Data from: Loss of sweet taste despite the conservation of sweet receptor genes in insectivorous bats

The evolution of taste perception is usually associated with the ecology
and dietary changes of organisms. However, mismatches between feeding
ecology and taste receptor evolution have been identified in some
vertebrate animals. One example is the sweet taste receptor gene Tas1r2.
Previous analysis of partial sequences has revealed that Tas1r2 has
undergone equally strong purifying selection between insectivorous and
frugivorous bats. To test whether the sweet taste function is also
important in bats with contrasting diets, we examined the complete coding
sequences of both sweet taste receptor genes (Tas1r2 and Tas1r3) in 34
representative bat species. Although these two genes are highly conserved
between frugivorous and insectivorous bats at the sequence level, our
behavioral experiments revealed that an insectivorous bat (Myotis
ricketti) showed no preference for natural sugars, whereas the frugivorous
species (Rousettus leschenaultii) showed strong preferences for sucrose
and fructose. Furthermore, while both sweet taste receptor genes are
expressed in the taste tissue of insectivorous and frugivorous bats, our
cell-based assays revealed striking functional divergence: the sweet taste
receptors of frugivorous bats are able to respond to natural sugars
whereas those of insectivorous bats are not, which is consistent with the
behavioral preference tests, suggesting that functional evolution of sweet
taste receptors is closely related to diet. This comprehensive study
suggests that using sequence conservation alone could be misleading in
inferring protein and physiological function, and highlights the power of
combining behavioral experiments, expression analysis, and functional
assays in molecular evolutionary studies.