2018 ESA Annual Meeting (August 5 -- 10)

COS 66-7 - Heavy dominance of non-native pollinators in a Hawaiian dry forest ecosystem

Wednesday, August 8, 2018: 10:10 AM
357, New Orleans Ernest N. Morial Convention Center
Clare E. Aslan, Lab of Landscape Ecology and Conservation Biology, Northern Arizona University, Flagstaff, AZ, Christina T. Liang, USDA Forest Service, Pacific Southwest Research Station, Hilo, HI, Aaron B. Shiels, USDA APHIS, National Wildlife Research Center, Fort Collins, CO and William P. Haines, Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, Honolulu, HI
Background/Question/Methods

On oceanic islands, simplified biotas, high endemism, and rampant human modification have resulted in high extinction rates among native species. These extinctions may disrupt critical species interactions. Disruptions in interactions such as pollination may place additional species at risk of secondary extinctions or extinction cascades. At the same time, high rates of establishment by non-native species on islands may introduce new interaction partners and result in novel ecological communities. We conducted a two-year study of eight endemic plant species in a high-elevation Hawaiian dry forest ecosystem to identify their pollinators. Four of these plant species are Endangered, and our observations were designed to determine whether pollination disruption was contributing to poor reproduction among those species. We additionally performed manual pollination treatments to determine whether plants are self-compatible and to quantify pollen limitation.

Results/Conclusions

All focal plant species set seed during our observational study. Our manual pollination treatments confirmed that all species are self-compatible, with Index of Self-Incompatibility (ISI) values ranging from 0.18 to 0.80. Pollen Limitation Index (PLI) values were generally higher for the Endangered plant species than for the common endemic species. Most notably, the large majority of observed visitation to endemic plants (85.5%), prior to predator exclusion, was performed by non-native flower visitors. Indeed, two of the Endangered plant species (Silene lanceolata and Stenogyne angustifolia) were visited exclusively by non-native species. These results highlight the importance of non-native species as positive interactors with endemic plants in this system. Furthermore, Endangered plant species in this system appear to be receiving relatively less pollination than common species and to be particularly dependent on non-native flower visitors. This system exemplifies a novel ecological community heavily influenced by non-native species.