Cytogeography of Pilosella officinarum (Compositae): Altitudinal and Longitudinal Differences in Ploidy Level Distribution in the Czech Republic and Slovakia and the General Pattern in Europe
Abstract
Pilosella officinarum (syn. Hieracium pilosella) is a highly structured species with respect to the ploidy level, with obvious cytogeographic trends.
Previous non-collated data indicated a possible differentiation in the frequency of particular ploidy levels in the Czech Republic and Slovakia. Therefore, detailed sampling and ploidy level analyses were assessed to reveal a boundary of common occurrence of tetraploids on one hand and higher ploids on the other.
For a better understanding of cytogeographic differentiation of P. officinarum in central Europe, a search was made for a general cytogeographic pattern in Europe based on published data. The recent distribution of P. officinarum in Europe is complex and probably reflects the climatic changes during the Pleistocene and consequent postglacial migrations.
Probably both penta- and hexaploids arose independently in central Europe (Alps and Carpathian Mountains) and in northern Europe (Scandinavia, Great Britain, Ireland), where the apomictic plants colonized deglaciated areas. We suggest that P. officinarum is in fact an amphidiploid species with a basic tetraploid level, which probably originated from hybridizations of diploid taxa from the section Pilosellina.