Publication details
Constraints on interspecific hybridization intensity of Cirsium oleraceum-rivulare-palustre-acaulon complex (Asteraceae)
| Authors | |
|---|---|
| Year of publication | 2022 |
| Type | Conference abstract |
| Citation | |
| Description | The study was conducted to determine possible causes that allow or limit the interspecific hybridization intensity of Cirsium oleraceum-rivularepalustre-acaulon complex based on data of different field sites in Central Europe and herbarium records. Among the six possible hybridizing pairs of four Cirsium species studied, frequency of natural hybrids expressed by 641 herbarium specimens are 31.20 % of C. oleraceum x C. rivulare, 25.43 % of C. oleraceum x C. palustre, 22 % of C. oleraceum x C. acaulon and 21.22 % of C. palustre x C. rivulare. Cirsium acaulon rarely produce hybrids with C. rivulare (0.15 %) and C. palustre (0 %). The hybridization potential between species-pairs is estimated based on geographic, ecological similarities and floral phenological overlap constituting the premating reproductive barrier. Compared to the species pair acaulonrivulare, the species pairs oleraceum-acaulon and oleraceum-rivulare are 40-times higher in their geographical distributions and 12-times higher than oleraceum-palustre. However, no hybrid C. acaulon x C. palustre was detected. The ecological similarity between the potentially hybridizing species pairs are oleraceum-rivulare > palustre-rivulare > oleraceum-palustre > oleraceum-acaulon > acaulon-rivulare > acaulonpalustre. The floral phenological overlap between species pairs is as follows, oleraceum-acaulon > oleraceum-palustre > acaulon-palustre > palustre-rivulare > acaulon-rivulare > oleraceum-rivulare. Despite limitations, frequent natural hybridization suggests interspecific pollen competition plays a key role in determining the intensity of hybridization in each hybridizing pair. Future analyses of pollen-pistil interactions, in vivo pollen tube growth rates, will provide the best possible explanation for a wide variation in Cirsium hybrid intensity. |