From tree tops to the ground: Reversals to terrestrial habit in Galeandra orchids (Epidendroideae: Catasetinae)

Publication date: Available online 30 June 2018Source: Molecular Phylogenetics and EvolutionAuthor(s): Aline C. Martins, Thuane Bochorny, Oscar A. Pérez-Escobar, Guillaume Chomicki, Silvana H.N. Monteiro, Eric de Camargo SmidtAbstractThe colonization of the epiphytic niche of Neotropical forest canopies played an important role in orchid’s extraordinary diversification, with rare reversions to the terrestrial habit. To understand the evolutionary context of those reversals, we investigated the diversification of Galeandra, a Neotropical orchid genus which includes epiphytic and terrestrial species. We hypothesized that reversion to the terrestrial habit accompanied the expansion of savannas. To test this hypothesis we generated a comprehensive time-calibrated phylogeny and employed comparative methods. We found that Galeandra originated towards the end of the Miocene in Amazonia. The terrestrial clade originated synchronously with the rise of dry vegetation biomes in the last 5 million years, suggesting that aridification dramatically impacted plant diversification and habits in the Neotropics. Shifts in habit impacted floral spur lengths and geographic range size, but not climatic niche. The longer spurs and narrower ranges characterize epiphytic species, which probably adapted to specialized long-tongued Euglossini bee pollinators inhabiting forested habits. The terrestrial species present variable floral spurs and wider distribution ranges, with evidence of self-pollina...

Source: Molecular Phylogenetics and Evolution - July 10, 2018 Category: Molecular Biology Source Type: research