Positive Selection Linked with Generation of Novel Mammalian Dentition Patterns.
A diverse group of genes are involved in the tooth development of mammals. Several studies, focused mainly on mice and rats, have provided a detailed depiction of the processes coordinating tooth formation and shape. Here we surveyed 236 tooth-associated genes in 39 mammalian genomes and tested for signatures of selection to assess patterns of molecular adaptation in genes regulating mammalian dentition. Of the 236 genes, 31 (∼13.1%) showed strong signatures of positive selection that may be responsible for the phenotypic diversity observed in mammalian dentition. Mammalian-specific tooth-associated genes had accelerated mutation rates compared with older genes found across all vertebrates. More recently evolved genes had fewer interactions (either genetic or physical), were associated with fewer Gene Ontology terms and had faster evolutionary rates compared with older genes. The introns of these positively selected genes also exhibited accelerated evolutionary rates, which may reflect additional adaptive pressure in the intronic regions that are associated with regulatory processes that influence tooth-gene networks. The positively selected genes were mainly involved in processes like mineralization and structural organization of tooth specific tissues such as enamel and dentin. Of the 236 analyzed genes, 12 mammalian-specific genes (younger genes) provided insights on diversification of mammalian teeth as they have higher evolutionary rates and exhibit different expression profiles compared with older genes. Our results suggest that the evolution and development of mammalian dentition occurred in part through positive selection acting on genes that previously had other functions.
CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal Abel Salazar Biomedical Sciences Institute (ICBAS), University of Porto, Porto, Portugal.
João Paulo
JP
Machado
CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal.
Siby
S
Philip
CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal.
Emanuel
E
Maldonado
Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia Oceanographic Center, Nova Southeastern University, Ft Lauderdale.
Stephen J
SJ
O'Brien
Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia, USA.
Warren E
WE
Johnson
CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal Abel Salazar Biomedical Sciences Institute (ICBAS), University of Porto, Porto, Portugal Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal aantunes@ciimar.up.pt.
Agostinho
A
Antunes
D000818:Animals; D003817:Dentition; D008322:Mammals / Q000145:classification / Q000235:genetics; D059645:Mutation Rate; D010802:Phylogeny; D012641:Selection, Genetic; D059467:Transcriptome
adaptive evolution; mammalian dentition genes; positive selection; teeth; tooth-associated genes