# Chromosome Number and Genome Size Evolution in _Brasolia_ and _Sobralia_ (Sobralieaee, Orchidaceae)
## 2 Results
### Chromosome Number and Genome Size Varies in Sobralieae
Further descending dysploidies could be observed on _S. crocea_ and _S. fragrans_, reaching x = 22, and _B. cattleva_ and _B. dichotoma_, reaching x = 23 (ML and IB). Only one ascending dysploidy was detected in both trees, on the node of _Ellenanthus_ genus with x = 25 (Figure 2). Despite statistics test could not differentiate _Brasolia_ and _Sobralia_ based on genome size (F = 0.488; \(p\) = 0.487), the ancestral reconstruction for genome size suggested a higher ancestral 1C-value for _Sobralia_ (1C = 5.5 pg) compared to _Brasolia_ (1C = 4.45-4.73 pg) (Figure 2). Some punctual amplifications could be observed inside each genus, even without any important chromosome number variation. For example, the species _S. wilsonian_ (1C = 4.25 pg), _S. rosea_ (1C = 5.93 pg), _S. macrantha_ (1C = 6.24 pg), and _S. luerorum_ (1C = 8.05 pg) strongly vary among their 1C-values (Figure S1), although they present the \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**MODELS**} & \multicolumn{2}{c}{**Maximum Likelihood**} & \multicolumn{2}{c}{**Bayesian Inference**} \\ \cline{2-5}  & **Log-Likelihood** & **AIC** & **Log-Likelihood** & **AIC** \\ \hline Constant Rate & \(-\)51.76 & 109.5 * & \(-\)47.99 & 102 * \\ Constant Rate with & \(-\)51.76 & 109.5 * & \(-\)47.99 & 102 * \\ Constant Rate with & & & & \\ demi-polylploidy _est_ & \(-\)51.76 & 111.5 & \(-\)47.99 & 104 \\ Constant Rate without & & & & \\ polyploid (null model) & \(-\)51.76 & **107.5** & \(-\)47.99 & **99.99** \\ Linear rate & \(-\)50.92 & 111.8 & \(-\)47.71 & 105.4 \\ Linear rate with & & & & \\ demi-polylploid _est_ & \(-\)50.92 & 113.8 & \(-\)47.69 & 107.4 \\ Linear rate without & & & & \\ polyploid (null model) & \(-\)50.92 & 109.8 & \(-\)47.71 & 103.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: ChromEvol model results to infer the ancestral base chromosome number and the chromosome number changes in the tribe Sobraliinae. The analysis was carried out for Maximum Likelihood and Bayesian Inference phylogenetic trees. For each tested ChromEvol model for each phylogenetic method, the Log-likelihood and AIC values are presented. The lowest AIC in each phylogenetic tree is indicated in bold and * indicates alternative model that does not differ from the lowest AIC. same chromosome number 2n = 48 (\(n=24\); Figure 2). Inside _Brasolia_, genome size increase could be observed in _B. altissima_ (1C = 6.37 pg, 2n = 46; Figure 2). A genome size reduction could be observed in _S. crocea_ (1C = 3.77 pg, 2\(n=44\)) and _S. fragrans_ (1C = 3.43 pg, 2\(n=42\)) and in _B. portillae_ (1C = 3.3 pg, 2\(n=48\)). An additional important genome size reduction was also observed in _E. criinipes_ that presented half of the genome size (1C = 2.04 pg) compared with _E. brasiliensis_ (1C = 4.79 pg), but with the same chromosome number (2\(n=50\) for both species; Figure 2). Chromosome number presents no phylogenetic signal considering both phylogenetic trees, ML and BI, and tested indexes, [PERSON]'s lambda and Blomberg's K suggesting that phylogenetic history has a minimal effect on both traits (Table 3). Otherwise, genome size seems to present phylogenetic signal considering both phylogenetic trees, ML and BI, and tested indexes, [PERSON]'s lambda (values very close to 1) and Blomberg's K (values equal or superior to 1; see Table 3). Following the concept of phylogenetic signal, i.e., related species seems to present similar traits more than they resemble species drawn at random in this group, the phylogenetic signals for genome size suggested that this trait could reflect the evolutionary history of _Brasolia-Ellanthus-Sobralia_, being a potential informative trait to discuss the genera delimitation.