Running out of time to smell the roseroots: Reviewing threats and trade in wild Rhodiola rosea L.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhodiola rosea L. has a circumpolar distribution and is used in ethnomedicines of Arctic peoples, as well as in national systems of traditional medicine. Since the late 20th century, global demand for R. rosea has increased steadily, in part due to clinical research supporting new uses in modern phytotherapy. Global supply has been largely obtained from wild populations, which face threats from poorly regulated and destructive exploitation of the rootstocks on an industrial scale. AIM OF THE STUDY: To evaluate (i) the conservation status, harvesting and trade levels of R. rosea, in order to determine whether international trade should be monitored, (ii) the current state of experimental and commercial farming and whether cultivation may play a role to take pressure off wild stocks, and (iii) evidence of substitution of other Rhodiola species for R. rosea as an indicator of overexploitation and rarity. MATERIALS AND METHODS: We reviewed published studies on R. rosea biology and ecology, as well as information on impacts of wild harvest, on management measures at the national and regional levels, and on the current level of cultivation from across the geographic range of this species. Production and trade data were assessed and analysed from published reports and trade databases, consultations with R. rosea farmers, processors of extracts, and trade experts, but also from government and news reports of illegal harvesting and smuggling. RESULTS AND CONCLUSIONS: Our assessment of historical and current data from multiple disciplines shows that future monitoring and protection of R. rosea populations is of time-sensitive importance to the fields of ethnobotany, ethnopharmacology, phytochemistry and phytomedicine. We found that the global demand for R. rosea ingredients and products has been increasing in the 21st century, while wild populations in the main commercial harvesting areas continue to decrease, with conservation issues and reduced supply in some cases. The level of illegal harvesting in protected areas and cross border smuggling is increasing annually coupled with increasing incidences of adulteration and substitution of R. rosea with other wild Rhodiola species, potentially negatively impacting the conservation status of their wild populations, but also an indicator of scarcity of the genuine article. The current data suggests that the historical primary reliance on sourcing from wild populations of R. rosea should transition towards increased sourcing of R. rosea from farms that are implementing conservation oriented sustainable agricultural methods, and that sustainable wild collection standards must be implemented for sourcing from wild populations.

Spatial and ecological population genetic structures within two island-endemic Aeonium species of different niche width.

The Crassulacean genus Aeonium is a well-known example for plant species radiation on oceanic archipelagos. However, while allopatric speciation among islands is documented for this genus, the role of intra-island speciation due to population divergence by topographical isolation or ecological heterogeneity has not yet been addressed. The aim of this study was to investigate intraspecific genetic structures and to identify spatial and ecological drivers of genetic population differentiation on the island scale. We analyzed inter simple sequence repeat variation within two island-endemic Aeonium species of La Palma: one widespread generalist that covers a large variety of different habitat types (Ae. davidbramwellii) and one narrow ecological specialist (Ae. nobile), in order to assess evolutionary potentials on this island. Gene pool differentiation and genetic diversity patterns were associated with major landscape structures in both species, with phylogeographic implications. However, overall levels of genetic differentiation were low. For the generalist species, outlier loci detection and loci-environment correlation approaches indicated moderate signatures of divergent selection pressures linked to temperature and precipitation variables, while the specialist species missed such patterns. Our data point to incipient differentiation among populations, emphasizing that ecological heterogeneity and topographical structuring within the small scales of an island can foster evolutionary processes. Very likely, such processes have contributed to the radiation of Aeonium on the Canary Islands. There is also support for different evolutionary mechanisms between generalist and specialist species.