DISPERSAL STRATEGIES IN ROCCELLINA-CAPENSIS (ARTHONIALES)

Morphological, anatomical, chemical and ecological evidence show that the South African lichen Roccellina capensis (Nyl, ex Stizenb.) Tehler has developed a dispersal strategy with either sexually dispersed ind ividuals, or vegetatively dispersed, sorediate individuals, hence a pu tative species-pair. The concept 'species-pair' is well-known and wide ly used in lichenology. It refers to closely related, morphologically indistinguishable lichens that differ from each other by their dispers al strategies only. The so-called 'primary species' produces fruiting bodies and sexual spores, while its counterpart, the 'secondary specie s' is vegetatively dispersed by soredia, isidia or fragmentation. Our study uses molecular information to investigate if R. capensis should be treated as a species-pair or not. The internal transcribed spacer ( ITS) of the nuclear ribosomal DNA was sequenced for 17 specimens of R. capensis in order to rest if sexual and asexual (sorediate) specimens would group into two distinct, monophyletic groups. Such grouping wou ld support their recognition as separate taxa in a species-pair. We al so investigated whether the randomly amplified polymorphic DNA (RAPD) Method would be a suitable procedure in population studies of lichens. The analysis of the ITS region produced a single most parsimonious tr ee. The sexual and asexual specimens were grouped according to their g eographical distribution, rather than according to their dispersal str ategy. This result clearly shows thar the sexual and asexual specimens of R. capensis do not represent a species-pair. The RAPD data set pro duced an almost completely unresolved tree due to several homoplasious characters, possibly a result of algal contamination. (C) 1998 The Br itish Lichen Society.