Conservation implications of genetic structure in the narrowest endemic quillwort from the Eastern Amazon

The quillwort Isoëtes cangae is a critically endangered species occurring in a single lake in Serra dos Carajás, Eastern Amazon. Low genetic diversity and small effective population sizes (N _e) are expected for narrow endemic species (NES). Conservation biology studies centered in a single species show some limitations, but they are still useful considering the limited time and resources available for protection of species at risk of extinction. Here, we evaluated the genetic diversity, population structure, N _e, and minimum viable population (MVP) of I. cangae to provide information for effective conservation programs. Our analyses were based on 55 individuals collected from the Amendoim Lake and 35,638 neutral SNPs. Our results indicated a single panmictic population, moderate levels of genetic diversity, and N _e in the order of thousands, contrasting the expected for NES. Negative F_IS values were also found, suggesting that I. cangae is not under risk of inbreeding depression. Our findings imply that I. cangae contains enough genetic diversity to ensure evolutionary potential and that all individuals should be treated as one demographic unit. These results provide essential information to optimize ex situ conservation efforts and genetic diversity monitoring, which are currently applied to guide I. cangae conservation plans.     

Genetic diversity and structure of an endangered medicinal plant species (Pilocarpus microphyllus) in eastern Amazon: implications for conservation

Few studies have evaluated the genetic status of medicinal plants exposed to commercial harvesting. Here, we examine the genetic variability of Pilocarpus microphyllus, an endemic and threatened medicinal plant species from the eastern Amazon, across its largest remaining wild population. Popularly known as jaborandi, species of Pilocarpus genus are the unique known natural source of pilocarpine, an alkaloid used to treat glaucoma and xerostomia. However, Populations of P. microphyllus has experienced a severe decline in the last decades. Using RAD sequencing, we identified a total of 5,266 neutral and independent SNPs in 277 individuals collected from the Carajás National Forest (CNF). We quantified genetic diversity and gene flow patterns and estimated the minimum number of individuals necessary to establish a germplasm bank. Our results revealed high genetic diversity and four spatially distinct clusters of P. microphyllus with substantial admixture among them. Geographic distance and temperature dissimilarity were the factors that best explained the relatedness patterns among individuals. Additionally, our findings indicate that at least 40 matrices sampled randomly from each population would be required to conserve genetic diversity in the long term. In short, P. microphyllus showed high levels of genetic diversity and an effective population size (N_E) sufficient to reduce the likelihood of extinction due to inbreeding depression. Our results indicate that diversity has been maintained despite the continuous harvesting of raw leaf material in the area over recent decades. Finally, the results provide information essential for the design of a germplasm bank to protect the endangered medicinal plant species.