Comparison of Mandibular Phenotypic and Genetic Integration between Baboon and Mouse

Department of Anthropology, Pennsylvania State University, 409 Carpenter Building, University Park, PA 16802, USA.
Evolutionary Biology (Impact Factor: 2.61). 03/2009; 36(1):19-36. DOI: 10.1007/s11692-009-9056-9
Source: PubMed


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.

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Available from: Joan T. Richtsmeier
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    • "Notice that Total integration correspond to the sum of all five individual hypothesis into one composite hypothesis and the Neuroface corresponds to the conjoint test of late and early developmental influence (or the sum of both individual hypothesis, Face and Neurocranium). With respect to mandibular traits, we considered the distinction between the Alveolar Processes and the Ascending Ramus, according to Fig. 4, as proposed by several authors (e.g.: Cheverud et al. 1997; Klingenberg et al. 2004; Willmore et al. 2009). We also tested a third, composite hypothesis (Total), corresponding to the sum of Alveolar and Ascending hypotheses. "
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    ABSTRACT: Patterns of genetic covariance between characters (represented by the covariance matrix G) play an important role in morphological evolution, since they interact with the evolutionary forces acting over populations. They are also expected to influence the patterns expressed in their phenotypic counterparts (P), because of limits imposed by multiple developmental and functional restrictions on the genotype/phenotype map. We have investigated genetic covariances in the skull and mandible of the vesper mouse (Calomys expulsus) in order to estimate the degree of similarity between genetic and phenotypic covariances and its potential roots on developmental and functional factors shaping those integration patterns. We use a classic ad hoc analysis of morphological integration based on current state of art of developmental/ functional factors during mammalian ontogeny and also applied a novel methodology that makes use of simulated evolutionary responses. We have obtained P and G that are strongly similar, for both skull and mandible; their similarity is achieved through the spatial and temporal organization of developmental and functional interactions, which are consistently recognized as hypothesis of trait associations in both matrices.
    Full-text · Article · Aug 2014 · Evolutionary Biology
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    • "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 2003, 2006; Kim 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. 2008, 2009; Burgio 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 EVOLUTION & DEVELOPMENT XX:XX, 1–12 (2013) DOI: 10.1111/ede.12026 "
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    ABSTRACT: Mammalian tooth and jaw development must be coordinated well enough that these systems continue to function together properly throughout growth, thus optimizing an animal's survival and fitness, as well as a species' success. The persistent question is how teeth and jaws remain developmentally and functionally viable despite sometimes monumental evolutionary changes to tooth and jaw shape and size. Here we used the p63 mouse mutant to test the effect of tooth development - or the lack thereof - on normal mandible developmental morphology. Using 3D geometric morphometrics, we compared for the first time mandible shape among mice with normal tooth and jaw development against p63 double knock-out mice, with failed tooth development but apparently normal jaw development. Mandible shape differed statistically between toothless (p63(-/-) ) and toothed (p63(+/-) , p63(+/+) ) mice as early as embryonic day (E) 18. As expected, most of the shape difference in the p63(-/-) mandibles was due to underdeveloped alveolar bone related to arrested odontogenesis in these E18-aged mice. Mandible shape did not differ statistically between p63(+/-) and p63(+/+) adult mice, which showed normal tooth development. Our results support the idea of a gene regulatory network that is exclusive to the mandible and independent of the dentition. This study also underscores the biomechanical impact of the teeth on the developing alveolar bone. Importantly, this work shows quantitatively that the p63 mutant is an apt model with which to study mandible morphogenesis in isolation of odontogenesis to clarify developmental relationships between the teeth and jaws.
    Full-text · Article · Jul 2013 · Evolution & Development
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    • "adaptations of primates from the great apes [39] [40] [41] [42] to the creation of the " gracile " and " robust " clades of the australopiths [43] [44] [45] [46] [47] [48] [49]. Outside of hominin paleontology, morphological integration of the mandible has been studied in mice [50– 52], baboons [50] and chimpanzees and gorillas [53]. Given the emphasis on cranial form in the evolution of modern humans, and the extensive literature concerning nonhuman mandibular integration, the decreased focus of morphological integration research in hominins involving the mandible is surprising. "
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    ABSTRACT: Craniofacial integration is prevalent in anatomical modernity research. Little investigation has been done on mandibular integration. Integration patterns were quantified in a longitudinal modern human sample of mandibles. This integration pattern is one of modularization between the alveolar and muscle attachment regions, but with age-specific differences. The ascending ramus and nonalveolar portions of the corpus remain integrated throughout ontogeny. The alveolar region is dynamic, becoming modularized according to the needs of the mandible at a particular developmental stage. Early in ontogeny, this modularity reflects the need for space for the developing dentition; later, modularity is more reflective of mastication. The overall pattern of modern human mandibular integration follows the integration pattern seen in other mammals, including chimpanzees. Given the differences in craniofacial integration patterns between humans and chimpanzees, but the similarities in mandibular integration, it is likely that the mandible has played the more passive role in hominin skull evolution.
    Full-text · Article · Apr 2011
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