TY - JOUR
T1 - Ontogenetic and functional modularity in the rodent mandible
AU - Menegaz, Rachel A.
AU - Ravosa, Matthew J.
N1 - Funding Information:
We thank Scott Maddux for advice on data analysis, and Beth Brainerd, Jason Organ, David Polly and an anonymous reviewer for helpful comments. Chris Vinyard kindly performed the analyses of food material properties. We greatly appreciate the support of the Biomolecular Imaging Center at the Harry S. Truman VA Hospital. Lastly, we thank Olga Panagiotopoulou and José (Pepe) Iriarte-Diaz for the invitation to contribute to this special issue on “Determinants of mammalian feeding system design”. Funding was provided by the NSF to R.A.M. and M.J.R. ( BCS-1061368 ), and the Wenner-Gren Foundation and the American Society of Mammalogists to R.A.M. Support to R.A.M. was provided by the NSF GRFP , the MU Life Sciences Fellowship Program , and the Bushnell Graduate Education and Research Fund .
Funding Information:
We thank Scott Maddux for advice on data analysis, and Beth Brainerd, Jason Organ, David Polly and an anonymous reviewer for helpful comments. Chris Vinyard kindly performed the analyses of food material properties. We greatly appreciate the support of the Biomolecular Imaging Center at the Harry S. Truman VA Hospital. Lastly, we thank Olga Panagiotopoulou and José (Pepe) Iriarte-Diaz for the invitation to contribute to this special issue on “Determinants of mammalian feeding system design”. Funding was provided by the NSF to R.A.M. and M.J.R. (BCS-1061368), and the Wenner-Gren Foundation and the American Society of Mammalogists to R.A.M. Support to R.A.M. was provided by the NSF GRFP, the MU Life Sciences Fellowship Program, and the Bushnell Graduate Education and Research Fund.
Publisher Copyright:
© 2017 Elsevier GmbH
PY - 2017/10
Y1 - 2017/10
N2 - The material properties of diets consumed by juvenile individuals are known to affect adult morphological outcomes. However, much of the current experimental knowledge regarding dietary effects on masticatory form is derived from studies in which individuals are fed a non-variable diet for the duration of their postweaning growth period. Thus, it remains unclear how intra-individual variation in diet, due to ontogenetic variation in feeding behaviors or seasonal resource fluctuations, affects the resulting adult morphology. Furthermore, the mandible is composed of multiple developmental and functional subunits, and the extent to which growth and plasticity among these modules is correlated may be misestimated by studies that examine non-variable masticatory function in adults only. To address these gaps in our current knowledge, this study raised Sprague Dawley rats (n = 42) in four dietary cohorts from weaning to skeletal maturity. Two cohorts were fed a stable (“annual”) diet of either solid or powdered pellets. The other two cohorts were fed a variable (“seasonal”) diet consisting of solid/powdered pellets for the first half of the study, followed by a shift to the opposite diet. Results of longitudinal morphometric analyses indicate that variation in the mandibular corpus is more prominent at immature ontogenetic stages, likely due to processes of dental eruption and the growth of tooth roots. Furthermore, adult morphology is influenced by both masticatory function and the ontogenetic timing of this function, e.g., the consumption of a mechanically resistant diet. The morphology of the coronoid process was found to separate cohorts on the basis of their early weanling diet, suggesting that the coronoid process/temporalis muscle module may have an early plasticity window related to high growth rates during this life stage. Conversely, the morphology of the angular process was found to be influenced by the consumption of a mechanically resistant diet at any point during the growth period, but with a tendency to reflect the most recent diet. The prolonged plasticity window of the angular process/pterygomasseteric muscle module may be related to delayed ossification and muscular maturation within this module. The research presented here highlights the importance of more naturalistic models of mammalian feeding, and underscores the need for a better understanding of the processes of both morphological and behavioral maturation that follow weaning.
AB - The material properties of diets consumed by juvenile individuals are known to affect adult morphological outcomes. However, much of the current experimental knowledge regarding dietary effects on masticatory form is derived from studies in which individuals are fed a non-variable diet for the duration of their postweaning growth period. Thus, it remains unclear how intra-individual variation in diet, due to ontogenetic variation in feeding behaviors or seasonal resource fluctuations, affects the resulting adult morphology. Furthermore, the mandible is composed of multiple developmental and functional subunits, and the extent to which growth and plasticity among these modules is correlated may be misestimated by studies that examine non-variable masticatory function in adults only. To address these gaps in our current knowledge, this study raised Sprague Dawley rats (n = 42) in four dietary cohorts from weaning to skeletal maturity. Two cohorts were fed a stable (“annual”) diet of either solid or powdered pellets. The other two cohorts were fed a variable (“seasonal”) diet consisting of solid/powdered pellets for the first half of the study, followed by a shift to the opposite diet. Results of longitudinal morphometric analyses indicate that variation in the mandibular corpus is more prominent at immature ontogenetic stages, likely due to processes of dental eruption and the growth of tooth roots. Furthermore, adult morphology is influenced by both masticatory function and the ontogenetic timing of this function, e.g., the consumption of a mechanically resistant diet. The morphology of the coronoid process was found to separate cohorts on the basis of their early weanling diet, suggesting that the coronoid process/temporalis muscle module may have an early plasticity window related to high growth rates during this life stage. Conversely, the morphology of the angular process was found to be influenced by the consumption of a mechanically resistant diet at any point during the growth period, but with a tendency to reflect the most recent diet. The prolonged plasticity window of the angular process/pterygomasseteric muscle module may be related to delayed ossification and muscular maturation within this module. The research presented here highlights the importance of more naturalistic models of mammalian feeding, and underscores the need for a better understanding of the processes of both morphological and behavioral maturation that follow weaning.
KW - Dietary variability
KW - Fallback foods
KW - Mammals
KW - Phenotypic plasticity
UR - http://www.scopus.com/inward/record.url?scp=85026369301&partnerID=8YFLogxK
U2 - 10.1016/j.zool.2017.05.009
DO - 10.1016/j.zool.2017.05.009
M3 - Article
C2 - 28774721
AN - SCOPUS:85026369301
SN - 0944-2006
VL - 124
SP - 61
EP - 72
JO - Zoology
JF - Zoology
ER -