Equilibrium and non-equilibrium dynamics simultaneously operate in the Galápagos islands
Luis M. Valente 1,*, Albert B. Phillimore 2 and Rampal S. Etienne 3
Article first published online: 23 JUN 2015
DOI: 10.1111/ele.12461
© 2015 The Authors Ecology Letters published by John Wiley & Sons Ltd and CNRS.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords:
Community assembly; diversification; dynamic equilibrium; island biogeography; phylogeny
Abstract
Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galápagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galápagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms.
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