Conservation of the critically endangered Rumex rothschildianus as implied from AFLP diversity

Rumex rothschildianus (Polygonaceae) is a small dioecious annual endemic to the central coastal plain of Israel. This very rare sorrel is on the verge of global extinction, as its total gene pool consists of two surviving populations only: one small and the other relatively large and flourishing. The other ten populations of this species recorded during the 20th century (all in Israel) are now extinct. Amplified fragment length polymorphism (AFLP) markers were used to evaluate the population genetic structure of the two remaining populations. Genetic diversity in R. rothschildianus was H=0.17 with 48.9% polymorphic loci. Gene flow values suggest that the differentiation between the two populations is moderate (mean Fst=0.09). Considering these genetic data, two conservation management strategies should be applied: (1) Large scale reseeding in a neighbouring nature reserve to maintain the genetic diversity detected in this study. Seeds from diverse sources should be used for repeated reseedings in order to prevent the reintroduced populations from going through a genetic bottleneck or suffering genetic drift. (2) To maintain the genetic diversity in the two remaining wild populations, and to avoid risks such as possible outbreeding depression, only intrapopulation reinforcement should be considered. These populations should be carefully monitored and protected.