Specias delimitation and assessment of genetic variability in Carpobrotus (Alzoaceae): evidence from amplified fragment length polymorphisms

Abstract

Species of Carpobrotus (Aizoaceae: Ruschioideae) are widely spread throughout South Africa and are commonly used for their medicinal properties. The genus consists of 13 species of which seven occur in South Africa, five in Australia and one in Chile. A number of investigations on South African species have demonstrated that some taxa exhibit anti-microbial activity. Using AFLPs (amplified fragment length polymorphisms) this study was undertaken with the primary aim of resolving relationships between Carpobrotus species in South Africa, and determining species limits by assessing their genetic distinctness. In addition, levels of genetic variability among populations of two South African species, C. acinaciformis and C. edulis werc assessed in more detail. AFLPs were not able to resolve conflict surrounding species boundaries, perhaps due to extensive hybridization. However, major groupings within South African species were identified, although no geographical structuring of these populations was evident. From a bio-prospecting perspective caution needs to be taken when sampling Carpobrotus due to difficulty in identifying species possibly as a result of hybridization.