Genetic variations in the endangered Sicilian endemic Brassica rupestris: proposals for a conservation strategy

Brassica rupestris Raf. is a chasmophyte species that includes two subspecies, both endemic to Central-Western Sicily (Italy). ISSR markers were used to detect genetic diversity within and among eight populations representative of the species’ distribution range. High levels of genetic diversity were revealed both at the population (PPB=53.88%, H S=0.212, Sh=0.309) and at the species level (PPB=96.55%, H T=0.307, Sh=0.464). The correlation between genetic and geographical distances was negative (Mantel test, r=−0.06 P<0.95). The two subspecies of B. rupestris, subsp. rupestris and subsp. hispida, showed remarkable genetic similarity and molecular data did not unequivocally support their distinctness. The pattern of genetic variation revealed by our study bears important consequences for conservation management: it is desirable to preserve B. rupestris populations in situ with a “dynamic” strategy, while, ex situ conservation programmes might be improved to safeguard maximum genetic diversity.