The Invasive Bank Vole (Myodes glareolus): A Model System for Studying Parasites and Ecoimmunology during a Biological Invasion

Remotely sensed localised primary production anomalies predict the burden and community structure of infection in long-term rodent datasets

The increasing frequency and cost of zoonotic disease emergence due to global change have led to calls for the primary surveillance of wildlife. This should be facilitated by the ready availability of remotely sensed environmental data, given the importance of the environment in determining infectious disease dynamics. However, there has been little evaluation of the temporal predictiveness of remotely sensed environmental data for infection reservoirs in vertebrate hosts due to a deficit of corresponding high-quality long-term infection datasets. Here we employ two unique decade-spanning datasets for assemblages of infectious agents, including zoonotic agents, in rodents in stable habitats. Such stable habitats are important, as they provide the baseline sets of pathogens for the interactions within degrading habitats that have been identified as hotspots for zoonotic emergence. We focus on the enhanced vegetation index (EVI), a measure of vegetation greening that equates to primary productivity, reasoning that this would modulate infectious agent populations via trophic cascades determining host population density or immunocompetence. We found that EVI, in analyses with data standardised by site, inversely predicted more than one-third of the variation in an index of infectious agent total abundance. Moreover, in bipartite host occupancy networks, weighted network statistics (connectance and modularity) were linked to total abundance and were also predicted by EVI. Infectious agent abundance and, perhaps, community structure are likely to influence infection risk and, in turn, the probability of transboundary emergence. Thus, the present results, which were consistent in disparate forest and desert systems, provide proof-of-principle that within-site fluctuations in satellite-derived greenness indices can furnish useful forecasting that could focus primary surveillance. In relation to the well-documented global greening trend of recent decades, the present results predict declining infection burden in wild vertebrates in stable habitats; but if greening trends were to be reversed, this might magnify the already upwards trend in zoonotic emergence.

The Bank Vole (Clethrionomys glareolus) as a Model System for Adaptive Phylogeography in the European Theater

The legacy of climatic changes during the Pleistocene glaciations allows inferences to be made about the patterns and processes associated with range expansion/colonization, including evolutionary adaptation. With the increasing availability of population genomic data, we have the opportunity to examine these questions in detail and in a variety of non-traditional model species. As an exemplar, here we review more than two decades of work by our group and others that illustrate the potential of a single “non-model model” mammal species - the bank vole (Clethrionomys glareolus), which is particularly well suited to illustrate the complexities that may be associated with range expansion and the power of genomics (and other datasets) to uncover them. We first summarize early phylogeographic work using mitochondrial DNA and then describe new phylogeographic insights gained from population genomic analysis of genome-wide SNP data to highlight the bank vole as one of the most compelling examples of a forest mammal, that survived in cryptic extra-Mediterranean (“northern”) glacial refugia in Europe, and as one of the species in which substantial replacement and mixing of lineages originating from different refugia occurred during end-glacial colonization. Our studies of bank vole hemoglobin structure and function, as well as our recent ecological niche modeling study examining differences among bank vole lineages, led us to develop the idea of “adaptive phylogeography.” This is what we call the study of the role of adaptive differences among populations in shaping phylogeographic patterns. Adaptive phylogeography provides a link between past population history and adaptation that can ultimately help predict the potential of future species responses to climate change. Because the bank vole is part of a community of organisms whose range has repeatedly contracted and then expanded in the past, what we learn from the bank vole will be useful for our understanding of a broad range of species.