Abstract
BackgroundAs increasingly fragmented and isolated populations of threatened species become subjected to climate change, invasive species and other stressors, there is an urgent need to consider adaptive potential when making conservation decisions rather than focussing on past processes. In many cases, populations identified as unique and currently managed separately suffer increased risk of extinction through demographic and genetic processes. Other populations currently not at risk are likely to be on a trajectory where declines in population size and fitness soon appear inevitable.ResultsUsing datasets from natural Australian mammal populations, we show that drift processes are likely to be driving uniqueness in populations of many threatened species as a result of small population size and fragmentation. Conserving and managing such remnant populations separately will therefore often decrease their adaptive potential and increase species extinction risk.ConclusionsThese results highlight the need for a paradigm shift in conservation biology practise; strategies need to focus on the preservation of genetic diversity at the species level, rather than population, subspecies or evolutionary significant unit. The introduction of new genetic variants into populations through in situ translocation needs to be considered more broadly in conservation programs as a way of decreasing extinction risk by increasing neutral genetic diversity which may increase the adaptive potential of populations if adaptive variation is also increased.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-016-0163-z) contains supplementary material, which is available to authorized users.
Highlights
As increasingly fragmented and isolated populations of threatened species become subjected to climate change, invasive species and other stressors, there is an urgent need to consider adaptive potential when making conservation decisions rather than focussing on past processes
We show using neutral marker genetic datasets from five Australian mammals that random genetic drift is likely to be responsible for the uniqueness of populations of many threatened taxa; by managing such populations as subspecies, Evolutionarily Significant Unit (ESU) and/or management unit (MU), the extinction risk of the entire species is likely to be increased based on genetic grounds
All species are listed under the Australian Environment Protection and Biodiversity Conservation (EPBC) Act 1999 or International Union for Conservation of Nature (IUCN), are considered to be in a state of decline, and consist of populations that have been given the status of subspecies (D. maculatus, P. gunnii), ESUs (B. parvus, D. hallucatus, D. maculatus) and MUs (B. parvus, D. hallucatus, D. maculatus, D. viverrinus) (Table 1)
Summary
As increasingly fragmented and isolated populations of threatened species become subjected to climate change, invasive species and other stressors, there is an urgent need to consider adaptive potential when making conservation decisions rather than focussing on past processes. The advent of molecular techniques, led to ESUs being largely defined by neutral genetic markers (e.g., monophyly at mitochondrial markers [10]), with further delineation of populations into Management Units (MUs) depending on the degree of differentiation at nuclear loci [10, 13]. This provided a routine way of characterising unique populations, and has gained widespread use in conservation despite the focus being on relatively few neutral genetic markers
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