Nutrient acquisition across a dietary shift: fruit feeding butterflies crave XXXX , nectivores seek salt.

@entity1522 @entity1568 @entity1372 @entity5819
UNASSIGNED: Evolutionary dietary shifts have major ecological consequences. One likely consequence is a change in nutrient limitation-some nutrients become more abundant in the diet, others become more scarce. Individuals' behavior should change accordingly to match this new limitation regime: they should seek out nutrients that are deficient in the new diet. We investigated the relationship between diet and responses to nutrients using adult Costa Rican butterflies with contrasting feeding habits, testing the hypothesis that animals will respond more positively to nutrients that are scarcer in their diets. Via literature searches and our own data, we showed that @entity1568 and @entity1372 are both at lower concentration in nectar than in fruit. We therefore assessed butterflies' acceptance of @entity1372 and four nitrogenous compounds that ranged in complexity from inorganic @entity1568 ( @entity5819 ) to protein (albumin). We captured wild butterflies, offered them aqueous solutions of each substance, and recorded whether they accepted (drank) or rejected each substance. Support for our hypothesis was mixed. Across the sexes, frugivores were four times more likely to accept @entity1522 (hydrolyzed casein) than nectivores, in opposition to expectation. In males, nectivores accepted @entity1372 almost three times more frequently than frugivores, supporting expectations. Together, these results suggest that in butterflies, becoming frugivorous is associated with an increased receptivity to @entity1522 and decreased receptivity to @entity1372 . Nectivory and frugivory are widespread feeding strategies in organisms as diverse as insects, birds, and bats; our results suggest that these feeding strategies may put different pressures on how animals fulfill their nutritional requirements.
