Origin and genetic differentiation of pink-flowered Sorbus hybrids in the Western Carpathians.
Diversity of the genus Sorbus has been affected by interspecific hybridizations. Pink-flowered hybrid species have been insufficiently studied so far. They comprise bigenomic hybrid species derived from crosses S. aria s.l. × S. chamaemespilus and trigenomic ones, where S. aucuparia was involved as well. The main objective of the present study was to reconstruct their hybrid origins as well as to assess genetic distinction among several morphologically recognized hybrid species.



Samples from putative maternal species and eight pink-flowered and two white-flowered hybrid species were collected in the Western Carpathians and the Sudetes. In total, 370 specimens were analysed. Six chloroplast microsatellites were used to infer parentage, whereas nuclear amplified fragment length polymorphism (AFLP) markers were employed for the identification of clones and patterns of genetic variation. Ploidy levels were estimated by flow cytometry on a subset of 140 individuals.



Genetic data supported their hybrid origins proposed based on flower and leaf morphology, and chloroplast DNA (cpDNA) revealed recurrent origins ( S. caeruleomontana , S. haljamovae ), even from bidirectional hybridization events ( S. zuzanae ). All bigenomic and trigenomic hybrid species (except triploid S. zuzanae ) were found to be tetraploid. In addition to polyploidy, low genetic variation and the presence of clones within and among populations were observed, suggesting predominantly apomictic reproduction of the hybrid species. Most of the described hybrid species appeared also genetically distinct.



The data suggest that multiple hybridization events in the Western Carpathian Sorbus have led to the formation of separate, partially reproductively isolated genetic lineages, which may or may not be discriminated morphologically. Even bidirectional hybridization can produce individuals classified to the same taxon based on phenotype. For some hybrid taxa, hybridization pathways were proposed based on their genetic proximity to parental species and differences in genome sizes.
Technical University in Zvolen, Faculty of Forestry, TG Masaryka 24, 96053 Zvolen, Slovakia.
Veronika
V
Uhrinová
Slovak Academy of Sciences, Institute of Botany, Plant Science and Biodiversity Centre, Dúbravská cesta 9, 84523 Bratislava, Slovakia.
Judita
J
Zozomová-Lihová
Comenius University, Botanical Garden, Detached Unit, 03815 Blatnica 315, Slovakia.
Dana
D
Bernátová
Senckenberg Research Institute and Natural History Museum, Department of Botany and Molecular Evolution, Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
Juraj
J
Paule
Technical University in Zvolen, Faculty of Forestry, TG Masaryka 24, 96053 Zvolen, Slovakia.
Ladislav
L
Paule
Technical University in Zvolen, Faculty of Forestry, TG Masaryka 24, 96053 Zvolen, Slovakia.
Dušan
D
Gömöry
D054458:Amplified Fragment Length Polymorphism Analysis; D005075:Biological Evolution; D018742:DNA, Chloroplast / Q000235:genetics; D014644:Genetic Variation; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D011123:Polyploidy; D018154:Slovakia; D031994:Sorbus / Q000235:genetics*
D018742:DNA, Chloroplast
Hybridization; Sorbus aria agg.; Sorbus aucuparia; Sorbus chamaemespilus; allopolyploidy; apomixis; trigenomic hybrid