Discerning evolutionary processes in patterns of tamarin (genus Saguinus) craniofacial variation
Article first published online: 7 FEB 2002
Copyright © 2002 Wiley-Liss, Inc.
American Journal of Physical Anthropology
Volume 117, Issue 3, pages 260–271, March 2002
How to Cite
Rogers Ackermann, R. and Cheverud, J. M. (2002), Discerning evolutionary processes in patterns of tamarin (genus Saguinus) craniofacial variation. Am. J. Phys. Anthropol., 117: 260–271. doi: 10.1002/ajpa.10038
- Issue published online: 7 FEB 2002
- Article first published online: 7 FEB 2002
- Manuscript Accepted: 8 OCT 2001
- Manuscript Received: 12 MAY 2000
- NSF. Grant Number: SBR-9632163
- cranial morphology;
- quantitative methods;
- genetic drift
Quantitative genetic theory specifies evolutionary expectations for morphological diversification by genetic drift in a monophyletic clade. If genetic drift is responsible for the evolutionary morphological diversification of a clade, patterns of within- and between-taxon morphological variance/covariance should be proportional. We tested for proportionality of within- and between-species craniofacial morphological variation in 12 species of tamarins (genus Saguinus). We found that within- and between-taxon morphological variations across the entire genus were not proportional, and hence not likely to be due to genetic drift alone. The primary deviation from proportionality is that size and size-related shape in the cranium is more variable relative to other aspects of cranial morphology than expected under genetic drift, suggesting differential size selection between the two major clades, the small-bodied and large-bodied tamarins. Within each of these major clades, most of the interspecific variation is consistent with the pattern expected under genetic drift, although specific contrasts may indicate the involvement of differential selection. Morphological distances among taxa do not correspond very closely to the phylogeny derived from mtDNA. In particular, S. oedipus and S. geoffroyi are very distinct morphologically from the rest of the tamarins, although they are phylogenetically the sister clade to a clade containing S. midas and S. bicolor. Morphological similarity is not a good guide to phylogenetic affinity in the tamarins, especially with regard to deeper nodes in the phylogenetic tree. Am J Phys Anthropol 117:260–271, 2002. © 2002 Wiley-Liss, Inc.