Assessment of spatial genetic structure to identify populations at risk for infection of an emerging epizootic disease

• Published in: Ecology and evolution Vol. 10; no. 9; pp. 3977 - 3990
• Main Authors: Miller, William L., Miller‐Butterworth, Cassandra M., Diefenbach, Duane R., Walter, W. David
• Format: Journal Article
• Language: English
• Published: Bognor Regis John Wiley & Sons, Inc 01.05.2020; John Wiley and Sons Inc; Wiley
• Subjects: Algorithms; At risk populations; Chronic wasting disease; Clustering; Corridors; Deer; Differentiation; Disease control; disease spread; Disease transmission; Gene flow; Genetic analysis; Genetic structure; Genotypes; Health risks; hierarchical genetic structure; Identification methods; Landscape; landscape genetics; Mitigation; Odocoileus virginianus; Original Research; Permeability; Pest outbreaks; Population genetics; Population structure; Populations; Subpopulations; Substructures; Topography; Traffic volume; Transmissible spongiform encephalopathy; white‐tailed deer; Wildlife; Wildlife management; United States > US; North America; Maryland; Virginia; Pennsylvania
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6161

Understanding the geographic extent and connectivity of wildlife populations can provide important insights into the management of disease outbreaks but defining patterns of population structure is difficult for widely distributed species. Landscape genetic analyses are powerful methods for identifying cryptic structure and movement patterns that may be associated with spatial epizootic patterns in such cases. We characterized patterns of population substructure and connectivity using microsatellite genotypes from 2,222 white‐tailed deer (Odocoileus virginianus) in the Mid‐Atlantic region of the United States, a region where chronic wasting disease was first detected in 2009. The goal of this study was to evaluate the juxtaposition between population structure, landscape features that influence gene flow, and current disease management units. Clustering analyses identified four to five subpopulations in this region, the edges of which corresponded to ecophysiographic provinces. Subpopulations were further partitioned into 11 clusters with subtle (FST ≤ 0.041), but significant genetic differentiation. Genetic differentiation was lower and migration rates were higher among neighboring genetic clusters, indicating an underlying genetic cline. Genetic discontinuities were associated with topographic barriers, however. Resistance surface modeling indicated that gene flow was diffuse in homogenous landscapes, but the direction and extent of gene flow were influenced by forest cover, traffic volume, and elevational relief in subregions heterogeneous for these landscape features. Chronic wasting disease primarily occurred among genetic clusters within a single subpopulation and along corridors of high landscape connectivity. These results may suggest a possible correlation between population substructure, landscape connectivity, and the occurrence of diseases for widespread species. Considering these factors may be useful in delineating effective management units, although only the largest features produced appreciable differences in subpopulation structure. Disease mitigation strategies implemented at the scale of ecophysiographic provinces are likely to be more effective than those implemented at finer scales. We characterized the spatial population structure of white‐tailed deer in the Mid‐Atlantic region of the United States in order to evaluate the juxtaposition population structure, gene flow patterns, and chronic wasting disease cases in the region. We found evidence of four to five subpopulation units, the extents of which generally corresponded with ecophysiographic provinces, with 11 subtle genetic clusters nested hierarchically within subpopulation units. Landscape genetic analyses revealed corridors of high connectivity adjacent to ridges, roads, and open areas, which may indicate directed disease transmission in regions heterogeneous for these features.