Impact of interspecific hybridization within a polyploid agamic complex of Pilosella (Asteraceae, Cichorieae) in Bulgaria compared with Central Europe

• Published in: Willdenowia Vol. 48; no. 3; pp. 345 - 362
• Main Authors: Krahulcová, Anna, Krahulec, František, Vladimirov, Vladimir
• Format: Journal Article
• Language: English
• Published: Botanic Garden and Botanical Museum Berlin-Dahlem (BGBM) 01-12-2018; Botanic Garden and Botanical Museum Berlin (BGBM), Freie Universität Berlin
• Subjects: Asteraceae; Bulgaria; Central Europe; Cichorieae; Compositae; facultative apomixis; Hieracium s.l; hybridization; microevolution; mixed-ploidy populations; Pilosella; residual sexuality; TAXONOMY OF PLANTS OF EUROPE AND THE MEDITERRANEAN; unreduced gametes
• ISSN: 0511-9618; 1868-6397
• DOI: 10.3372/wi.48.48302

The species-mixed Pilosella populations comprising diploid sexual and polyploid facultatively apomictic biotypes were studied in Bulgaria. Parentage of co-occurring recent hybrids was inferred from a combination of morphology and ploidy level that corresponded to simple/multiple crosses of basic species via either reduced or unreduced gametes. The flow cytometric seed screening illustrated the capacity for heteroploid hybridization both in open-pollinated plants in the mixed-ploidy populations and in crossing experiments. The diploid sexual species in Bulgaria have a limited impact on interspecific hybridization, and simple inter-cytotype hybrids are only sporadically formed. The origin of the most common hybrids in Bulgaria that are apomictic and retain the pentaploid/hexaploid ploidy level of a co-occurring putative apomictic parent remains unclear. The absence of stabilized hybridogeneous species and scarcity of commonly hybridizing polyploid sexual biotypes are crucial attributes that distinguish the Pilosella populations in Bulgaria from those in the Czech Republic and Germany. No recent high-polyploid hybrids of 2n + n origin that would potentially become drivers of ongoing hybridization in the mixed sexual-apomictic Pilosella populations similar to those in Central Europe have been recorded in Bulgaria. The pattern of co-occurring cytotypes in Bulgaria likely limits interspecific hybridization due to stronger ploidy barriers. Citation: Krahulcová A., Krahulec F. & Vladimirov V. 2018: Impact of interspecific hybridization within a polyploid agamic complex of Pilosella (Asteraceae, Cichorieae) in Bulgaria compared with Central Europe. – Willdenowia 48: 345–362. doi: https://doi.org/10.3372/wi.48.48302 Version of record first published online on 8 October 2018 ahead of inclusion in December 2018 issue.