The genetic implications of translocations on Fisher (Pekania pennanti) populations in Montana and Idaho

Abstract

Translocations are the intentional movement of animals across landscapes for conservation purposes and are used as a common method for restoring populations. Fisher (Pekania pennanti) populations have been extensively reintroduced and augmented in the Western United States, often using multiple source populations. To date, little is known about the success of past translocation efforts for Fisher recovery in the West, nor what the effects of using distinct populations for translocations were on contemporary population composition and genetic diversity. To understand the effects of historic translocations on contemporary Fisher population recovery, we analyzed >34 years of genetic data from fishers in Idaho and Montana (n = 315) that received multiple translocations from divergent source populations. We observed high genetic differentiation between fishers descendant from translocations using source populations in the Midwestern United States and translocated to the Cabinet Mountain range (MID) and fishers sampled throughout the rest of Idaho and Montana. Fishers outside of the Cabinet Mountains exhibited little genetic structure and had endemic US Northern Rocky Mountain or British Columbia mitochondrial haplotypes (BC-CLR), consistent with remnant populations that persisted in Montana and Idaho, intermixed with mid-20th century translocations of British Columbia populations. Five fishers had a low probability of nuclear genetic assignment to either the MID or the BC-CLR genetic clusters but showed evidence of recently derived British Columbia genetic ancestry. MID and BC-CLR genetic clusters in the US Northern Rocky Mountains had similar levels of genetic diversity across time and space but exhibited no evidence of gene flow between them. This pattern suggests that while translocation efforts succeeded in creating Fisher populations that persisted on the landscape, they have not created enough propagule pressure to produce movement between populations.

Citation

Fraik, Alexandra K.; Pilgrim, Kristine L.; Mosby, Cory E.; Weir, Richard; Heusser, Cameron L.; Kluge, Nathan; Schwartz, Michael K. 2025. The genetic implications of translocations on Fisher (Pekania pennanti) populations in Montana and Idaho. Journal of Mammalogy. 106: 1311-1323.