Habitat selection and genetic diversity of a reintroduced ‘refugee species’

Abstract

A ‘refugee’ species is one with a current distribution that has been restricted to a subset of their former niche by threatening processes. Conservation opportunities for such species can be limited by a poor understanding of habitat requirements, where habitat models are based on current distributions and not the innate capacity of the animal to survive where threats are managed. We examined patterns of habitat selection by a putative refugee species, the threatened New Holland mouse Pseudomys novaehollandiae, following reintroduction into historic habitat (habitat that corresponds to a currently unoccupied component of its former niche). Current New Holland mouse populations exist predominantly in coastal heath habitat of select vegetation and fire history, and these environmental conditions differ greatly to those found across the species historical distribution. Using a novel, non‐invasive method of detection for the species, we investigated patterns of habitat selection following reintroduction into historic habitat, where the species primary threat of exotic predators has been removed. We also assessed the changes in genetic diversity measures across three stages of the reintroduction process (before, during and after) using microsatellite markers, to reflect on past efforts in maintaining genetic diversity. We found that historic habitat can still support New Holland mouse populations and identified more diverse potential habitat for the species. We also identified loss of alleles and an increased inbreeding coefficient at the captive breeding stage, but these findings were not statistically significant. This study expands on our limited understanding of habitat requirements and the fundamental niche of the New Holland mouse, highlighting new potential conservation opportunities.

Population genomics and conservation management of the threatened black-footed tree-rat (Mesembriomys gouldii) in northern Australia

“…Conservation actions that may benefit the black-footed tree-rat include targeted early season prescribed burning, to prevent high-intensity late dry season fires that reduce habitat integrity (e.g., retention of hollow bearing and fruiting shrubs), and greater retention of old growth vegetation (i.e., 4 years at unburnt) in close proximity to known populations (von Takach et al 2020 a, 2020 b; Radford et al 2021 ; von Takach et al 2022 ). Conserving genetic diversity in a captive breeding program could also be pursued, as has been done for other Australian rodents (Lambert et al 2016 ; Abicair et al 2020 ), to supplement wild populations with captive-reared individuals or act as an insurance population. While there is one such program for black-footed tree-rats in the Northern Territory, its geographic focus is on the Darwin region, and a broader program could be established that incorporates the knowledge of multiple evolutionary lineages and our understanding of their geographic spread and genomic diversity.…”

Analyzing captive breeding outcomes to inform reintroduction practice: lessons from the pookila (Pseudomys novaehollandiae)

“…Reintroductions are a priority for the conservation of the pookila because it is currently vulnerable and experiencing a fragmented and decreasing population ( Woinarski and Burbidge 2016 ; Wilson et al 2018 ; Lazenby et al 2019 ; Burns 2020 ). Research surrounding previous reintroductions of the pookila has included: trials of soft-release enclosures and monitoring techniques ( Wilson et al 2003 , 2018 ); an examination of habitat selection and changes in the genetic diversity of pookila through the reintroduction process ( Abicair et al 2020 ); and the development of “Mini Safe Havens” (i.e., permanent semipermeable refuge areas) to facilitate the in situ learning and adaptation of pookila to coexist with key threats ( Smith et al 2022 ). Experimental translocations have also been undertaken to examine the recolonization of regenerating habitat by pookila, and the potential for competition with the introduced house mouse (i.e., laboratory mouse, Mus musculus ; Fox and Pople 1984 ; Fox and Twigg 1991 ).…”