Nectar secretion patterns are associated to nectar accessibility in a guild of crepuscular-nocturnal flowering plants

Abstract

Floral morphology can determine the type of animal that can be an effective pollinator. In flowers with nocturnal anthesis long-tubed flowers may attract long-tongued insects such as hawkmoths. However, flowers with more open morphology have nectar that can be more easily accessed by bats and short-tongued moths. These contrasting conditions may have consequences on nectar characteristics, since bats can mediate the selection of copious nectar with low to medium sugar concentration values, contrary to what occurs in hawkmoth-pollinated flowers that show comparatively lower nectar volumes with medium sugar concentrations. Here we describe an overview of the nectar features, secretion patterns and removal effects in a guild of plants with crepuscular-nocturnal anthesis in the Atlantic Forest, Northeastern Brazil. Such a plant set encompassed both species with restricted and easy access to nectar, i.e., long-tube flowers and brush-type flowers, respectively. We found a marked difference between attributes of nectar between both groups. Long-tube flowers offer nectar of higher sugar concentration at specific periods of the night that can be reabsorbed later if it has not been removed, the brush-type flowers provide nectar of low sugar concentrations, throughout the night, and may increase their production in response to consumption. These differences can play an important role in mechanisms related to the sharing of resources in the community, ensuring an even more intimate relationship between long-tube flowers and hawkmoths, and allowing brush-type flowers to deal with consumption by different nocturnal pollinators.