Andean Mountain Building Did not Preclude Dispersal of Lowland Epiphytic Orchids in the Neotropics

Oscar Alejandro Pérez-Escobar,Guillaume Chomicki,Bente B Klitgård,Emerson Pansarin,Günter Gerlach,Marc Gottschling,Fabien L Condamine

doi:10.1038/s41598-017-04261-z

Abstract

The Andean uplift is one of the major orographic events in the New World and has impacted considerably the diversification of numerous Neotropical lineages. Despite its importance for biogeography, the specific role of mountain ranges as a dispersal barrier between South and Central American lowland plant lineages is still poorly understood. The swan orchids (Cycnoches) comprise ca 34 epiphytic species distributed in lowland and pre-montane forests of Central and South America. Here, we study the historical biogeography of Cycnoches to better understand the impact of the Andean uplift on the diversification of Neotropical lowland plant lineages. Using novel molecular sequences (five nuclear and plastid regions) and twelve biogeographic models, we infer that the most recent common ancestor of Cycnoches originated in Amazonia ca 5 Mya. The first colonization of Central America occurred from a direct migration event from Amazonia, and multiple bidirectional trans-Andean migrations between Amazonia and Central America took place subsequently. Notably, these rare biological exchanges occurred well after major mountain building periods. The Andes have limited plant migration, yet it has seldom allowed episodic gene exchange of lowland epiphyte lineages such as orchids with great potential for effortless dispersal because of the very light, anemochorous seeds.

Highlights

Neotropical landscape and biodiversity have long drawn the attention of naturalists[1, 2]
The question remains whether Andean uplift has been an abiotic barrier to migration for epiphytic lineages such as lowland orchids and bromeliads, both being important components of Neotropical forests
Three migrations from Amazonia to Central America and back, respectively, took place ~2 million years ago (Mya), when the Northern and Central Andes already peaked at a mean elevation of 4000 m

Summary

Introduction

Neotropical landscape and biodiversity have long drawn the attention of naturalists[1, 2]. One of the most biologically important abiotic processes in the diverse geological history of the Americas is the rise of the Andes[7, 14, 20]. The fossil record (e.g. palynological[3, 21] and geological data: isotope measurements[22], sediment loads, apatite fission-track data7) collectively indicate that the Andean uplift was a partially constant process punctuated by periods of intensified mountain building. Two of the most intense uplift periods occurred around 12 (mid-Miocene) and 4.5 million years ago (Mya; early Pliocene[7]). The question remains whether Andean uplift has been an abiotic barrier to migration for epiphytic lineages such as lowland orchids and bromeliads, both being important components of Neotropical forests

Methods

Results

Discussion

Conclusion