Table 3.
Karyological information in known Sorbus hybrids
| Taxon | 2n* | Ploidy | Ploidy based on FCM | Ratio observed (mean ± s.d.) | Ratio expected | Difference (obs. – exp.) |
|---|---|---|---|---|---|---|
| S. × thuringiaca (S. aucuparia× S. aria) | 34 | 2x | 2x | 1·505 | 1·506 | –0·001 |
| S. × tomentella (S. aria × S. torminalis) | 34 | 2x | 2x | 1·552 ± 0·007 | 1·551 | –0·001 |
| S. × avonensis (S. aria × S. porrigentiformis) | – | 3x† | 3x | 2·252 ± 0·058 | 2·250 | 0·004 |
| S. × liljeforsii (S. aucuparia × S. intermedia) | 51 | 3x | 3x | 2·349 | 2·270 | 0·079 |
| S. × robertsonii (S. aria × S. eminens) | – | 3x† | 3x | 2·271 | 2·260 | 0·011 |
| S. × houstoniae (S. aria × S. bristolensis) | – | 4x† | 4x | 3·072 | 3·063 | 0·009 |
| S. × motleyi (S. aucuparia × S. leyana) | – | – | 4x | 3·039 ± 0·013 | 3·026 | 0·013 |
* Chromosome numbers extracted from Rich et al. (2010).
† Ploidy levels inferred from molecular data (Houston et al., 2009; Robertson et al., 2010).
Note: the ratios expected were calculated on the basis of the parental genomes. The calculations in diploid and triploid hybrids were made by summing the relative ratio of reduced genomes in both parents. In the tetraploids, the calculations resulted from the sum of an unreduced triploid and reduced diploid parents.