin species. This suggests that variance/covariance structure may have di verged through evolutionary time in the tamarin lineage, placing assumption s of constancy in doubt. (C) 2000 Wiley-Liss, Inc.