Metabolomic evidence for allopatric segregation in Espeletiinae (Asteraceae): a new perspective of an Andean adaptive radiation in sky islands

The biogeography of subtribe Espeletiinae, Asteraceae (Frailejones) and the effect of altitudinal barriers as evolutionary constrains in the Andes have been the focus of great debate. Several studies suggest that the Andean topography and past climatic history are important events for the development of current plant diversity in South America. Some clear evidence for geographic isolation of Andean-endemic groups has been recently obtained by genetic markers in an attempt to explain the explosive radiation of plant lineages in the páramos: a high altitude ecosystem that biogeographically functions as “sky islands” of open grassland vegetation isolated by deep valleys. The páramos topography along with the Pleistocene climatic fluctuations influenced the migration routes of Espeletiinae through the Andes and determined the evolution of the group, as demonstrated by their molecular phylogeny. However, molecular markers are too coarse to reveal subtle biogeographical trends in Espeletiinae and metabolomic evidence for allopatric segregation in plants has never been reported. In this work, we present for the first time a metabolomics approach based on UHPLC-HRMS and multivariate analyses to reveal subtle biogeographical trends in the diversification of the Frailejones. We used an untargeted metabolomics approach to study the metabolic profile of 210 samples of Espeletiinae belonging to five different genera. We demonstrate that different lineages of Espeletiinae can be distinguished by means of different metabolic profiles correlating to páramo massif of origin on a regional scale and to páramo complex on a local scale. In summary, our results suggest that Espeletiinae lineages modified their metabolic capacities as they evolved independently after the Pleistocene glaciations and that secondary metabolites may have played an important role in the diversification and adaptive success of the Frailejones to the Andean páramos, offering a new perspective of an Andean adaptive radiation in sky islands.