## 3 Results
### Genome Size  
The genome sizes (1C values) of the 33 _Crepis_ species and for _L. communuis_ were measured (Table 2). The genome sizes varied nearly seven-fold among the diploid species, ranging from 1.03 pg/1C DNA (_C. zacintha_) to 7.46 pg/1C DNA (_C. lacera_). The genome sizes of the species of the _Lagoseris_ evolutionary lineage were variable with nearly a six-fold difference (1.22 pg/1C DNA to 7.05 pg/1C DNA). In _Crepis_ s.s., larger genome sizes were found in two species from clade I (mean 1C value = 4.78 pg), whereas clade II species had smaller genome sizes (mean 1C value = 2.44 pg). In clade III, two diploid species _C. tectorum_ (3.06 pg/1C DNA) and _C. nicaensis_ (3.17 pg/1C DNA) had small genomes, whereas the octopololol _c. biennis_ had a larger genome (10.45 pg/1C DNA). The Cx-value (the C-value of monopolid genome \"x\") of _C. biennis_ was rather small (1C\({}_{x}\) = 2.61 pg/1C DNA; Figures 5 and S7) compared to the diploid species of this group. Three different groups of related species that differed in the patterns of their genome sizes distribution were identified in clade IV. The subclade IVa consisted of diploid species with larger genome sizes (mean 1C value = 6.35 pg) and, among them, _C. lacera_ had the largest estimated genome size (1C value = 7.46 pg). The genome sizes of the species from clade IVc were on average 2.52 pg/1C DNA. The largest variation in genome sizes was observed among the species in subclade IVb in which the genome size of _C. sibrica_ (1C value = 6.98 pg) was nearly seven times larger than that of _C. zacintha_ (1C value = 1.03 pg; Table 2; Figures 5 and S7). _C. vesciaria_ contained both diploid and tetraploid accessions (\(2n=8\) and \(2n=16\)). The genome sizes that were estimated for the diploid and tetraploid accessions (\(2.43\) pg/1C and \(2.78\) pg/1C, respectively).  
The DNA amounts were mapped onto the cpDNA ML phylogenetic tree using the maximum likelihood method (Figures 5 and S7). A genome size of 3.2 pg/1C DNA was inferred as the ancestral state for the _Lagoseris_ lineage. Both decreases and increases in genome sizes were inferred to have accompanied speciation and diversification of this clade (Figures 5 and S7). The ancestral genome size for the entire _Crepis_ s.s. lineage was reconstructed as 3.70 pg/1C. For clade I, 4.8 pg/1C was reconstructed as the ancestral state,whereas 2.50 pg/1C was recovered as the ancestral genome size for clade II. For the entire clade IV, 3.2 pg/1C was reconstructed as the ancestral genome size. For subclade IVa, the ancestral genome size was reconstructed to be 5.5 pg/1C, whereas for subclades IVb and IVc, 2.7 pg/1C and 2.9 pg/1C, respectively, were recovered. An increase in genome size was inferred for the species of clade I and the octopolid _C. biennis_ (clade III). In contrast, a reduction in genome size accompanied the evolution of many species of clade II and subclades IVb and IVc (e.g., _C. aureus_ and _C. zacintha_). The evolution of a common ancestor of subclade IVa was accompanied by an increase in the genome size, with further increases or decreases in the genome sizes inferred during the diversification and speciation of this clade.  
The inferences of genome size evolution were additionally performed using nrITS tree based on an extended data set containing both newly obtained genome size data and previously reported genome size estimations (Figure S8; Table S2). The extended data set included the species from the American agamic complex, which had relatively large genome sizes (Table S3). The observed values of the reconstructed ancestral states were slightly larger in comparison to the results of the analyses of the newly obtained data only. The inferred events of increases and reductions in genome size were very similar in both data sets.