An environmental DNA (eDNA) study of pollinator biodiversity along an urban-to-rural gradient

Pollinators are keystone organisms that provide numerous benefits to ecosystems. Approximately one-third of the global food supply, including around 80% of crop species, relies on pollination services for successful reproduction. Research suggests that wild pollinator populations have declined due to factors such as climate change, pesticide use, and increasing urbanization. As cities expand and natural landscapes transform into urban spaces, it is imperative to comprehensively understand the ecological impact of these changes on pollinator biodiversity. This research investigates the influence of urbanization on pollinator biodiversity within The Saginaw Bay Area, a region that has undergone significant demographic changes over recent decades. Environmental DNA (eDNA) analysis will assess four collection sites representing varying urbanization levels along an Urban-to-Rural continuum (Natural, Rural, Urban-Rural, Suburban, and Urban environments), with an additional collection site in an undisturbed natural habitat. The flowerheads of the common dandelion were identified as the best indicator of pollinator diversity for this study, particularly in paved sampling sites with low floral diversity. Fifty milligrams of the flowerheads were homogenized with CTAB lysis buffer, and total genomic DNA was extracted using the chloroform-phenol separation method. Amplicons of the COI, 16S, and 28S genes were amplified by endpoint PCR using primers with Illumina adaptor regions. Amplicon-based sequences were analyzed using QUIIME, and community diversity analysis was performed using various R packages. Our results shed light on the ecological impact of urbanization on pollinator communities and will inform conservation strategies and biodiversity management amidst urban expansion.