# Chromosome Number and Genome Size Evolution in _Brasolia_ and _Sobralia_ (Sobralieaee, Orchidaceae)
## 3 Discussion  
### Phylogenetic Reconstruction  
Both methodologies, ML and BI, presented the same general topology and agreed with previously published literature [4; 5]. [PERSON] et al. [4] and [PERSON] et al. [5] noted that _Brasolia_ species (along with _Ellanthus_) and _Sobralia_ were placed on separate clades. It explicitly confirms the [PERSON] [6] attempt, followed by [PERSON] et al. [4], to place these two groups in two genera. The relationship between _Brasolia_ and _Ellanthus_ is hard to explain, especially considering the morphological distinctness between these two genera (compare Figure 1a-c with Figure 1d-j). The morphological differences between _Brasolia_ and _Ellanthus_ are much more visible than _Sobralia_ and _Brasolia_ morphological differences (compare Figure 1a-c with Figure 1d-j). Despite this, _Sobralia_ and _Brasolia_ formed two clades, both with high support. However, _Ellanthus_, even presenting apparent morphological differences from _Brasolia_, was placed nested on it in both phylogenies. Taking into account the present and previous phylogenetic studies, e.g., [4; 5; 6], one can suggest that _Brasolia_ should be transferred to _Ellanthus_. However, from the practical point of view, it is not supported as the taxa are morphologically distinct, and the _Ellanthus_ sampling is low. The _Ellanthus_ taxonomic circumscription remains an open question for future studies in which a broader Sobralieae sampling should be mandatory. Ancestral Base Chromosome Number Reconstruction Indicates Dysploidy as the Main Mechanism of Karyotype Evolution  
There were just three available data regarding Sobralieae chromosome number [8] and no data about genome size. However, such data is now enlarged to 23 chromosome numbers and 20 genome sizes. The chromosome number reported to _Sobralia_[8], 2\(n=48\), was recurrent among species analyzed here, present in 38.1% of the counts. Furthermore, we confirm 2\(n=50\) to _Ellanthus brasiliensis_[8]. Our data showed a sizeable dysploid variation in both _Brasolia_ and _Sobralia_, confirmed by the ancestral reconstruction analysis that suggested the descending dysploidy as the \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Index/Phylogenetic**} & \multicolumn{2}{c}{**Chromosome Number**} & \multicolumn{2}{c}{**Genome Size**} \\ \cline{2-5}  & **Maximum Likelihood** & **Bayesian Inference** & **Maximum Likelihood** & **Bayesian Inference** \\ \hline Pagel’s \(\lambda\) & 0.891 (\(p=0.0003\)) & 0.885 (\(p=0.0002\)) & 0.9875 (\(p=4.83\times 10^{-7}\)) & 0.9897 (\(p=3.53\times 10^{-7}\)) \\ Blomberg’s K & 0.276 (\(p=0.003\)) & 0.523 (\(p=0.001\)) & 1.00 (\(p=0.001\)) & 2.20 (\(p=0.001\)) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Pagel’s lambda and Blomberg’s K phylogenetic signals for chromosome number and genome size under Maximum Likelihood and Bayesian Inference. main mechanism of chromosome change in Sobralieae. Nevertheless, one should keep in mind that here dysploidy refers to chromosome number variation by one or few chromosomes and, in this sense, it includes both aneuploidy and dysploidy (for review see [9; 17]). The importance of dysploidy in orchol chromosome evolution was already suggested in different orchid groups as subtribe Pleurothalidiinae (tribe Cymbideae [18]) and the genera _Christensonella_ Szlach., Mytnik, Gorniak and Smiszek [19], _Heterotaxis_ Lindl. [16], _Bifrenaria_ Lindl. and close genera [20], all from subtribe Maximilarinae, tribe Cymbideae. In _Christensonella_ and _Heterotaxis_, it was possible to map the point involved in the fusion-fission rearrangement causing the dysploid variation, confirming the occurrence of fission-fusion (i.e., dysploidy variation) associated with DAPI\({}^{+}\) heterochromatic bands, reducing from \(2n=38\) to \(2n=36\) in the former genus [19] or with rDNA 45S, reducing from \(2n=42\) to \(2n=40\) in the last genus [15].