Hybridization may endanger the rare North Apennine endemic Cirsium bertolonii

Abstract We examined populations of North Apennine stenoendemics Cirsium bertolonii in the Apuan Alps and Tuscan-Emilian Apennines found individuals morphologically shifted to co-occurring C. acaulon or erisithales . Hybrid status these intermediates was confirmed by flow cytometry, morphometrics amplified fragment length polymorphism (AFLP). interpreted hybrids taxonomically as × sagrense ( ) abetonense ). Estimated genome size (2C) 2244 ± 31 Mbp for 2152 99 Their genomic GC content 38.95 0.35% 38.77 0.26%, respectively. Diploid chromosome number 2 n = 34 counted C , previously reported 12 needs be considered erroneous. a gynodioecious species (like many other species) that is not reproductively isolated ploidy level from congeners. The relatively frequent occurrence Monte Sagro locus classicus prevalence Alpe Tre Potenze suggest hybridization occurs repeatedly also older herbarium specimens. produces ripe achenes F2 backcrosses, some do. Genetic erosion/swamping via interspecific can therefore pose risk genetic integrity it does narrowly endemic high-mountain Europe.