Abstract Detail

Studying Plant Pollinator Interactions in Changing Environments: Approaches, Lessons and Future Directions

DeMariano, Audra J. [1], Miller-Struttmann, Nicole [2], Hoch, Peter C. [3], Krakos, Kyra N. [4].

Historical pollen data as a comparative tool in climate change studies.

Changes in flowering abundance and composition are altering historical patterns in plant-pollinator relationships. As pollinators respond to changes in climate, fire management, and/or land-use, the quality of pollination services they provide is predicted to shift. In a woodland-grassland mosaic landscape at Shaw Nature Reserve (SNR) in eastern Missouri, most species flower earlier, and co-flowering diversity has increased, particularly later in the growing season. Competition for pollinators increases with flower diversity, all else being equal, and plant reproductive success could suffer. To fully understand the impacts of changes in plant phenology on these relationships, historical data on pollinator behavior are required. However, it is rare to have data on both flowering phenology and pollinator behavior at the same location. Here we leverage archived specimens of five bee species collected over a 70-year span at or near SNR to determine if and how pollinator foraging behavior changes in response to changing phenology. Pollen was removed from insects using a non-destructive technique and identified using a pollen library. Pollen load analyses provide deeper insights into pollinator foraging behavior than visitation records alone by dissociating pollen and nectar foraging. We assessed changes in pollen load size through time using linear regression. To test for effects of pollen load size on pollen diversity, we used multiple regression, with pollen load size and time as continuous factors. When pooled across species, pollen load did not vary through time. However, temporal shifts in pollen load size vary by species, indicating that data from multiple pollinator species are needed for complete analysis. Pollen load size decreased over time for two species (Andrena carlini and Augochlora pura), increased for Apis mellifera, and remained constant for two Bombus species. Pollen diversity increased with load size, indicating that analyses should measure both diversity and load size. After accounting for differences in pollen load size, diversity of pollen carried decreased through time in three of the five bee species, contrary to prediction. Deposition of less heterospecific pollen may lead to improved pollination services, enhancing plant reproductive success. Theseresults suggest that archived specimens can be used to explore changes in pollinator foraging behavior, since pollen carried can be compared with pollen on individuals of the same taxa in the same plant communities through time. Archived insect collections can provide insights into changing plant-pollinator partnerships due to species invasions, climate change, and land-use change, provided that detailed records and repeat collections exist.

1 - Maryville University, St. Louis, Missouri, USA
2 - SUNY College at Old Westbury, Biological Science Dept., Old Westbury, NY, 11568, USA
3 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166-0299, USA
4 - Maryville University, Department of Biology, 650 Maryville University Drive, St. Louis, MO, 63141, USA

Keywords:
Pollen load and diversity
museum specimens
phenology changes.

Presentation Type: Symposium Presentation
Session: SY08, Studying plant pollinator interactions in changing environments: approaches, lessons and future directions
Location: Chatham Ballroom - C/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 2:15 PM
Number: SY08003
Abstract ID:440
Candidate for Awards:None