Origin and systematic position of Jacobaea vulgaris (Asteraceae) octoploids: genetic and morphological evidence
Abstract
Five cytotypes have been reported for Jacobaea vulgaris (syn.: Senecio jacobaea); three of them with euploid (tetraploid, hexaploid, and octoploid; 2n = 40, 60, and 80) and one with aneuploid (2n = 32) chromosome numbers. Among them, only tetra- and octoploid cytotypes are regularly found, the other two are very rare.
In this study we re-evaluated the origin and systematic position of J. vulgaris octoploids. DNA ploidy levels, morphological, and genetic (AFLP, amplified fragment length polymorphism) data were generated for 38 populations of J. vulgaris from Central and Eastern Europe, and adjacent parts of North-Western Europe.
Genetic dataset was supplemented with 16 populations of five closely related species: J. alpina, J. aquatica, J. erratica, J. erucifolia, and J. subalpina. The octoploid cytotype of J. vulgaris, known thus far only from Pannonia and Ukrainian Podillya regions, has also been found on two Baltic islands, A-land and Gotland.
AFLP analyses showed clear genetic differences between tetra- and octoploid cytotypes and revealed that all octoploid plants are most likely of autopolyploid origin. The AFLP data also indicate that octoploids form two separate allopatric and monophyletic lineages, one represented by Pannonian and A-land populations, and the other represented by the populations from Podillya and Gotland.
The octoploids from Gotland correspond to the previously recognized subspecies J. vulgaris subsp. gotlandica. The octoploids distributed in Pannonia are described here as a new subspecies, J. vulgaris subsp. pannonica.