CHLOROPLAST DNA AND ISOZYME ANALYSIS OF THE PROGENITOR-DERIVATIVE SPECIES RELATIONSHIP BETWEEN SENECIO-NEBRODENSIS AND S-VISCOSUS (ASTERACEAE)

A comparison of chloroplast DNA (cpDNA) and isozyme diversity in Senec io nebrodensis L., a species restricted to certain mountain ranges in Spain, and S. viscosus L., a widespread ruderal species in Europe, rev ealed that S. viscosus possessed the more common of two cpDNA haplotyp es resolved in S. nebrodensis and contained only a small subset of the alleles found in S. nebrodensis at enzyme coding loci. The two specie s shared one restriction length mutation and one site mutation in thei r cpDNA, which distinguished them from other European Senecio species examined previously. Taken overall, these results support the hypothes is that S. nebrodensis and S. viscosus are related as a progenitor-der ivative pair of species. The fact that no novel alleles were found in S. viscosus would suggest a relatively recent origin of the species, m ost probably in late glacial or postglacial times.