Evaluating the legacy of multiple introductions of American martens on spatiotemporal patterns of genetic diversity

Abstract

Species reintroductions are successful when established populations maintain both demographic stability and genetic diversity. Such a result may be obtained by ensuring both structural habitat connectivity and genetic connectivity among reintroduced and remnant populations. Nevertheless, prezygotic barriers such as assortative mating can prevent the flow of genetic material between populations, even when migration between populations is high. Limited gene flow may be particularly relevant for reintroductions that were sourced either from captive-bred populations or from disparate locations in the wild. American martens (Martes americana) have been reintroduced repeatedly in the Upper Midwestern United States in an effort to establish self-sustaining populations. We quantified levels of genetic diversity within and spatial genetic variance among four marten populations during two time periods separated by 10 years. Spatially informed and naïve discriminant analysis of principal components were used to assign individuals to populations. Results indicate that heterozygosity declined and inbreeding coefficients increased between the two collection periods, while genetic structure among populations also increased. Data are consistent with assortative mating contributing to reapportioning of genetic variation. Population assignment tests show that migration among populations is apparent, but admixture (based on cluster membership probabilities) is low and declined over time. Specifically, martens may be successfully dispersing between populations but a lack of admixture indicates a lack of reproductive contributions to genetic diversity by migrants. Because marten reintroductions in this region are well-documented and well-monitored, lessons can be derived from results to inform future reintroductions. We encourage a careful balance of supplementing genetic diversity via augmentation while avoiding translocation of animals from disparate populations that may result in reproductive isolation of migrants. In combination with the maintenance of a functionally connected landscape, this strategy would maximize the likelihood of a successful reintroduction in terms both of demography and genetics.

Conservation of rare and cryptic species: Challenges of uncertainty and opportunities for progress

“…showing the central challenge in our case study with Humboldt martens: data insufficiency. Within this manuscript, we describe several approaches to addressing data insufficiency that can lead to a diversity of beneficial outcomes, thereby advancing conservation of rare and cryptic species implement non-invasive genetic techniques with other approaches (e.g., camera traps) have greatly improved understanding of American marten (M. americana) abundance, distribution, and population viability in the Great Lakes region, offering a precedent of success that could be replicated elsewhere (Day et al, 2022;Manlick et al, 2017;Smith et al, 2021). (Tulloch et al, 2018).…”

“…Contemporary quantitative approaches that allow incorporation of data from different sources can further strengthen inferences and optimize conservation impacts of research (Fidino et al, 2022; Gilbert et al, 2021; Pearson et al, 2006; Stabach et al, 2017). For instance, collaborative and interdisciplinary efforts to implement non‐invasive genetic techniques with other approaches (e.g., camera traps) have greatly improved understanding of American marten ( M. americana ) abundance, distribution, and population viability in the Great Lakes region, offering a precedent of success that could be replicated elsewhere (Day et al, 2022; Manlick et al, 2017; Smith et al, 2021).…”

Preservation of genetic diversity in a highly fragmented population of the gray‐sided vole Myodes rufocanus in an intensive farming region

“…Day et al ( 2022 ) investigated genetic diversity and structure in reintroduced American martens, Martes americana , in Wisconsin, which were sampled during two time periods separated by 10 years. Because migration among populations was apparent but the degree of admixture, estimated based on cluster admixture proportions, was low and declined over time, they inferred that martens successfully dispersed between populations but migrants did not contribute to genetic diversity, likely because of assortative mating (Day et al, 2022 ). In the aforementioned study of gray‐sided voles using two fixed grids, admixture proportions changed differently between the grids (Ishibashi & Takahashi, 2021 ).…”