Molecular Evolution of Tooth-Related Genes Provides New Insights into Dietary Adaptations of Mammals

Abstract

Mammals have evolved different tooth phenotypes that are hypothesized to be associated with feeding habits. However, the genetic basis for the linkage has not been well explored. In this study, we investigated 13 tooth-related genes, including seven enamel-related genes (AMELX, AMBN, ENAM, AMTN, ODAM, KLK4 and MMP20) and six dentin-related genes (DSPP, COL1A1, DMP1, IBSP, MEPE and SPP1), from 63 mammals to determine their evolutionary history. Our results showed that different evolutionary histories have evolved among divergent feeding habits in mammals. There was stronger positive selection for eight genes (ENAM, AMTN, ODAM, KLK4, DSPP, DMP1, COL1A1, MEPE) in herbivore lineages. In addition, AMELX, AMBN, ENAM, AMTN, MMP20 and COL1A1 underwent accelerated evolution in herbivores. While relatively strong positive selection was detected in IBSP, SPP1, and DSPP, accelerated evolution was only detected for MEPE and SPP1 genes among the carnivorous lineages. We found positive selection on AMBN and ENAM genes for omnivorous primates in the catarrhini clade. Interestingly, a significantly positive association between the evolutionary rate of ENAM, ODAM, KLK4, MMP20 and the average enamel thickness was found in primates. Additionally, we found molecular convergence in some amino acid sites of tooth-related genes among the lineages whose feeding habit are similar. The positive selection of related genes might promote the formation and bio-mineralization of tooth enamel and dentin, which would make the tooth structure stronger. Our results revealed that mammalian tooth-related genes have experienced variable evolutionary histories, which provide some new insights into the molecular basis of dietary adaptation in mammals.

Biphasic Functions of Sodium Fluoride (NaF) in Soft and in Hard Periodontal Tissues

“…MMP-20 is produced at the secretory stage of dental enamel formation and cleaves proteins that allow the crystals to grow into the space [15]. Ameloblasts also secrete kallikrein-4 (KLK4), which is essential for the breakdown of enamel proteins and enamel crystallization [16]. KLK4 helps crystals to grow and contract, which strengthens the enamel at the last stage of amelogenesis [16].…”

“…Ameloblasts also secrete kallikrein-4 (KLK4), which is essential for the breakdown of enamel proteins and enamel crystallization [16]. KLK4 helps crystals to grow and contract, which strengthens the enamel at the last stage of amelogenesis [16].…”

The rough‐toothed dolphin genome provides new insights into the genetic mechanism of its rough teeth

“…2019; Mu et al. 2021b). One hypothesis thought these inactivating mutations may relate to their simplified outer enamel surface (Springer et al.…”

“…The genus Kogia in Odontoceti also owned enamel-less teeth, which was likely due to the inactivation of ACP4, AMBN, ENAM, and MMP20 (Mu et al 2021a;Randall et al 2022). Furthermore, the ODAM is also inactivated in all odontocetes (Springer et al 2019;Mu et al 2021b). One hypothesis thought these inactivating mutations may relate to their simplified outer enamel surface (Springer et al 2019).…”

Tooth Diversity Underpins Future Biomimetic Replications

“…Other rock scrapers such as chiton, maximize the hardness by choosing iron oxide as the biominerals [ 28 , 29 , 30 ]. Among mammals, different feeding habits of herbivores and carnivores alter the ultrastructure of their teeth to select for their most critical functions, such as anti-wear, antifatigue, and anti-fracture [ 24 , 31 , 32 ]. Knowledge on tooth diversity is, therefore, as important as their conservation in understanding and imitating the optimized hypermineralized structures for desirable applications.…”