Niche divergence promotes rapid diversification of East African sky island white-eyes (Aves: Zosteropidae).
Bottom Line: To explain their elevated diversity within this region, models founded on niche conservatism have been offered, although detailed phylogeographic studies are limited to a few avian lineages.Our results also highlight an underestimation of diversity compared to morphological studies that has implications for their taxonomy and conservation.Molecular dating suggests that the spatially extensive African radiation arose exceptionally rapidly (1-2.5 Ma) during the fluctuating Plio-Pleistocene climate, which may have provided the primary driver for lineage diversification.
Affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK; Bird Group, Department of Life Sciences, The Natural History Museum, Akeman Street, Tring, Hertfordshire, HP23 6AP, UK.Show MeSH
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Mentions: The application of different dating methods to the mitochondrial data (volcanic island calibration versus a 2.1% clock rate) results in divergent time frames for the radiation of African Zosterops. Implementation of the island calibration (Fig.3) estimates a Late Pleistocene divergence of 1.55 Ma (95% highest posterior density (HPD): 0.97–2.5 Ma). This is considerably younger than the time frame estimated by implementing the 2.1% clock (5.79 Ma 95% HPD: 4.8–6.86 Ma, Fig. S1, Supporting information) pushing the divergence of this clade back to the beginning of the Early Pliocene/Late Miocene. Previous estimates of the molecular rate of evolution in Zosteropidae have used island calibrations (Warren et al. 2006; Moyle et al. 2009; Melo et al. 2011) that have resulted in significantly faster rates of evolution than the 2.1% rate, suggesting that the avian clock may be a severe underestimation of the true rate of evolution within the Zosteropidae. Under the avian clock timescale, the divergence of the clade containing Grande Comore taxa Z. maderaspatanus kirki and Z. maderaspatanus maderaspatanus is dated at 1.68 Ma (95% HPD: 0.61–2.85 Ma), with a lower confidence interval marginally outside of the island age calibration of 0.5 Ma for the volcanic origin of Grande Comore.
Affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK; Bird Group, Department of Life Sciences, The Natural History Museum, Akeman Street, Tring, Hertfordshire, HP23 6AP, UK.