Intraspecific variability of nectar attracts different bats: the case of Pseudalcantarea viridiflora, a bromeliad with crepuscular anthesis

ABSTRACT Intraspecific variation in floral traits, such as nectar, could lead to differences in the identity and pollinator effectiveness of visitors between populations of a flowering plant. We studied the bat-pollinated bromeliad species Pseudalcantarea viridiflora to determine whether there are differences in the identity of its pollinators and in its nectar traits between two study sites located at different latitudes in Veracruz, Mexico. We studied phenology and determined the volume, concentration and quantity of dissolved sugars in the nectar at both sites. The northern P. viridiflora population produced nectar that was more sugar-rich, leading to pollination by a larger species, Anoura geoffroyi, whereas the southern populations were visited mainly by Glossophaga mutica, a smaller pollinator. The most abundant nectarivorous bats at each site differ in terms of their efficiency as pollinators, and we suggest that this might affect their contribution to the fitness of the bromeliad.

摘要：花性状（floral traits，如花蜜（nectar））的种内变异（intraspecific variation），可导致开花植物不同种群间传粉者类群及其传粉效率（pollinator effectiveness）产生差异。本研究以蝙蝠传粉的（bat-pollinated）凤梨科植物（bromeliad）绿花假帝王凤梨（*Pseudalcantarea viridiflora*）为研究对象，旨在明确墨西哥韦拉克鲁斯州（Veracruz）两个不同纬度研究样地中，该物种的传粉者类群组成与花蜜性状是否存在差异。我们在两处样地均开展了物候（phenology）观测，并测定了花蜜的体积、浓度及总溶解糖含量（quantity of dissolved sugars）。结果显示，北部的*P. viridiflora*种群所产花蜜含糖量更高，其主要传粉者为体型更大的杰氏长舌蝠（*Anoura geoffroyi*）；而南部种群的主要传粉者则为体型较小的穆氏舌蝠（*Glossophaga mutica*）。两处样地中占优势的食花蜜蝙蝠（nectarivorous bats）类群，其传粉效率存在差异，我们据此推测该差异可能会影响其对该凤梨科植物适合度（fitness）的贡献。