title: Diet shapes the evolution of the vertebrate bitter taste receptor gene repertoire.
abstract: Vertebrate Tas2r taste receptors bind to bitter compounds, which are typically poisonous, to elicit bitter sensation to prevent the ingestion of toxins. Previous studies noted a marked variation in the number of Tas2r genes among species, but the underlying cause is unclear. To address this question, we compile the Tas2r gene repertoires from 41 mammals, 4 birds, 2 reptiles, 1 amphibian, and 6 fishes. The number of intact Tas2r genes varies from 0 in the bottlenose dolphin to 51 in the Western clawed frog, with numerous expansions and contractions of the gene family throughout vertebrates, especially among tetrapods. The Tas2r gene number in a species correlates with the fraction of plants in its diet. Because plant tissues contain more toxic compounds than animal tissues do, our observation supports the hypothesis that dietary toxins are a major selective force shaping the diversity of the Tas2r repertoire.
authors.affiliation: College of Animal Science and Technology, Sichuan Agricultural University, Ya'an, Sichuan, China.
authors.forename: Diyan
authors.initials: D
authors.lastname: Li
authors.forename: Jianzhi
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004032:Diet; D019143:Evolution, Molecular; D014644:Genetic Variation; D010802:Phylogeny; D010944:Plants / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D012641:Selection, Genetic; D013045:Species Specificity; D013649:Taste / Q000235:genetics*; D014118:Toxins, Biological / Q000378:metabolism*; D014714:Vertebrates / Q000235:genetics*; D000098706:Taste Receptors, Type 2
chemical_list: D043562:Receptors, G-Protein-Coupled; D014118:Toxins, Biological; D000098706:Taste Receptors, Type 2
keywords: Tas2r; bitter taste receptor; carnivore; herbivore; omnivore