Comparison of Mandibular Phenotypic and Genetic Integration between Baboon and Mouse

Abstract

In this study we compare patterns of mandibular integration between mice and baboons using both phenotypic and quantitative genetic data. Specifically, we test how well each species fits with the mosaic model of mandibular integration suggested by Atchley and Hall (Biol Rev Camb Philos Soc 66:101–157, 1991) based on developmental modules. We hypothesize that patterns of integration will be similar for mice and baboons and that both species will show strong integration within developmental modules and weaker integration between modules. Corresponding landmark data were collected from the hemi-mandibles of an advanced intercross mouse sample (N = 1239) and mandibles from a baboon sample of known pedigree from the Southwest Foundation for Biomedical Research (N = 430). We used four methods of analysis to quantify and compare the degree of mandibular integration between species including two methods based on a priori assumptions, and two a posteriori analyses. We found that patterns of integration are broadly similar for baboon and mouse mandibles, with both species displaying a modular pattern of integration. While there is a general trend of similarity in integration patterns between species, there were some marked differences. Mice are strongly correlated among distances within the coronoid process and the incisive alveolar region, whereas baboons are strongly integrated within the condylar process. We discuss the potential evolutionary implications of the similar patterns of integration between these species with an emphasis on the role of modularity.

Adaptive Radiations, Ecological Specialization, and the Evolutionary Integration of Complex Morphological Structures

“…Patterns of intraspecific morphological integration in mammal skulls have been found to be considerably stable over large phylogenetic scales (Porto et al 2009). The mandible has also been shown to present similar integration patterns with phenotypic and genetic data for mice and baboons (Willmore et al 2009). The integration patterns in both species were found to generally agree with the Atchley and Hall (1991) developmental model (Willmore et al 2009).…”

“…The mandible has also been shown to present similar integration patterns with phenotypic and genetic data for mice and baboons (Willmore et al 2009). The integration patterns in both species were found to generally agree with the Atchley and Hall (1991) developmental model (Willmore et al 2009). Therefore, we consider that the theoretical integration matrices based on development are an appropriate standard for the expected pattern of developmental integration.…”

“…The general congruence of within-species integration with the expected developmental patterns suggest that, even if there are significant differences among species within dietary groups (which were not tested in the present study), a common pattern emerges from the averaged within-species integration matrices. The pattern differences among dietary groups, on the other hand, should be interpreted cautiously, for they might be explained by functional differences (Willmore et al 2009), or by the instability of integration patterns generated by the differences among species within the dietary groups. Further research with increased sample sizes will allow for a detailed examination of possible causal factors behind the similarities and differences of within-species integration patterns in different ecological contexts.…”

Jaw growth in the absence of teeth: the developmental morphology of edentulous mandibles using the p63 mouse mutant

“…At this time, mouse is probably the longest standing if not also the best-established experimental model available to study mammalian odontogenesis (e.g., Thesleff et al 1987;Vainio et al 1993;Chen et al 1996;Peterková et al 1996;Vaahtokari et al 1996;Chai et al 1998;Cobourne and Sharpe 2002;Thesleff 2003Thesleff , 2006Kim et al 2012) as well as mandible morphogenesis and growth (e.g., Cheverud et al 1991;Leamy 1993;Klingenberg et al 2004;Caumul and Polly 2005;Zelditch et al 2008Zelditch et al , 2009Burgio et al 2012;Renaud et al 2012;Siahsarvie et al 2012), even as it translates to primates (Willmore et al 2009). In particular, the p63 knock-out mouse mutant (Mills et al 1999;Yang et al 1999) has already been applied successfully to study the processes regulating the earliest onset of tooth initiation and morphogenesis (Laurikkala et al 2006;Rufini et al 2006).…”

Morphological Integration of the Modern Human Mandible during Ontogeny

“…It is possible that the increasing modularization seen in the edges involving anterior mandibular height is caused by a similar separation of the anterior and posterior portions of the human mandible (a similar anterior-posterior dichotomy is seen in baboon mandibles [50]).…”