The rise of the Andes promoted rapid diversification in Neotropical Phlegmariurus (Lycopodiaceae)

Abstract

Tropical mountains are disproportionately biodiverse relative to their surface area, but the processes underlying their exceptional diversity require further study. Here, we use comparative phylogenetic methods to examine the impact of the Andean orogeny on the diversification of Neotropical Phlegmariurus, a species-rich lycophyte clade.We generated a time-calibrated phylogeny of 105 species of Neotropical Phlegmariurus and estimated lineage diversification rates. We tested for correlations between lineage diversification rates and species range size, niche breadth, elevational range amplitude, and mean elevation of occurrence. A recently developed macroevolutionary model was used to incorporate geological data and test for an association between diversification rates and the Andean uplift.Diversification rates of Neotropical Phlegmariurus are negatively correlated with species range size and positively correlated with mean elevation of species occurrence. The rise of the Andes is strongly associated with increased rates of diversification in Neotropical Phlegmariurus during the last 10 Myr.Our study demonstrates the importance of mountain-building events and geographical isolation of alpine populations as drivers of rapid diversification, even in spore-dispersed plants. This work also highlights the usefulness of combined phylogenetic, geological and ecological datasets, and the promise of comparative environment-dependent diversification models in better understanding the evolutionary origins of biodiversity.

Why mountains matter for biodiversity

“…In the same plant family, the complex interactions among surface uplift, pollinator shifts, geography and morphology were linked to explain the massive pulse of diversification among Andean taxa (Hughes, ; Lagomarsino, Condamine, Antonelli, Mulch, & Davis, ). Likewise, in Neotropical Phlegmariurius (Lycopodiaceae) uplift and range expansion were positively correlated with diversification rates (Testo, Sessa, & Barrington, ). In the diverse plant family Ericaceae, multiple mountain radiations have been documented that closely follow the formation of novel mountain habitats (Schwery et al, ).…”

Rapid plant diversification in the Andes does not require flowers

“…Testo et al . also demonstrate the importance of geographic isolation in structuring the diversification history of Phlegmariurus . By exploring correlations between diversification rates and various parameters related to species ecology and distribution, they show that diversification rates are highest for species with small range sizes, as well as for those at high elevation.…”

“…This increased statistical rigor has resulted in a nuanced understanding of plant diversification patterns within and between the different habitat types that constitute the tropical Andes (Pennington et al ., ; Hughes, ). In this issue of New Phytologist , Testo et al . (pp. 604–613) contribute to this rich body of literature via an in‐depth examination of diversification patterns in a clubmoss genus.

‘ Phlegmariurus displays the same macroevolutionary hallmarks of Andean diversification as myriad angiosperms clades – including recent, rapid diversification.’

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“…A new study by Testo et al . is among the first to explicitly examine the role of Andean uplift on diversification in a free‐sporing vascular plant lineage, the primarily Neotropical clubmoss genus Phlegmariurus (Lycopodiaceae; Fig. ).…”

Niches and radiations: a case study on the Andean sapphire‐vented puffleg Eriocnemis luciani and coppery‐naped puffleg E. sapphiropygia (Aves, Trochilidae)

“…Hence, forces in addition to variations in environmental parameters, such as natural selection or genetic drift, are prompting the radiation of these hummingbirds. Previous studies demonstrated the utility of niche modelling techniques to assess conservation, ecological, taxonomic biogeographic and evolutionary questions in the tropical Andes, including plants (Sanín et al 2016, Zutta and Rundel 2017, Nürk et al 2018, Oleas et al 2019, Testo et al 2019), insects (Moo-Llanes et al 2017, Scattolini et al 2018), amphibians (Ramos Pallares et al 2018, reptiles (Aguilar et al 2016), mammals (Ramoni-Perazzi et al 2012, Gutiérrez et al 2015, Gerstner et al 2018, Bennett et al 2019) and birds (Cadena and Cuervo 2010, Freile et al 2010, Jiguet et al 2010, Thomassen et al 2010, Velásquez-Tibatá et al 2013, Ramirez-Villegas et al 2014, Avendaño and Donegan 2015, Ramoni-Perazzi et al 2017. Thus, the results presented here are based on a solid background with regards to the applicability of niche modelling procedures in Neotropical environmental complex regions.…”