Frugivory and taste responses to fructose and tannic acid in a prosimian primate and a didelphid marsupial

The taste responses to sweet and astringent compounds were investigated in two mammals of similar ecology, by using the classical method of the two-bo ttle test. The taste threshold for fructose was higher in Microcebus murinu s, a prosimian primate, than in Caluromys philander, a didelphid marsupial. The profiles of suprathreshold responses resembled a dissymmetric bell-sha ped curve, but the rate of consumption of sweet solutions up to maximal int ake increased more rapidly in Microcebus than in Caluromys. Despite showing a photoperiod-synchronized physiology, Microcebus displayed no seasonal va riation of the taste threshold and suprathreshold responses. The depressing effect of tanning acid on the ingestion of fructose solutions increased pr ogressively with tannin concentration and was lower as fructose concentrati on increased. Inhibition thresholds for tannic acid were similar between th e two species. The data suggest that adaptation to frugivorous diets is ass ociated with globally similar shaping of the taste responses, even though s ubtle differences of palatability may account for differences of feeding se lectivity.