Davis, M. A. | Search bioRxiv

bioRxiv2021

BeeDNA: microfluidic environmental DNA metabarcoding as a tool for connecting plant and pollinator communities

Pollinators are imperiled by global declines that can reduce plant reproduction, erode essential ecosystem services and resilience, and drive economic losses. Monitoring pollinator biodiversity trends is key for adaptive conservation and management, but conventional surveys are often costly, time consuming, and require taxonomic expertise. Environmental DNA (eDNA) metabarcoding surveys are booming due to their rapidity, non-invasiveness, and cost efficiency. Microfluidic technology allows multiple primer sets from different markers to be used in eDNA metabarcoding for more comprehensive species inventories whilst minimizing biases associated with individual primer sets. We evaluated microfluidic eDNA metabarcoding for pollinator community monitoring by introducing a bumblebee colony to a greenhouse flower assemblage and sampling natural flower plots. We collected nectar draws, flower swabs, or whole flower heads from four flowering species, including two occurring in both the greenhouse and field. Samples were processed using two eDNA isolation protocols before amplification with 15 primer sets for two markers (COI and 16S). Microfluidic eDNA metabarcoding detected the target bumblebee and greenhouse insects as well as common regional arthropods. Pollinator detection was maximized using whole flower heads preserved in ATL buffer and extracted with a modified Qiagen(R) DNeasy protocol for amplification with COI primers. eDNA surveillance could enhance pollinator assessment by detecting protected and endangered species and being more applicable to remote, inaccessible locations, whilst reducing survey time, effort, and expense. Microfluidic eDNA metabarcoding requires optimization to address remaining efficacy concerns but this approach shows potential in revealing complex networks underpinning critical ecosystem functions and services, enabling more accurate assessments of ecosystem resilience.

ecology↗

bioRxiv2020

Metapopulation Connectivity in Voles (Microtus sp.) as a Gauge for Tallgrass Prairie Restoration in Midwestern North America

Applying quantifiable metrics to validate the success of restoration efforts is crucial for ongoing management programs in anthropogenically fragmented habitats. Estimates of dispersal can provide such baseline data because they measure not only the extent to which restored patches are colonized and interconnected, but also their metapopulation source/sink dynamics. In this context, we estimated dispersal and population connectivity among prairie (Microtus ochrogaster; N=231) and meadow vole (M. pennsylvanicus; N=83), sampled from eight restored plots at five tallgrass prairie sites embedded within the agricultural matrix of midwestern North America. Our expectation was that extensive distances separating these restored habitats (i.e., 48-246 km) would spatially isolate vole metapopulations, resulting in significant genetic differentiation. We first used molecular taxonomy to validate the field-identifications of all sampled individuals, then used pairwise FST derived from 15 microsatellite DNA loci to estimate genetic connectivity among the species-delimited study populations. Metapopulation stability was gauged by assessing migration rates and deriving effective population sizes (Ne). We also calculated relatedness values (r) as a potential surrogate for contact in prairie vole, a primary vector for Lyme disease. Molecular species-assignments contravened field-identifications in 25% of samples (11 prairie/67 meadow) and identified two instances of species-hybridization (0.6%). Local effects (i.e., population crash/drought) were manifested at two sites, as documented by significant temporal declines in Ne and r. Overall, high migration rates and non-significant (10/15) pairwise FST values underscored elevated metapopulation connectivity. A single site that recorded five significant FST values also displayed significant r-values indicating the inadvertent sampling of closely related individuals. This highlights the close social groupings among cooperatively-breeding prairie vole that can exacerbate Lyme disease transmission. Thus, while elevated population connectivity aligns with prairie restoration goals, it also reinforces a need in adaptive management to evaluate environmental matrices for their permeability to vector-borne diseases.

ecology↗