Abstract
Sclerolaena napiformis is a perennial chenopod endemic to southeast Australia. Human-mediated habitat loss and fragmentation over the past century has caused a rapid decline in abundance and exacerbated reduced connectivity between remnant populations across three disjunct regions. To assess conservation requirements, we measured the genetic structure of 27 populations using double digest RADseq). We combined our genetic data with habitat models under projected climate scenarios to identify changes in future habitat suitability. There was evidence of regional differentiation that may pre-date (but also may be compounded) by recent habitat fragmentation. We also found significant correlation between genetic and geographic distance when comparing sites across regions. Overall, S. napiformis showed low genetic diversity and a relatively high proportion of inbreeding/selfing. Climate modelling, based on current occupancy, predicts a reduction in suitable habitat for S. napiformis under the most conservative climate change scenario. We suggest that the best conservation approach is to maximise genetic variation across the entire species range to allow dynamic evolutionary processes to proceed. We recommend a conservation strategy that encourages mixing of germplasm within regions and permits mixed provenancing across regions to maximise genetic novelty. This will facilitate shifts in genetic composition driven by individual plant fitness in response to the novel environmental conditions this species will experience over the next 50 years.
Highlights
The International Union for the Conservation of Nature (IUCN) recently listed >1250 Australian species as being vulnerable to extinction, which places the risk to Australia’s biodiversity as amongst the highest globally [1]
Genetic factors are not used for IUCN listings, but their inclusion can improve the assessment of extinction risk and subsequent conservation of some species [2]
We suggest that conservation management of S. napiformis utilises the genetic diversity found in all populations from the northeast, central, and southwest to maximise the adaptability of the species in increasingly novel environments
Summary
The International Union for the Conservation of Nature (IUCN) recently listed >1250 Australian species as being vulnerable to extinction, which places the risk to Australia’s biodiversity as amongst the highest globally [1]. Genetic factors are not used for IUCN listings, but their inclusion can improve the assessment of extinction risk and subsequent conservation of some species [2]. Reproductive strategies, including the breeding system and dispersal capacity of pollen and seed, influence the distribution of genetic diversity, which can have a strong effect on plant population fitness [8]. Predictions of increased aridity and shifting seasonality compound the effects of recent human-mediated changes to their habitat [9]. These factors combine to escalate the extinction risk of threatened species by reducing habitat connectivity, thereby disrupting
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