Ecological segregation drives fine scale cytotype distribution of Senecio carniolicus (Asteraceae) in the Eastern Alps
Abstract
How cytotype mixture in populations is being maintained is a central question in evolutionary polyploidy research. In order to uncover patterns and processes of segregation of co-existing cytotypes, we investigated a contact zone of diploid and hexaploid individuals of the alpine herb Senecio carniolicus Willd. (Asteraceae) in the eastern Alps (Austria).
Linking the fine-scale distribution of cytotypes to environmental and spatial factors, segregation along an ecological gradient was found, which was also reflected by cytotype-associated plant assemblages. Compared to diploids, hexaploids are found in more species-rich and denser communities, which may be due to higher competitive capabilities and lower tolerance against abiotic stress of the polyploids.
The lack of any intermediate cytotypes suggests the presence of strong reproductive isolation mechanisms, whose nature is, however, elusive.