Recent origin of Neotropical orchids in the world’s richest plant biodiversity hotspot

Abstract

[190 words] 33not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/106302 doi: bioRxiv preprint first posted online Feb. 6, 2017; 2• The Andean mountains of South America are the most species-rich 34 biodiversity hotspot worldwide with about 15% of the world's plant species, in 35 only 1% of the world's land surface. Orchids are a key element of the Andean 36 flora, and one of the most prominent components of the Neotropical epiphyte 37diversity, yet very little is known about their origin and diversification. 38• We address this knowledge gap by inferring the biogeographical history and 39 evolutionary dynamics of the two largest Neotropical orchid groups 40 (Cymbidieae and Pleurothallidinae), using two unparalleled, densely-sampled 41 orchid phylogenies (including 400+ newly generated DNA sequences), 42 comparative phylogenetic methods, geological and biological datasets.

Plastid phylogenomics resolves ambiguous relationships within the orchid family and provides a solid timeframe for biogeography and macroevolution

“…Nonetheless, our ML tree also identifies intricate relationships that have been consistently recovered as unsupported in several studies. These include unsupported basal nodes in Epidendroideae representing Sobralieae, Nervilieae and Tiphoreae 27,48 , Arundina +remainder of Arethuseae 27 , and the position of Eulophiinae in the Cymbidieae 25,28,49 (Fig. 2).…”

“…Previous orchid studies have failed to resolve relationships in rapidly diversifying clades 24–26 because of reduced taxon and data sampling 27 . This is particularly true for Cymbidieae and Pleurothallidinae, the two most species-rich groups in which generic relationships are largely the product of rapid diversification 28 that is difficult to resolve using only a few loci 25,29 . Cymbidieae comprise 10 subtribes, ∼145 genera and nearly 3,800 species 1 , 90% of which occur in the Neotropics 28 .…”

“…This is particularly true for Cymbidieae and Pleurothallidinae, the two most species-rich groups in which generic relationships are largely the product of rapid diversification 28 that is difficult to resolve using only a few loci 25,29 . Cymbidieae comprise 10 subtribes, ∼145 genera and nearly 3,800 species 1 , 90% of which occur in the Neotropics 28 . Four of these subtribes are among the most species-rich in the Andean and Chocoan region (Maxillariinae, Oncidiinae, Stanhopeinae and Zygopetaliinae 30,31 ).…”

Hundreds of nuclear and plastid loci yield insights into orchid relationships

“…Other unusual characters of interest include the velamen, a tissue fostering water uptake and protecting orchid roots in epiphytic orchids (Zotz and Winkler, 2013; Chomicki et al, 2015) and their mostly anemochorous (Arditti and Ghani, 2000; Barthlott et al, 2014) or sometimes animal-dispersed seeds (ants, bats, bees, crickets and frugivorous birds; (Suetsugu et al, 2015; Morales-Linares et al, 2018). Their global distribution, high species-richness in the tropics and wide variety of functional traits and ecological interactions makes them an excellent model group for studying how biotic and abiotic factors affect their diversification (Givnish et al, 2015, 2016; Pérez-Escobar, Chomicki, Condamine, de Vos, et al, 2017; Pérez-Escobar, Chomicki, Condamine, Karremans, et al, 2017).…”

Andean uplift, drainage basin formation, and the evolution of riverweeds(Marathrum,Podostemaceae)in northern South America

“…However, by shifting the physical locations of watershed boundaries, connecting and disconnecting adjacent river basins, (Albert & Crampton, 2010; Hoorn et al , 2010; Tagliacollo et al , 2015; Ruokolainen et al , 2019) the uplift of the Andean Cordillera has also impacted the evolution of organisms living in rivers as has been shown in fish (Albert et al , 2006, 2020; Picq et al , 2014; Tagliacollo et al , 2015). The role of Andean uplift in Neotropical plant evolution has been investigated in terrestrial groups living in mountains (Richardson et al , 2018), where a correlation of Andean orogeny with increased diversification rates (Lagomarsino et al , 2016; Pérez-Escobar et al , 2017; Testo et al , 2019), and explosive radiation in taxa in high-elevation tropical ecosystems (Hughes & Eastwood, 2006; Madriñán et al , 2013; Nürk et al , 2013; Nevado et al , 2018) have been inferred. However, the impact of Andean uplift and landscape change in the region on plants in rivers remains unaddressed.…”