Epidendrum (Orchidaceae) as a model system for ecological and evolutionary studies in the Neotropics

The orchid genus Epidendrum, with 1500 species occurring within the Neotropical region, represents a very promising model system for evolutionary and ecological studies offering an expanded repertoire of research opportunities in the breadth of modern plant biology. Epidendrum displays a significant degree of morphological variation, chromosome number diversity and ecological interactions, which challenges widely held views on reproductive barriers and habitat selection. The widespread geographical distribution of many species and populations offers interesting opportunities to investigate how climatic changes and historic demographic processes shaped the current patterns of genetic and species diversity across different biomes and landscapes. Questions involving chromosome barriers to gene exchange and the role of postzygotic genetic barriers in species cohesion (e.g., the contributions of habitat selection and niche divergence on species cohesion) could be easily addressed when using the variety of natural hybrid zones found across Epidendrum. Several key evolutionary questions could be addressed with this model system, such as the identification of the first stages of adaptive radiation, the evolution of pollination strategies, the adaptive ecological significance of trait variation and hybridisation, the influence of historical demographic events on lineage diversification and speciation. With the advance of cost-effective molecular techniques and by combining ecological and phenotypic data, researchers can now tackle these questions and foster significant progress in the field of Neotropical plant diversification and evolution. (AU)