Pollination generalization and reproductive assurance by selfing in a tropical montane ecosystem.

Abstract

Pollination and reproduction are important processes for understanding plant community dynamics. Information regarding pollination and reproduction is urgent for threatened ecosystems, such as tropical montane ecosystems. In tropical mountains, pollination patterns are expected to conform to the reproductive assurance theory (due to low pollinator activity) and old, climatically buffered and infertile landscapes (OCBIL) theory (due to restricted plant range size). For 82 plant species of the Itatiaia National Park (including endemic and endangered species), we evaluated at least one of the following features: pollinator identity, flower color and size, flowering phenology, and pollinator dependence. Most plant species (ca. 60%) were pollinated by two or more functional groups of pollinators (generalized pollination), with high importance of flies as pollinators. There was low pollinator activity overall (less than one visit per flower per hour). Notably, the invasive honeybee Apis mellifera L. performed half of the visits to this entire plant community, suggesting an impact on the native pollinator fauna and consequently on the native flora. Most endemic plants were generalized with white and small flowers, while endangered species were pollination-specialized with colorful and large flowers. Thus, endangered species are susceptible to changes in pollinator fauna. Flowering seasonality reflected the importance of climatic constraints in this environment. One-third of the plant species were autogamous. Our data suggest that pollinator scarcity may have promoted reproductive assurance strategies such as generalization and pollinator independence. Our community-level study highlighted consistent pollination patterns for tropical mountains and emphasized threats for specialized endangered species.