Recent origin and rapid speciation of Neotropical orchids in the world's richest plant biodiversity hotspot

Abstract

Summary The Andean mountains of South America are the most species‐rich biodiversity hotspot worldwide with c. 15% of the world's plant species, in only 1% of the world's land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification.We address this knowledge gap by inferring the biogeographical history and diversification dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely sampled orchid phylogenies (including more than 400 newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets.We find that the majority of Andean orchid lineages only originated in the last 20–15 million yr. Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and recolonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales.Our study sheds new light on the timing and geography of a major Neotropical diversification, and suggests that mountain uplift promotes species diversification across all elevational zones.

The contribution of temperature and continental fragmentation to amphibian diversification

“…Factors affecting the diversification of lineages are often placed in two categories: (a) the abiotic factors (Barnosky, 2001) and (b) the biotic factors (Van Valen, 1973). Thanks to recent methodological developments, the relative contribution of abiotic and biotic factors to the variation of speciation and extinction rates has been assessed in various groups using fossil data (Ezard, Aze, Pearson, & Purvis, 2011;Lehtonen et al, 2017;Liow, Reitan, & Harnik, 2015;Roalson & Roberts, 2016;Silvestro, Antonelli, Salamin, & Quental, 2015) or phylogenetic data (Condamine, Rolland, Höhna, Sperling, & Sanmartín, 2018;Condamine, Sperling, Wahlberg, Rasplus, & Kergoat, 2012;Lagomarsino, Condamine, Antonelli, Mulch, & Davis, 2016;Pérez-Escobar et al, 2017).…”

Digest: Drivers of coral diversification in a major marine biodiversity hotspot*

“…For example, in Andean orchids (Pérez‐Escobar et al. ), asynchronous migrations from adjacent regions followed by rapid diversification have led to extremely high species diversity in montane areas. This contradicts the museum hypothesis, whereby species accumulate at a constant rate over time with little extinction.…”

“…Diversification patterns of corals in the CT resemble the diversification dynamics of other eukaryotic lineages that are highly diverse in biodiversity hotspots. For example, in Andean orchids (Pérez-Escobar et al 2017b), asynchronous migrations from adjacent regions followed by rapid diversification have led to extremely high species diversity in montane areas. This contradicts the museum hypothesis, whereby species accumulate at a constant rate over time with little extinction.…”

Digest: Shape-shifting in Solanaceae flowers: The influence of pollinators*

“…; Gentry ; Pérez‐Escobar et al. ). It has been argued that the great variation in angiosperm flowers is largely influenced by pollinator‐mediated selection (Sauquet et al.…”

“…), a force that has also been linked with diversification of large groups within the flowering plants, such as orchids (Pérez‐Escobar et al. ). Micro‐evolutionary studies aimed at understanding mechanisms underpinning changes in observed phenotypes have clearly demonstrated that pollinator shifts are strongly correlated with changes in floral traits (e.g., Aquilegia ; Whittall and Hodges ).…”