Quantitative genetic analyses of postcanine morphological crown variation

Abstract

Objectives: This article presents estimates of narrow-sense heritability and bivariate genetic correlation for 14 tooth crown morphological variants scored on permanent premolars, first molars, and second molars. The objective is to inform data collection and analytical practices in dental biodistance and to provide insights on the development of molar crowns as integrated structures.Materials and Methods: African American dental casts from the Menegaz-Bock collection were recorded for the Arizona State University Dental Anthropology System. Estimates of narrowsense heritability and genetic correlation were generated using SOLAR v.8.1.1, which included assessment of age, sex, and birth year as covariates. Both continuous scale and dichotomized estimates are provided.Results: Heritability estimates were nonsignificant for the majority of variables; however, for variables yielding significant estimates, values were moderate to high in magnitude and comparable to previous studies. Comparing left and right-side heritability estimates suggests directional asymmetry in the expression of environmental variance, something not seen in anterior tooth traits. Genetic correlations were moderate among antimeres and metameres and low for different traits scored on the same tooth crown. Although several negative correlations were noted, few reached statistical significance. Results affirm some of the current data cleaning and analytical practices in dental biodistance, but others are called into question. These include the pooling of males and females and combining left and right-side data into a single dataset.Conclusions: In comparison to anterior tooth crown traits, postcanine heritabilities were more often non-significant; however, those traits with significant heritability also tended to produce higher estimates. Genetic correlations were unremarkable, in part, because they were underpowered. However, M1 results may provide insight into the complex relationship between genes, environment, and development in determining ultimate crown form. K E Y W O R D Sbiodistance, dental morphology, heritability, pleiotropy, quantitative genetics

Testing the utility of dental morphological trait combinations for inferring human neutral genetic variation

“…However, to our knowledge, such approaches have not yet been applied to the various dental morphological traits of the ASUDAS. Moreover, whereas previous genotype-phenotype investigations on cranial elements used predefined functional and developmental modules, such study design might be suboptimal in light of the complex modularity, ontogeny, and inheritance of phenotypes in general, and dental traits in particular (21,22,(29)(30)(31)(32). We therefore propose that testing all possible combinations of dental traits in preserving neutral genetic signals is a more promising approach than restricting analyses to only individual traits or predefined trait combinations.…”

“…However, it is debated whether certain dental traits preserve neutral genetic signatures to a greater degree than others (20)(21)(22), and until now, there is no definitive list of key dental traits that are most useful for adequately capturing neutral genomic variation (15). As a rule of thumb, researchers therefore assume that phenotypic analyses based on many dental traits are more reliable than those based on only a few traits (14,15).…”

Genetic correlations in the dental dimensions ofSaguinus fuscicollis

“…Phenotypic similarities in dental morphology are therefore frequently used to approximate ancestor–descendant relationships, serving as proxies for genetic data that are unavailable in the fossil record. The use of dental traits in phylogenetic reconstruction is supported by the high heritabilities estimated from primate dental traits (Hardin, ; Hlusko, ; Hlusko & Mahaney, , ; Hlusko, Weiss, & Mahaney, ; Stojanowski, Paul, Seidel, Duncan, & Guatelli‐Steinberg, , ; Stojanowski, Paul, Seidel, Guatelli‐Steinberg, & Duncan, ). Quantitative genetic analyses can also bridge the gap between theories of mammalian dental patterning (Butler, ; Dahlberg, ; Evans et al, ; Kavanagh, Evans, & Jernvall, ; Osborn, ) and evaluations of phenotypic variation and covariation in primate taxa (Delezene, ; Gómez‐Robles, Smaers, Holloway, Polly, & Wood, ; Strait & Grine, ) to improve our understanding of the impact of genetic patterning on dental evolution (Hlusko, Schmitt, Monson, Brasil, & Mahaney, ).…”

The landscape of tooth shape: Over 20 years of dental topography in primates

“…Here, the biggest challenge lies in gaining a pedigreed collection of unworn dental molds: worn teeth cannot be used for these purposes, as their shape is a product of genetic and environmental factors. 94…”

“…This is necessary to construct evolutionary models to (a) understand how selection is acting on dental topography and (b) perform more accurate dietary reconstructions, by understanding how long it takes teeth to become adapted to diet. Here, the biggest challenge lies in gaining a pedigreed collection of unworn dental molds: worn teeth cannot be used for these purposes, as their shape is a product of genetic and environmental factors 94 …”