The genetic legacy of fragmentation and overexploitation in the threatened medicinal African pepper-bark tree, Warburgia salutaris

The pepper-bark tree (Warburgia salutaris) is one of the most highly valued medicinal plant species worldwide. Native to southern Africa, this species has been extensively harvested for the bark, which is widely used in traditional health practices. Illegal harvesting coupled with habitat degradation has contributed to fragmentation of populations and a severe decline in its distribution. Even though the species is included in the IUCN Red List as Endangered, genetic data that would help conservation efforts and future re-introductions are absent. We therefore developed new molecular markers to understand patterns of genetic diversity, structure, and gene flow of W. salutaris in one of its most important areas of occurrence (Mozambique). In this study, we have shown that, despite fragmentation and overexploitation, this species maintains a relatively high level of genetic diversity supporting the existence of random mating. Two genetic groups were found corresponding to the northern and southern locations. Our study suggests that, if local extinctions occurred in Mozambique, the pepper-bark tree persisted in sufficient numbers to retain a large proportion of genetic diversity. Management plans should concentrate on maintaining this high level of genetic variability through both in and ex-situ conservation actions.

Development of national animal genetic resource programs

Globally, animal genetic resources are contracting due to economic forces. As a result, during the 1990s there was a dramatic increase in national animal genetic resource activities. Many national programmes were initiated and the Food and Agriculture Organisation of the United Nations played a prominent role in coalescing national actions. Nationally, programmes have been initiated that comprise of in situ, ex situ and information-exchange efforts. A critical element to national conservation efforts is the development of cryopreserved collections of germplasm. Several countries have initiated substantial multispecies collections of cryopreserved germplasm. The selection of animals within breeds of interest is an important consideration in building cryopreserved collections. Animal selection should be based on a lack of genetic relationship, with sufficient numbers of animals to ensure the capture of rare alleles. Major issues facing repository development and genetic conservation are: (1) that all breeds are in need of genetic diversity management; (2) a better understanding of in situ breed population dynamics is needed; and (3) the concept that repository collections can be used by a broad range of clientele across time as well as during emergency situations.