Biogeographical history and coalescent species delimitation of Pacific island skinks (Squamata: Scincidae: Emoia cyanura species group)

Journal of Biogeography
By: , and 




A prevailing hypothesis for how Pacific islands organisms have obtained their extant distributions is that of a stepping-stone model, in which populations originate from Papua New Guinea in the western Pacific and gradually disperse eastward. Here, we test this model using a spatiotemporal framework for Emoia cyanura and E. impar, two species within the Emoia cyanura species group (ECSG; Family: Scincidae). We further assess species limits within the group, utilizing novel coalescent methods.


Pacific Islands.


We obtained DNA sequence data from one mitochondrial and three nuclear markers for 117 individuals, representing seven of the nine species within the ECSG. These data were analysed for concordance with the stepping-stone model using estimation of population structure, divergence dates, and historical biogeographical range. To assess hypotheses of independent lineages within each widespread species, we also employed the Bayesian Phylogenetics & Phylogeography (BPP) program to define operational taxonomic units in *BEAST.


Population structure analyses consistently found individuals from western island groups representing divergent populations, with central and eastern populations demonstrating minimal genetic variation. Phylogenetic hypotheses support a western origin for E. cyanura and E. impar, while biogeographical and divergence time estimations predict a recent and rapid expansion out of the western Pacific. The BPP and *BEAST analyses found evidence for five independent lineages within E. impar and five independent lineages within E. cyanura/E. pseudocyanura.

Main conclusions

In contrast to the expectations of a stepping-stone model, E. cyanura and E. impar each exhibit the genetic signature of a rapid radiation during the mid to late Pleistocene, with evidence for newly identified lineages, mainly on western islands. Of these recovered lineages, we propose three to be elevated to species status. These findings expand our understanding of endemic Pacific biota, which are subject to conservation threats from human impacts and climate change.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Biogeographical history and coalescent species delimitation of Pacific island skinks (Squamata: Scincidae: Emoia cyanura species group)
Series title Journal of Biogeography
DOI 10.1111/jbi.12772
Volume 43
Issue 10
Year Published 2016
Language English
Publisher Blackwell Scientific Publications
Contributing office(s) Western Ecological Research Center
Description 13 p.
First page 1917
Last page 1929
Other Geospatial Pacific islands
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details