Abstract Detail


Waters, Christopher [1], Krosnick, Shawn [2].

Documenting effective pollinator species and metabarcoding environmental DNA to monitor pollinator communities across the range of Physaria globosa (Brassicaceae).

Physaria globosa (Desv.) O’Kane & Al-Shahbaz (Brassicaceae) was federally listed as endangered on 1 August 2014. Also known as Short’s bladderpod, P. globosa can be found in 33 extant populations across middle Tennessee, central Kentucky, and southern Indiana. Little is currently known regarding the life history, reproduction, and threats to P. globosa. There has been one previous study that investigated the pollination ecology of P. globosa that found six effective pollinator species in one population in Trousdale County, Tennessee. Contrary to other species of Physaria in western North America, this previous study also suggested P. globosa is primarily pollinated by syrphid flies. Pollinator communities are likely to be more diverse across the range of P. globosa and will likely be primarily pollinated by halictid bees. This research is part of ongoing recovery and conservation efforts to document effective pollinator species across the range of P. globosa and establish long-term monitoring protocols for these pollinator communities via the metabarcoding of pollinator environmental DNA (eDNA). During foraging, insects can leave behind fragments of DNA in the form of saliva, shed hairs, or other excretions that can be extracted, amplified, and identified to species using “barcode genes.” Barcode gene are variable across taxa but conserved within taxa allowing for identification of unknown sequences. Floral visitors were collected from five populations of P. globosa in spring of 2021 and 2022 representing each EPA level IV ecoregion where it is known to exist. Pollen was removed from floral visitors using an ethyl acetate wash and stained with fuchsin in glycerol to classify and identify effective pollinator species. Physaria pollen has a pentacolpate shape making it morphologically unique when compared to other cohabiting angiosperms. Preliminary results indicate the primary pollinators of P. globosa are solitary ground-nesting bees, which is more similar to other Physaria species. A reference database of gene sequences for pollinator species is under construction using two mitochondrial loci that will be used to cross reference unknown pollinator eDNA sequences extracted from openly pollinated P. globosa flowers. Insect eDNA was extracted from P. globosa flowers, separating the pistil from the rest of the flower to differentiate potential pollinators from general floral visitors that did not make contact with the pistil. Initial assays have had success isolating and sequencing insect eDNA extracted from P. globosa pistils. The techniques developed as part of this research could be used for range-wide long-term monitoring of P. globosa pollinator communities and the methods could be adapted for other rare plant species in the future.

1 - Tennessee Technological University, Environmental Studies, 200 W 10th Street , P.O. Box 5152, Cookeville, TN, 38505, United States
2 - Tennessee Tech University, Dept. Of Biology, 1100 East Dixie Avenue, Pennebaker Hall #207, Cookeville, TN, 38505, United States

endangered species
Environmental DNA

Presentation Type: Oral Paper
Number: EC11001
Abstract ID:353
Candidate for Awards:Ecological Section Best Graduate Student Paper

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