Measuring connectivity of invasive stoat populations to inform conservation management

Abstract

Context Effective design of conservation management programs for long-term population control requires an accurate definition of the spatial extent of populations, along with a proper understanding of the ways that landscape patchiness influences demography and dispersal within these populations. Aims In the present study, genetic techniques are used to describe the population genetic structure and connectivity of invasive stoats (Mustela erminea) across the Auckland region, New Zealand, so as to assist planning for mainland stoat control, and define potential future eradication units. Methods A sample of stoats from across the region (n = 120), was genotyped at 17 microsatellite loci, and a combination of clustering, genetic population assignment and various migration estimation methods were applied to these data. Key results Moderate population structure was observed (FST = 0.03–0.21), with five geographic populations defined by genetic clustering. Almost all individuals were correctly assigned to the location of origin, and recent migration rates among forest patches were found to be low. Conclusions It is possible to define the origin of stoats at this regional scale using genetic measures. From this, we show that the stoat incursion on Rangitoto Island that occurred post-eradication in 2010 probably came from East Auckland (P < 0.0001), whereas the 2014 stoat incursion on Motutapu Island probably originated from a population linked to the Waitakeres. Also, the Waiheke Island stoat population has minimal connection to all other populations and it is therefore a potential eradication unit. Implications The low migration rates among forest patches indicated that if thorough control is imposed on a discrete forest patch, reinvasion from other forest patches will be relatively low. Importantly, for stoat control in the region, the isolation of the Waiheke Island stoat population means that eradication here is likely to be feasible with low reinvasion pressure.

Delineating genetic management units of sambar deer (

“…Genetic data can be used to delineate population boundaries and assess connectivity between groups (Fraser et al 2013). Investigating the genetic structure of animal populations, to identify individual management units, has previously been used to direct and improve eradication efforts for invasive species, including mink (Neovision vison), stoats (Mustela erminea) and feral pigs (Sus scrofa) (Hampton et al 2004b;Veale et al 2014;Mora et al 2018). Small populations, with clear boundaries and no connectivity, represent the best opportunity for successful eradication because recruitment from other populations is unlikely to occur (Abdelkrim et al 2005).…”

A DNA toolbox for non-invasive genetic studies of sambar deer (Rusa unicolor)

“…Molecular ecology, where genetic data are used to address ecological questions, is an approach often used to obtain information about invasive species. For example, genetic data have been used widely in New Zealand to inform the management of invasive species including possums (Adams et al 2014), stoats (Veale et al 2014) and rats (Abdelkrim et al 2010). In France and South Georgia, genetic data were used to determine the scale and feasibility of control operations by delineating population boundaries and assessing connectivity between populations of ship rat (Rattus norvegicus) (Abdelkrim et al 2005;Robertson and Gemmell 2004).…”