Effect of plant traits and network metrics on pollen limitation in hummingbird-pollinated plants from the Brazilian Campos Rupestres

Abstract

Pollen limitation (PL) can be an important estimate of the contribution of pollinators to the reproductive success of plants. PL often varies between species within the same community, and interspecific variation in PL may be related to plant traits and interaction patterns. However, few studies have investigated its drivers at the community level. In this study we assessed PL and its relationship with the dependence of plants on pollinators, floral morphology, nectar production and descriptors of the role of plant species in the interaction network in which they are embedded (linkage level, interaction strength, specialization and c or z coefficients) for 28 plant species pollinated by hummingbirds in the Brazilian Campos Rupestres. In the studied plant community, the prevalence of PL was high, but intensity was low, with 8 species (29 %) presenting some degree of PL. Nectar volume and nectar concentration were negatively related to PL, while plant species with higher dependence on pollinators for reproduction presented higher PL. We did not detect a relationship between network metrics and pollen limitation, this could reflect the low variation in species roles in the community, with most plant species being peripherals (linked to few and generalized pollinators). We demonstrated that plant traits were more important than network metrics in predicting interspecific variation in pollen limitation in the studied plant-hummingbird network. We suggest that evaluating pollen limitation within plant communities is key to uncover the drivers of pollination deficits.