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The interplay of past diversification and evolutionary isolation with present imperilment across the amphibian tree of life

Nature Ecology & Evolution volume 2, pages 850–858 (2018)Cite this article

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Abstract

Human activities continue to erode the tree of life, requiring us to prioritize research and conservation. Amphibians represent key victims and bellwethers of global change, and the need for action to conserve them is drastically outpacing knowledge. We provide a phylogeny incorporating nearly all extant amphibians (7,238 species). Current amphibian diversity is composed of both older, depauperate lineages and extensive, more recent tropical radiations found in select clades. Frog and salamander diversification increased strongly after the Cretaceous–Palaeogene boundary, preceded by a potential mass-extinction event in salamanders. Diversification rates of subterranean caecilians varied little over time. Biogeographically, the Afro- and Neotropics harbour a particularly high proportion of Gondwanan relicts, comprising species with high evolutionary distinctiveness (ED). These high-ED species represent a large portion of the branches in the present tree: around 28% of all phylogenetic diversity comes from species in the top 10% of ED. The association between ED and imperilment is weak, but many species with high ED are now imperilled or lack formal threat status, suggesting opportunities for integrating evolutionary position and phylogenetic heritage in addressing the current extinction crisis. By providing a phylogenetic estimate for extant amphibians and identifying their threats and ED, we offer a preliminary basis for a quantitatively informed global approach to conserving the amphibian tree of life.

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Fig. 1: Lineage-through-time plots of 100 time trees sampled from the Bayesian posterior distribution.
Fig. 2: Variation in net diversification rates of the three amphibian clades.
Fig. 3: Phylogeny of all extant amphibian species and their variation in ED.
Fig. 4: Biogeographic variation in amphibian phylogenetic structure as characterized by the probability density of ED values.
Fig. 5: ED of the top 100 most evolutionarily distinct amphibian species (median ED: >54 Myr) and their 2016 IUCN Red List threat status and clade affinity.
Fig. 6: Variation in ED by threat status categorization and main threat.

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Acknowledgements

We thank N. Upham, I. Quintero, R. Freckleton, D. Wake, J. Tonini, the GWU systematics group, and the VertLife group for discussions and comments on the manuscript. We are grateful to M. Duong for help with the figure design. We acknowledge support from NSF DEB-1441737, DEB-1558568 and NSF DBI-1262600 to W.J. and DEB-1441719 and DBI-0905765 to R.A.P.

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  1. Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA

    Walter Jetz

  2. Division of Biology, Imperial College London, Ascot, UK

    Walter Jetz

  3. Department of Biological Sciences, The George Washington University, Washington DC, USA

    R. Alexander Pyron

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Supplementary Materials and Methods; Supplementary Results and Analyses; Supplementary References; Supplementary Figures S1–S12.

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Supplementary Table S1

Evolutionary distinctness and threat status data for species in analysis

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Jetz, W., Pyron, R.A. The interplay of past diversification and evolutionary isolation with present imperilment across the amphibian tree of life. Nat Ecol Evol 2, 850–858 (2018). https://doi.org/10.1038/s41559-018-0515-5

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