COS 90-5 - Facilitation not competition in plant-pollinator mutualisms: Staggered diurnal flower blooming period in three Malvacean species supports facilitation hypothesis

Wednesday, August 9, 2017: 9:20 AM
D131, Oregon Convention Center


Sangeetha Varma, Central University of Kerala; Palatty Allesh Sinu, Central University of Kerala


Plant-pollinator mutualism can be substantially destabilized if co-flowering species compete for the service of shared pollinators. In herbaceous plant communities, competition is more prevalent than the facilitation. One mechanism that leads to facilitation is adjusting flowering phenology among plant species. Plants adjust their blooming period in different seasons, months or even within a day to attract maximum specialist and generalist pollinator species. While studies that have investigated the plants that bloom in different months/ seasons are plenty, how the plant species in a given day adjust each other for getting the service of shared pollinators is not studied in detail. We monitored pollinator fauna in populations of three species of Malvaceae – two closely related species, Sida rhombifolia (blooming period: 0800 – 1100h) and Sida cordifolia (0930 – 1330 h), and Triumfetta rhomboidea (1530 – 1830 h) in communities for three years to study whether the different blooming periods help them to use the shared pollinators efficiently. We have analyzed the species richness and visitation rate of total visitors, the specialist bee community and the generalist butterflies and moths in three plant species.


Together the three plant species received visits from 74 insects, predominantly bees. The visitation rate of overall visitors was high in T. rhomboidea (p=0.004).But, the number of species visited the flowers of three species remained same (p=0.21). Neither the specialist bee visitor richness (p=0.78) nor bee visitation rate (p=0.17) differed significantly between plant species regardless of their different blooming periods. Although insignificant, visitation rate was high in T. rhomboidea than the Sida spp. This is because during afternoon hours only very few plant species do bloom and compete for the shared pollinators. The non-bee visitor richness was high in Sida rhombifolia than the other two species (p=0.019), but the visitation rates remained same across the three species (p=0.68). The generalist nectar foraging butterfly and moth richness (p=0.07) and visitation rate (p=0.02) were marginally significantly low in T. rhomboidea. There was a significant overlap in the visitor species that tripped to the three plant species, suggesting that the staggered blooming had helped the three plant species to share the available insect pollinators.