Amphibians are considered the most threatened class of vertebrates on earth and conservation effort in recent years has been focusing on monitoring spatial distributions and determining status and health of amphibian populations. As many of the critically endangered amphibians are highly elusive species, monitoring them can be an arduous task. This often leads to uncertainty about the species occurrence and hence results in ineffective conservation action. The recently rediscovered Hula painted frog (Latonia nigriventer) has not been seen for many decades, and was therefore categorized extinct. Since its rediscovery in 2011, individuals from the critically endangered species have been found, with great effort, only in four restricted sites. In order to conduct a comprehensive study on this rare species, monitoring its distribution is of high importance. We applied the emerging molecular-ecological approach of environmental DNA (eDNA) to search for new populations of the Hula painted frog in aquatic habitats. We further used the eDNA data to classify the landscape factors associated with the species distribution and to predict its suitable habitats. We sampled 52 aquatic sites in the Hula valley during the spring of 2015 and 2016 by water filtering, and amplified the samples with a species-specific qPCR assay.
Results/Conclusions
DNA of the Hula painted frog was detected in 22 of the sites, all of which clustered within three areas in the Hula valley. As all three areas are protected areas, these findings highlight the important role of nature reserves and nature parks for the conservation of this rare amphibian in particular, and for wildlife conservation in general. A boosting classification model showed that soil type, vegetation cover, and the current and former habitats are all key predictors of the frog's current distribution. Intriguingly, the habitat suitability models reveal a high affinity of the species to its long-lost habitat of the historical wetlands. Our findings encourage a series of informed searches for new populations of one for the most endangered vertebrates on earth, and provide guidance for future conservation management programs. Our results demonstrate the use of eDNA approaches and distribution modelling to delineate the current distribution and suitable habitats of rare and elusive species. In the era of global conservation crisis of amphibians, developing the eDNA approach, that might be the only feasible method for a reliable detection for many critically endangered and elusive amphibians, is of particularly importance.