Diversification of the orchid genus Tridactyle: origin of endemism on the oceanic islands of São Tomé & Príncipe in the Gulf of Guinea

Aim: Oceanic islands have played an important role in our understanding of the diversification of organisms, and phylogenetic estimates have been used in this context to investigate the origin of island diversity and its relationship to the continent. Using a typical orchid genus rich in island endemics and with widespread continental relatives, we aim to compare alternative hypotheses of diversification with a focus on island endemism.

Location: Tropical Africa and the Gulf of Guinea Islands of São Tomé & Príncipe, Central Africa.

Taxon: Tridactyle genus (Orchidaceae).

Methods: We used genome skimming to sequence the whole chloroplast genome and nuclear ribosomal genes from 157 individuals of 34 Tridactyle species and 15 individuals of 12 other orchid genera (outgroups) to infer a time-calibrated phylogenetic tree of the genus Tridactyle. We also used multiple statistical methods to infer the geographic ranges of the ancestral nodes from the estimated phylogeny. Alternativ...