Numerical taxonomic studies on Solanum L. section Solanum (Maurella)

Population differentiation was studied in 32 accessions belonging to Solanum L. section Solanum (Maurella); these accessions represented 20 species of four differing ploidy levels. A study of discordance demonstrated that the species exhibit considerable inherent discordant variation; it also provided an estimate of the relative variabilities of characters within these populations, and the consistency with which they differentiate populations. Hierarchic clusters, obtained using the single-link cluster method, confirmed the relative importance of the different classes of characters used for differentiation within this section. Similarly, the hierarchic clusters generally supported earlier taxonomic decisions. The use of a non-hierarchic cluster method provided the most interesting data on differentiation within the section Solanum, particularly for genome relationships of the polyploid taxa. This clustering pattern fitted well with known genome relationships, while also suggesting putative ancestors for other allopolyploids; suggestions deriving retrospective support from the hierarchic dendrograms. The progenitors suggested by tliese two clustering methods supported data derived from orthodox taxonomy, comparative morphology, hybridisation studies, the artificial synthesis of polyploids and seed protein band patterns.