Genetic-based conservation status indicators applied to endemics with restricted distributions: a case for eastern Amazonian cangas plants.

Abstract

Background and aims: Critical analyses of genetic data are essential to assessing population and species' conservation status and establishing strategies for their protection, which include best monitoring and management practices. This is especially crucial for endemic species with restricted distribution ranges.

Methods: We used genomic data to evaluate the efficacy of Kunming-Montreal Global Biodiversity Framework (GBF) genetic indicators in assessing the conservation status of three endemic plants to the ironstone outcrops (cangas) from Amazon: Carajasia cangae, Parapiqueria cavalcantei, and Ipomoea cavalcantei. We also simulated population bottlenecks to estimate potential effects of future habitat fragmentation.

Key results: : Carajasia cangae and P. cavalcantei exhibited low effective population sizes (NE), low genetic diversity, and high inbreeding. Simulations indicated a decrease in genetic diversity and an increase in inbreeding within decades triggered by NE decline. Conversely, I. cavalcantei retains larger NE, greater genetic diversity, and low inbreeding, and demands attention relative to the maintenance of the two genetically distinct populations. Parameters estimated for C. cangae and P. cavalcantei likely reflect their higher self-reproduction rates as opposed to I. cavalcantei, which is self-incompatible. We highlight some problems regarding the application of GBF genetic indicators to predominantly selfing species, such as the fact that their ratio of effective to census population size is far lower than 10% (the usual threshold to obtain NE when genetic data is unavailable) and their NE often falls below the threshold of 500 to maintain the species long-term evolutionary potential.

Conclusions: We suggest that the reproductive system of endemic plants should be considered to refine guidelines and improve the application of genetic indicators, such as a more appropriate minimum NE and group-specific ratios of effective to census population size. Applying these constraints to GBF indicators may also be appropriate to other organisms with similar biology, independent of their levels of endemism.