Predators and genetic fitness: key threatening factors for the conservation of a bettong species

Abstract

Globally, many wildlife species are declining and an increasing number are threatened by extinction or are extinct. Active management is generally required to mitigate these trends and population viability analysis (PVA) enables different scenarios to be evaluated and informs management decisions. Based on population parameters obtained from a threatened bettong, the woylie (Bettongia penicillata ogilbyi), we developed and validated a PVA model. We identified the demographic and genetic responses to different threatening factors and developed a general framework that would facilitate similar work in other bettong species. The two main threatening processes are predation by introduced animals and its interaction with reduced fitness (e.g. due to inbreeding depression or a disease). Although predation alone can drive a decline in certain circumstances (e.g. when predation success is independent from prey population density), synergistically, predation and reduced fitness can be particularly relevant, especially for small populations. The minimum viable population size was estimated at 1000–2000 individuals. In addition, the models identified that research into age-specific mortality rates and predation rates by introduced animals should be the focus of future work. The PVA model created here provides a basis to investigate threatening processes and management strategies in woylie populations and other extant bettong species, given the ecological and physiological similarities among these threatened species.