Towards resolving the Knautia arvensis agg. (Dipsacaceae) puzzle: primary and secondary contact zones and ploidy segregation at landscape and microgeographic scales
Abstract
In the present study, it has been demonstrated that Knautia arvensis is an intriguing taxon that shows variation in both genome copy number and monoploid genome size. Diploid and tetraploid cytotypes exhibit spatial segregation at all the geographical scales examined, including the Central European portion of the distribution range, the zone of ploidy overlap, the mixed-ploidy populations, and the selected mixed-ploidy plots within such populations.
Distributional and phenotypic data support the existence of both primary and sec- ondary zones of cytotype contact. Irrespective of taxonomic af?nity, ploidy level seems to be the major determinant of the strength of interploidy reproductive isolation.
In addition, our study also highlights the importance of involving different ontogenetic stages when assessing evolutionary processes in mixed-ploidy populations.