Dr. Cheverud will measure patterns of heritable variation and covariation in the size and shape of the face in two tamarin species, the saddle-back tamarin (Saguinus fuscicollis) and the endangered cotton-top tamarin (S.oedipus), to determine the relative stability of inheritance patterns across these closely related species and the extent to which interspecific differences in facial size and shape are consistent with the inherited pattern. These results will be important in evaluating the genetic basis for evolutionary change in tamarins generally, and also specifically in the endangered cotton-top tamarin. Dr. Cheverud will also examine the extent to which the pattern of facial character inheritance and co-inheritance is consistent with patterns of facial growth. Do characters which are under the influence of the same growth factors tend to be inherited together? In this study, concepts from quantitative genetics and systematics are fused to form the groundwork for future studies in which it may be possible to reconstruct the selective forces responsible for facial size and shape evolution in tamarins. The study populations consist of skeletons obtained over the past 15 years through normal attrition from the Oak Ridge Associated Universities" (ORAU) Marmoset Research Center. Detailed demographic records, including age-at-death and genealogical relationship are available for these specimens providing a rare opportunity for genetic studies on primates. The three-dimensional coordinates of facial landmarks will be recorded and used in a finite-element scaling analysis of facial size and shape. The numerical results of this analysis will be used in a quantitative genetic study of inheritance and co- inheritance of facial features. Patterns of heritable variation will be compared between species and to growth relations using randomization statistical procedures. This study will be unique in bringing together new techniques and concepts in quantitative genetics, morphometrics, and statistics for the study of evolutionary systematics.
