Article

A preliminary analysis of correlations between chewing motor patterns and mandibular morphology across mammals.

Department of Anatomy and Neurobiology, Northeastern Ohio Universities Colleges of Medicine, Rootstown, OH 44272, USA.
Integrative and Comparative Biology (impact factor: 2.45). 06/2011; 51(2):260-70. DOI:10.1093/icb/icr066
Source: PubMed

ABSTRACT The establishment of a publicly-accessible repository of physiological data on feeding in mammals, the Feeding Experiments End-user Database (FEED), along with improvements in reconstruction of mammalian phylogeny, significantly improves our ability to address long-standing questions about the evolution of mammalian feeding. In this study, we use comparative phylogenetic methods to examine correlations between jaw robusticity and both the relative recruitment and the relative time of peak activity for the superficial masseter, deep masseter, and temporalis muscles across 19 mammalian species from six orders. We find little evidence for a relationship between jaw robusticity and electromyographic (EMG) activity for either the superficial masseter or temporalis muscles across mammals. We hypothesize that future analyses may identify significant associations between these physiological and morphological variables within subgroups of mammals that share similar diets, feeding behaviors, and/or phylogenetic histories. Alternatively, the relative peak recruitment and timing of the balancing-side (i.e., non-chewing-side) deep masseter muscle (BDM) is significantly negatively correlated with the relative area of the mandibular symphysis across our mammalian sample. This relationship exists despite BDM activity being associated with different loading regimes in the symphyses of primates compared to ungulates, suggesting a basic association between magnitude of symphyseal loads and symphyseal area among these mammals. Because our sample primarily represents mammals that use significant transverse movements during chewing, future research should address whether the correlations between BDM activity and symphyseal morphology characterize all mammals or should be restricted to this "transverse chewing" group. Finally, the significant correlations observed in this study suggest that physiological parameters are an integrated and evolving component of feeding across mammals.

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Keywords

19 mammalian species
 
address long-standing questions
 
basic association
 
BDM activity
 
different loading regimes
 
evolving component
 
Feeding Experiments End-user Database
 
jaw robusticity
 
mammalian phylogeny
 
mammalian sample
 
morphological variables
 
physiological parameters
 
relative area
 
relative peak recruitment
 
relative recruitment
 
share similar diets
 
significant associations
 
symphyseal area
 
transverse chewing
 
use significant transverse movements