The extremely large orchid diversity of the world’s species richest biological diversity hotspot, the Andes, formed only in the past 20 million years, says a new study led by researchers at Kew Gardens in London, University of Munich, University of Costa Rica and University of Gothenburg.
The team of scientists found that about 7000 orchid species from the American tropics – representing over a fifth of all species alive – formed only during the last 20 to 15 million years, from migrant species inhabiting the Amazonian rainforest and Central American mountains. The team also discovered that the rise of the Andes mountains, the world’s most species rich biological hotspot, strongly influenced the evolution of orchids by generating new habitats that the orchids further colonized. – “Orchids are not only popular in horticulture but also great models to understand evolution. Since orchids first appeared long before the extinction of dinosaurs, we were surprised to find out that so many species formed so recently”, says Professor Alexandre Antonelli at the Gothenburg Global Biodiversity Centre, senior author of the study.
The current distribution of orchids all over the American tropics posits the question of whether the formation of the Andean mountains blocked orchid migrations across the continent. The study shows that multiple recent migrations between Amazonia and Central America took place after most of the Andes were fully formed, contrasting with many animal groups and animal-dispersed plants for which the Andes constitute an important isolating barrier. – “The role of the Andean mountains as a geographical barrier for the migration of plant species in America has remained largely understudied. As for the particular case of orchids, it makes a lot of sense the fact that the rise of the Andes did not preclude ancient migrations from and to Amazonia because of the extremely tiny, light-weight seeds that can spend prolonged periods of time in the air”, says Dr. Guillaume Chomicki, one of the team members.
This research sets the stage for further research on the influence of how additional factors, such as plant-insect interactions, might also have contributed to the exuberantly high orchid diversity in South America. It also highlights the importance for conservation of the Andean mountain forests as the home of unique and extremely diverse orchid diversity.
Read the article:
Pérez-Escobar, O.A., G. Chomicki, F.L. Condamine, A.P. Karremans, D. Bogarín, N.J. Matzke, D. Silvestro & A. Antonelli
Recent origin and rapid speciation of Neotropical orchids in the world's richest plant biodiversity hotspot
NEW PHYTOLOGIST 215: 891–905. 2017