Contrasting Patterns of Raccoon (Procyon lotor) Spatial Population Genomics Throughout a Rabies Management Area in Eastern North America

Wide-ranging, generalist species provide both interesting and challenging opportunities for research questions focused on population structure. Their continuous distributions and ability to occupy diverse habitat types can obscure genetic signals of ancestry and geographic clustering. However, spatially informed population genetic approaches are notable for high-resolution identification of geographic clusters that often elude more classical clustering models. The northern raccoon (Procyon lotor) is a broadly distributed species in North America, with populations in diverse habitats ranging from dense urban to rural landscapes. Wildlife management agencies have an interest in understanding raccoon ecology, given their propensity for human-wildlife conflicts and zoonotic diseases. We combined samples from an extensive raccoon tissue repository with a RADcapture panel of 1000 microhaplotype loci to conduct spatial genetic analyses of raccoon populations in eastern North America. Our objective was to estimate patterns of genetic diversity on the landscape that may inform raccoon rabies management. Bayesian clustering analyses delineated multiple ancestry clusters that encompassed large areas across 22 US states and 2 Canadian provinces. We discovered a potential phylogeographic split between central and southern samples from those in the northeast region, which correlates with post-Pleistocene recolonization detected in a multitude of species from the region. A finer scale structure was identified using spatially explicit analyses and demonstrated variable dispersal/gene flow patterns within specific regions. The Appalachian Mountain region restricted local connectivity among raccoons, while raccoon populations in central New York, the Ohio River Valley, southern Québec, and southern Alabama demonstrated high genetic connectivity. The results from this study highlight how raccoon ecology and historical biogeography can help contextualize contrasting hypotheses about the influence of landscape on raccoon movement patterns, which can inform management of zoonotic disease risks at regional scales.

Seasonal Variation in Mammalian Mesopredator Spatiotemporal Overlap on a Barrier Island Complex

Due to lack of apex predators in human-dominated landscapes, mesopredator relationships are complex and spatiotemporal niche partitioning strategies can vary, especially when seasonal shifts in resource availability occur. Our objective was to understand spatiotemporal niche overlap across seasons among mesopredators inhabiting a barrier island complex. We placed 19 unbaited cameras throughout Fort De Soto County Park, Florida, USA between February 2021 and July 2023. Of six mesopredator species detected, three species had >75 detections during both the wet and dry seasons (coyote, Canis latrans; Virginia opossum, Didelphis virginiana; and raccoon, Procyon lotor). Using general linear mixed models, we determined that during the wet season coyote-raccoon and raccoon-opossum detections were positively associated with each other (p < 0.05). During the dry season, raccoon-opossum detections were positively associated, and opossums were more likely to be detected around mangroves. After calculating coefficients of overlap, we found all three species varied their temporal activity between seasons. During the dry season exclusively, all three mesopredators occupied different temporal niches. The park's isolated but developed nature has potentially led to a destabilized mesopredator community. Understanding seasonal mesopredator dynamics of Fort De Soto is particularly important because this park supports a high number of nesting shorebirds and sea turtles, which are known food sources for mesopredators.

Microsatellites and mitochondrial evidence of multiple introductions of the invasive raccoon Procyon lotor in France

Raccoons (Procyon lotor) are worldwide invaders, due to deliberate or accidental releases, and their impacts exceed hundred of billions of Euros in Europe only. In France, raccoons have currently established three separate, expanding populations. Identifying the current spatial genetic structure, dispersal events and phylogeography of these populations is needed to infer the invasion history and identify management units. We used wild and captive individuals sampled in France and Belgium to characterize the genetic diversity and current population genetic structure of French raccoon populations and identify potential genetic connectivity with the Belgium population using both mitochondrial DNA and microsatellite loci. Results confirm that French populations are the result of at least three independent introductions. While the three populations display low genetic diversity and sign of recent bottleneck, they are still expanding, suggesting that in addition to their ecological plasticity, the remaining genetic diversity is sufficient to successfully adapt to their new environment and allow a quick colonization. Particular attention must be given to the North-Eastern population, which shows genetic admixture with the Belgium population, as admixed individuals may exhibit hybrid vigor facilitating their expansion. The comparison of captive and wild individuals did not allow to identify a potential captive origin of the wild populations. The current regulation in France allowing captivity in zoos without enforcement to tighten the biosecurity of detention facilities might dampen any management measure as few introduced founders might be enough to create new populations.