Genetic correlations in the dental dimensions ofSaguinus fuscicollis

Abstract

Objectives: The objectives of this study are to describe genetic correlations between dental dimensions in a platyrrhine primate, to assess whether the brown-mantled tamarin dentition exhibits genetic modularity by tooth type, and to discuss the relationship between body size reduction and the genetic architecture of dental traits.Materials and methods: Genetic correlations were estimated for linear dental measurements, estimated crown areas, and measures of relative premolar and molar size from 302 individuals, using a pedigree of 386 individuals, with maximum likelihood variance decomposition in SOLAR.Results: Genetic correlation estimates indicate strong genetic integration in the dentition of brown-mantled tamarins, with little evidence of modularity by tooth type, within and between the maxilla and mandible. The relative molar size variable hypothesized to be genetically patterned in baboons is not significantly heritable, and relative premolar size does not meet the criteria to be considered genetically patterned in this population.Discussion: These results demonstrate variation in the pattern of genetic correlations between dental dimensions in primates, providing evidence of evolution of the genetic architecture in the callitrichine lineage. Genetic integration of dental dimensions without modularity by tooth type, as demonstrated here, is expected to constrain dental evolution in ways that modularity would not. The role of body size reduction in the callitrichine lineage in the evolution of the genetic architecture of the dentition is discussed. Quantitative genetic analyses of dental dimensions in more primate populations will provide greater evidence of variation and evolution in the genetic architecture underlying primate dental morphology.

Conserved and Taxon-Specific Patterns of Phenotypic Modularity in the Mammalian Dentition

“…2019 ). Placing this into context with the higher degree of integration and lack of modularity similarly observed for tamarins ( Hardin 2019 ), perhaps post-canine modularity is readily responsive to selective pressures over evolutionary time, dissipating and reformulating in different patterns. The results from our analysis of two carnivores support this idea.…”

“…We also excluded the canines because they were not included in the baboon quantitative genetic analyses ( Hlusko et al. 2011 ) and their modular structure is uncertain ( Hardin 2019 , 2020 ; Paul et al. 2021 ).…”

“…2013 ). While quantitative genetic analyses of dental variation in brown-mantled tamarins ( Hardin 2019 ) do not reveal evidence of genetic modularity, it is possible that the dramatic body size reduction in tamarins may have resulted in a derived dental genetic architecture.…”

Genetic Correlation, Pleiotropy, and Molar Morphology in a Longitudinal Sample of Australian Twins and Families

“…With regard to understanding the structure of mammalian dentitions, this work has provided crucial insight into the role of genes in partitioning the tooth row into distinct modules. While many studies have focused on tooth size in human and non-human primates [ 22 , 23 , 24 , 25 , 26 ], some efforts have centered around non-metric crown variants, shape variables, and cusp configuration [ 17 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…Submodularity (premolar/molar) in the postcanine dentition is also consistent with predictions outlined by Butler’s morphogenetic field model [ 33 , 34 , 35 ]. However, a higher degree of genetic integration across fields has been reported for some primate populations [ 22 , 26 ]. The genetic architecture of human crown variation, in many cases, supports morphogenetic field effects, with the anterior-most member of each field characterized by higher heritability estimates [ 26 ] and traits expressed on neighboring teeth characterized by high genetic correlation estimates [ 31 ].…”