Genetic monitoring of the greater stick-nest rat meta-population for strategic supplementation planning

Lauren C White,Laura Ruykys,Kym Ottewell,Katherine E Moseby,John Kanowski,Peter Copley,Vicki A Thomson,Rebecca West,Jeremy J Austin,Margaret Byrne,Stephen C Donnellan

doi:10.1007/s10592-020-01299-x

Abstract

Translocation is an increasingly common component of species conservation efforts. However, translocated populations often suffer from loss of genetic diversity and increased inbreeding, and thus may require active management to establish gene flow across isolated populations. Assisted gene flow can be laborious and costly, so recipient and source populations should be carefully chosen to maximise genetic diversity outcomes. The greater stick-nest rat (GSNR, Leporillus conditor), a threatened Australian rodent, has been the focus of a translocation program since 1985, resulting in five extant translocated populations (St Peter Island, Reevesby Island, Arid Recovery, Salutation Island and Mt Gibson), all derived from a remnant wild population on the East and West Franklin Islands. We evaluated the genetic diversity in all extant GSNR populations using a large single nucleotide polymorphism dataset with the explicit purpose of informing future translocation planning. Our results show varying levels of genetic divergence, inbreeding and loss of genetic diversity in all translocated populations relative to the remnant source on the Franklin Islands. All translocated populations would benefit from supplementation to increase genetic diversity, but two—Salutation Island and Mt Gibson—are of highest priority. We recommend a targeted admixture approach, in which animals for supplementation are sourced from populations that have low relatedness to the recipient population. Subject to assessment of contemporary genetic diversity, St Peter Island and Arid Recovery are the most appropriate source populations for genetic supplementation. Our study demonstrates an effective use of genetic surveys for data-driven management of threatened species.

Highlights

Conservation and recovery actions for threatened animal species increasingly involve the establishment of translocated populations (Weeks et al 2011)
In the interest of prioritization, two populations in particular stand out as candidates for supplementation in the immediate future based on their within-population genetic R, estimated Ne, divergence from the source population, and difference in genetic diversity and inbreeding compared to the Franklin Islands
For the other translocated populations that we have not identified as priorities but that would benefit from supplementation, we suggest the most appropriate sources are those that have the lowest between-population genetic R and/or highest divergence as measured by FST when compared to the recipient population (Table 3)

Summary

Introduction

Conservation and recovery actions for threatened animal species increasingly involve the establishment of translocated populations (Weeks et al 2011) Such populations can increase a species’ total population size and geographic range, and thereby guard against extinction (Frankham et al 2017). Establishing gene flow between isolated populations through supplementation ( termed ‘reinforcement’) can improve or maintain the genetic diversity of small populations (Margan et al 1998) This has been demonstrated in species such as the alpine ibex (Capra ibex; Biebach and Keller 2012), boodie (Bettongia lesueur; Thavornkanlapachai et al 2019), mountain pygmy possum (Burramys parvus; Weeks et al 2017), Florida panther (Puma concolor coryi; Pimm et al 2006) and Tasmanian devil (Sarcophilus harrisii, McLennan et al 2020). To support decisions by conservation practitioners, genetic monitoring can be used to assess whether supplementation is warranted (Schwartz, et al 2007)

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