## 3 Results
### Chromosome Number  
The chromosome numbers were analysed for 50 accessions (Table 2) representing 40 _Crepis_ species and three accessions of _L. communis_. Most of the analysed _Crepis_ species were diploids and only four polyploids were found, _C. biennis_ (\(2n=8x=40\)), _C. occidentalis_ (\(2n=4x=44\)), and _C. vesicularia_, which were represented by two polyploid accessions (both \(2n=4x=16\)) and one diploid accession (\(2n=2x=8\); Table 2; Figure S2). Five different chromosome base numbers were found among the diploid _Crepis_ species: \(x=3\), \(4\), \(5\), \(6\), and \(11\) (Table 2; Figures 2,3 and S4). The most common chromosome base numbers were \(x=4\) found in 20 species and \(x=5\) found in ten species. Six species had \(x=6\) and only two species had a chromosome base number of \(x=3\) (_C. capillaries_ and _C. zacintha_). The chromosome base number of \(x=11\) was found in _C. occidentalis_, a representative of the American _Crepis_ agamic complex (\(2n=4x=44\); Figure S5). _L. communis_ from the _Lagoseris_ clade was diploid with \(2n=14\). Figure 1: Phylogenetic relationships among the analysed _Crepis_ species based on the nrITS and the cpDNA data sets. Bootstrap support values are indicated at each node. Names of the species that were recovered in different positions in the two datasets are indicated in colour. The trees were rooted with _Picris hieracoides_, _Lactuca serriola_, and _Sonchus olercus_. The ML analysis (ChromEvol 2.0) was based on the cpDNA due to better support obtained for this marker. The ancestral chromosome base number for the common ancestor of _Lagoseris_ and _Crepis_ s.s. was inferred as \(x=6\) (pp = 0.97; Figure 4). The analysis of the cpDNA data sets suggested fourteen reductions (with expectation above 0.5) in the chromosome base numbers (Figure 4), three in the _Lagoseris_ group and eleven in _Crepis_ s.s. The ancestral base numbers for clades I and II was reconstructed as \(x=6\). The chromosome base number of \(x=5\) was inferred for the common ancestor of the species in clades III and IV (Figure 4). There was a further decrease in the chromosome base number from \(x=5\) to \(x=4\) in the evolutionary lineage of _C. tectorum_ and _C. nigrescens_ and in the evolutionary  
Figure 3: Karyograms representing each of the karyotype formula distinguished among the analysed _Crepis_ species: (**A**) _C. pammonia_; (**B**) _C. pediida_ subsp. _rhoacidifolia_; (**C**) _C. zacintha_; (**D**) _C. sriaca_; (**E**) _C. kotschyama_; (**F**) _C. sviscaria_ 2_; (**G**) _C. vesicular_ 1; (**H**) _C. leutodottooides_; (**I**) _C. oporinoides_; (**J**) _C. oapillaris_. Letters below each pair of chromosomes indicate the type of chromosome: m—metacentric; sm—submetacentric; and st—subtelocentric. The metaphase plates used to prepare the karyograms are presented in Figure S3. Scale bar = 5 \(\upmu\)m.  
Figure 2: Karyograms representing each of the karyotype formula distinguished among the analysed _Crepis_ species: (**A**) _Lapsana communis_; (**B**) _C. magellensis_; (**C**) _C. jacquinti_; (**D**) _C. paltosa_; (**E**) _C. succisifolia_; (**F**) _C. lyrate_; (**G**) _C. nicaensis_. Letters below each pair of chromosomes indicate the type of chromosome: m—metacentric; sm—submetacentric; and st—subtelocentric. The metaphase plates used to prepare the karyograms are presented in Figure S2. Scale bar = 5 \(\upmu\)m.  
lineage of _C. nicaeensis_ in clade III (Figure 4). A reduction in the chromosome base number from \(x=5\) to \(x=4\) accompanied the diversification of the common ancestor of the species in subclade IVa (Figure 4). Several events of descending dysploidy were also inferred for subclades IVb and IVc: (i) from \(x=5\) to \(x=4\) in the _C. kotschyana_ lineage and _C. setosa_ lineages; independently in the group that consisted of _C. taraxacifolia_, _C. vesicaria_, and _C. polymorpha_; in the lineages of _C. aculeata_ and _C. aspera_; as well as for the common ancestor of the group, consisting of _C. alpestris_, _C. oporinoides_, _C. pyrenaa_, and _C.