The reproductive biology of Dyckia scrutor (Bromeliaceae): an endangered species endemic to Campos Rupestres

Pollinators are crucial for the conservation of endangered species, providing essential ecosystem services that support plant reproduction. Dyckia scrutor is an endangered species of bromeliad endemic to Campos Rupestres. The genus Dyckia presents species pollinated by both nocturnal and diurnal visitors, with bats and hummingbirds as the most important pollinators. However, the few existing studies about D. scrutor make it difficult to take action to preserve the species. This study aims to describe the floral biology of D. scrutor and identify the contribution of nocturnal and diurnal pollinators to the species’ reproductive success. We monitored reproductive phenology, floral longevity, nectar dynamics, floral visitors, pollinator dependence, pollen limitation, and the relative contribution of nocturnal and diurnal visitors. Although the plant produces seeds in the absence of pollinators, their presence increases production. D. scrutor showed some degree of pollen limitation, and the main floral visitors were the hummingbird Augastes scutatus and Strymon butterflies. Although we observed no nocturnal visits, the number of seeds in flowers open to nocturnal pollinators was higher than in those bagged, indicating that nocturnal pollination occurs. However, the contribution of daytime visitors to seed formation was greater. Our work highlights a case of doubly threatened interaction, in which an endangered plant species of restricted range appears to rely primarily on a hummingbird that is also endemic. These results suggest the need for special and cautious measures to preserve this interaction and consequently, the species involved.