Abstract
Vertebrates can perceive at least five different taste qualities, each of which is thought to have a specific role in the evolution of different species. The avoidance of potentially poisonous foods, which are generally bitter or sour tasting, and the search for more nutritious ones, those with high-fat and high-sugar content, are two of the most well-known examples. The study of taste genes encoding receptors that recognize ligands triggering taste sensations has helped to reconstruct several evolutionary adaptations to dietary changes. In addition, an increasing number of studies have focused on pseudogenes, genomic DNA sequences that have traditionally been considered defunct relatives of functional genes mostly because of the presence of deleterious mutations interrupting their open reading frames. The study of taste receptor pseudogenes has helped to shed light on how the evolutionary history of taste in vertebrates has been the result of a succession of gene gain and loss processes. This dynamic role in evolution has been explained by the “less-is-more” hypothesis, suggesting gene loss as a mechanism of evolutionary change in response to a dietary shift. This mini-review aims at depicting the major lineage-specific loss of function of taste receptor genes in vertebrates, stressing their evolutionary importance and recapitulating signatures of natural selection and their correlations with food habits.
Highlights
Pseudogenes have historically been considered genomic fossils and junk DNA, because of their classic definition of non-functional sequences of genomic DNA, originally derived from functional genes, but containing mutations or lacking promoter sequences precluding their expression (Wilde, 1986; Balakirev and Ayala, 2003)
Multiple studies highlighted how pseudogenes have had a remarkable functional plasticity and a dynamic role in species’ evolution (Bekpen et al, 2009; Korrodi-Gregório et al, 2013; Risso et al, 2014): chemosensory genes, in particular, have been characterized by a succession of birth-and-death processes in different lineages (Dong et al, 2009a,b). The aim of this mini-review is to provide an integrative view of the evolutionary history of taste receptor genes, with a focus on the main gene losses that have occurred in different lineages, pinpointing the genetic and biological factors driving these episodes
Most authors primarily focused on vertebrates, a few studies highlighted the presence of a large G protein-coupled receptors (GPCRs) gene family in Drosophila named Gustatory Receptor (GR) which shows a differential expression in feeding-related tissues and confers a fine taste sensitivity to a broad range of alkaloids and other bitter compounds (Chapman et al, 1991; Glendinning and Hills, 1997; Clyne et al, 2000)
Summary
Specialty section: This article was submitted to Structural Biology, a section of the journal Frontiers in Molecular Biosciences. The study of taste receptor pseudogenes has helped to shed light on how the evolutionary history of taste in vertebrates has been the result of a succession of gene gain and loss processes This dynamic role in evolution has been explained by the “less-is-more” hypothesis, suggesting gene loss as a mechanism of evolutionary change in response to a dietary shift. This mini-review aims at depicting the major lineage-specific loss of function of taste receptor genes in vertebrates, stressing their evolutionary importance and recapitulating signatures of natural selection and their correlations with food habits
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
