Date of Award





Earth and Space Science - Environmental Science Track


Earth & Space Science

First Advisor

Kevin S. Burgess


Floral visitation resulting in interspecific pollen transfer (IPT) from non-native or invasive plant species can affect the reproductive fitness of native plant species through pollen allelopathy, stigma clogging, stylar clogging, and ovule (seed) discounting. The prevalence of IPT and the importance of pollinators in mediating its impacts, however, remain poorly understood. Although most traditional methods for examining visitor movement are insufficient for determining rates of potential IPT, one promising alternative is the use of DNA barcoding. Because floral visitors eat, collect or unknowingly obtain pollen, nectar and other floral tissues, plant DNA should be recoverable from their bodies, permitting molecular identification of pollen loads. To assess the utility of plant DNA barcodes for tracking floral visitation, I collected 89 honeybees (Apis mellifera) and 49 bumblebees (Bombus spp.) from a disturbed forest edge in Columbus, Georgia and analyzed their pollen loads using the plastid DNA barcode region rbcL. The identities of monospecific pollen loads were determined by comparing sequences to a local plant reference library containing 22 native and 27 non- native plant species. The overall recovery of rbcL sequences from pollen loads was relatively high (41.6%). Based on local BLASTn analysis, 95% of monospecific pollen loads were identifiable to the species level. Rates of heterospecific visitation were quite high (77%), as indicated by pure heterospecific (15%) and mixed pollen loads (62%). Collectively, these results indicate that 1) plant DNA barcode sequences can be recovered from pollen loads; 2) species-level identification of pollen loads can be determined with high accuracy; and 3) levels of heterospecific visitation and potential IPT can be assessed with DNA barcoding. As a new means of rapidly and effectively detecting potential pollen transfer between plant species that share floral visitors, my study demonstrates that DNA barcode analysis of pollen loads will contribute greatly to the rapidly growing field of ecological barcoding.