Spatial population genetics in heavily managed species: Separating patterns of historical translocation from contemporary gene flow in white-tailed deer

Abstract

Approximately 100 years ago, hunter-harvest eliminated white-tailed deer (WTD; Odocoileus virginianus) in eastern North America, which subsequently served as a catalyst for wildlife management as a national priority. An extensive stock-replenishment effort soon followed, with WTD broadly translocated among states as a means of reestablishment. Now, contemporary issues focus on reverberations from a global (and fatal) epizootic disease in Cervidae (chronic wasting disease, CWD). These cumulative impacts have effectively obscured the traditional signals of post-translocation gene flow and dispersal in North American WTD. To develop baseline data for its adjudication, we applied cutting-edge molecular and biogeographic tools to process 1,143 WTD sampled state-wide in AR, with 54,102 single nucleotide polymorphisms (SNPs) derived via reduced-representation genomic sequencing. We then employed Simpson's diversity index to visualize landscape genetic patterns previously obscured by extensive translocations, and this allowed us to summarize multidimensional ancestry assignments and identify spatio-genetic transitions. We then sub-sampled transects and tested clinal patterns across loci for concordance and/or coincidence. Two salient results emerged: (A) Genetic echoes from historic translocations are widely apparent; and (B) Geographic filters (major rivers; urban centers; highways) now act as inflection points for the distribution of more contemporary ancestry. These results, in synergy, yielded a state-wide assessment of how historic translocations, as well as ongoing processes, have acted to dictate contemporary population structure of Arkansas WTD. In addition, the analytical framework employed herein effectively deciphered the extant/historic drivers of WTD distribution in AR. It is also applicable for other biodiversity elements with demographic histories equally as complex.

Quantifying isolation-by-resistance and connectivity in dendritic ecological networks

“…As with landscape genetic studies, individual movements via extremely rare natural connection or human-mediated translocations will also bias result by altering spatio-genetic associations (Chafin et al, 2021). However, these occurrences could potentially be adjusted for by adding additional edges as historic connections, under the assumption that a priori hypotheses can be formulated.…”