Similar diversification patterns in “sky islands”: A comparative approach in lineages from campo rupestre and campo de altitude

Campo rupestre and campo de altitude are two highly diverse plant formations that are found in montane areas in eastern Brazil. These formations are associated with landscapes having different geological histories and are part of different phytogeographic domains under different climatic conditions. It is unclear however, whether lineages in each area have different diversification dynamics and climatic niche evolution. Here we analyze biogeographical history, climatic niche evolution and diversification dynamics of the Cambessedesieae (Melastomataceae), a clade with many endemics in each formation. We use a time-calibrated phylogenetic tree alongside carefully curated distribution points to estimate ancestral ranges and compare diversification dynamics and climatic niche evolution across the group, using models of geographical range evolution (BioGeoBEARS), diversification dynamics (BAMM, GeoSSE) and trait-evolution (l1ou). Our results show that Cambessedesieae is a relatively old (Early Eocene, 48 Mya) clade in comparison to other lineages of similar distribution. An initial split between lineages that are mainly endemic to either formation happened earlier, but, surprisingly, these two lineages have similar diversification dynamics and climatic niche evolution. Shifts in climatic regimes in extant lineages occurred more recently and are not associated with changes in diversification rates. Overall, we show that lineages endemic to montane areas and having different geological histories and in different climatic and phytogeographic contexts can have similar diversification patterns.