Captive breeding populations of animals have proven extremely valuable to many areas of scientific research. Their value is primarily attributable to the fact that the researcher can control, limit or, at least, identify and measure reliably the environmental and biological factors that might influence variation in the traits or processes of interest. Given this attribute, animals from captive breeding populations have served as research models for wild populations of their own species and, in many well-known instances, for humans as well. In either of these two cases, the validity of any captive animal model is a function of the similarity between it and the modeled species.
Captive baboons have been used extensively in anthropological research as model organisms for studies related to dental development, variation, disease, and evolution in humans and other primate species (1
). Although the utility of captive baboons in these sorts of studies seems entirely justifiable given their phylogenetic proximity and consequent genetic, anatomic, and physiological similarities to higher primate species, it is incumbent upon the researcher to demonstrate comparability between model and modeled species with respect to each phenomenon of interest (i.e., trait, process, etc.) prior to extrapolation of results. Equally important is ascertaining that captive populations are representative of natural or wild types of their species and not a subpopulation with aberrant traits or phenotypic values (i.e., it is difficult to posit that a captive population is a model for other species if it is not adequately representative of non-captive populations of its own).
We are engaged in studies of the genetics of primate dental variation and evolution using data from captive baboons. Given the highly conserved nature of gene regulatory systems across widely diverse mammalian groups (4
), the strong genetic similarity between higher primate species -- 92–95% genetic sequence homology between baboons and humans (3
), the genetic similarities between phylogenetically distant taxa such as humans and mice (5
), and evidence for similar patterns of skeletal morphological integration between closely related primate taxa (6
), we began these studies not expecting significant differences in basic dental biology between wild and captive populations of the same species that have only been isolated for 1–5 generations. Yet, research of dental eruption times in baboons (9
), for example, shows that this is not always true. Although there is considerable similarity in the timing of dental eruption and emergence across wild populations, these processes occur 1.5 years earlier in captive animals (15
). Such observations motivate our view that, when possible, assessment of the degree of similarity between captive and wild populations with respect to a trait of interest is an important and prudent step in research using model organisms.
Here we report on a comparison of dental variation in a colony of captive, pedigreed, breeding baboons housed at the Southwest National Primate Research Center (SNPRC) to that seen in a wild baboon population from Kenya. Although the amount of variation in each population may not be equal, we hypothesized that this variation results from the same biological process in captive and wild populations of the same species. If true, the structure of the variance revealed through principle components analyses should be the same for both populations.