Journal article
Islands Promote Diversification of the Silvereye Species Complex: A Phylogenomic Analysis of a Great Speciator
Molecular Ecology, Vol.34(14), pp.1-16
2025
PMCID: PMC12237087
PMID: 40497404
Abstract
Geographic isolation plays a pivotal role in speciation by restricting gene flow between populations through distance or physical barriers. However, the speciation process is complex, influenced by the interplay between dispersal ability and geographic isolation, as seen in "great speciators" - bird species that simultaneously have broad island distributions but high levels of subspecific diversity. Comparing genomic population differentiation in species that occupy both continental and island settings can reveal the effects of different forms of geographic isolation and validate if the primary mechanism proposed to catalyse a great speciator pattern, that is, dispersal reduction following island colonisation, has occurred. The highly diverse white-eye family Zosteropidae includes several great speciators, including the silvereye (Zosterops lateralis), with 16 subspecies (11 occurring on islands), distributed on the Australian continent and numerous southwest Pacific islands. We compared continental and island patterns of divergence using whole genome and morphological data. Australian mainland populations showed a low genetic population structure, lack of isolation by distance patterns and low morphological diagnosability, suggesting that the species' dispersal propensity in a continental setting is sufficient to overcome multiple forms of geographic barriers and large geographic distances. In contrast, except for island populations less than 200 years old, most island populations were highly genomically structured with clearer morphological diagnosability even if separated by relatively short geographic distances. The inferred reduction of dispersal propensity in island situations is consistent with the proposed model of great speciator formation on islands. Our phylogenomic analyses also allowed resolution of the silvereyes' evolutionary position, showing their relatively early emergence (similar to 1.5 Mya) within the rapidly radiating Zosteropidae, while population-level analyses demonstrated where morphological subspecies and genomic data align and disagree. However, the silvereye example also shows how uncertainties about relationships remain when reconstructing evolutionary history in rapidly radiating groups, even when whole genome data is available. Altogether, our results show how within-species genomic and morphological patterns measured over broad spatial scales and with varying geographic contexts can help reveal when particular stages of speciation such as great speciators are likely to emerge.
Details
- Title
- Islands Promote Diversification of the Silvereye Species Complex: A Phylogenomic Analysis of a Great Speciator
- Authors
- Andrea Estandia (Corresponding Author) - University of OxfordNilo Merino Recalde - University of OxfordAshley T. Sendell-Price - University of OxfordDominique A. Potvin - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringWilliam Goulding - Griffith UniversityBruce C. Robertson - University of OtagoSonya Clegg - University of Oxford
- Publication details
- Molecular Ecology, Vol.34(14), pp.1-16
- Publisher
- Wiley-Blackwell Publishing Ltd.
- Date published
- 2025
- DOI
- 10.1111/mec.17830
- ISSN
- 1365-294X
- PMID
- 40497404; PMC12237087
- Copyright note
- © 2025 The Author(s). Molecular Ecology published by John Wiley & Sons Ltd. 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.
- Data Availability
- Code to reproduce all analyses is available at https://github.com/andreaestandia/phylogeny_silvereye and https://github.com/nilomr/silvereye-morphology. Raw sequencing data are available at the NCBI Sequence Read Archive under BioProject PRJNA1264480, and VCF and BEAGLE files have been deposited in Dryad: https://doi.org/10.5061/dryad.vdncjsz69.
- Grant note
- A Marsden Fund grant (UOO1410) from the New Zealand Royal Society Te Apārangi awarded to BCR and SMC to support fieldwork on mainland Australia and Heron Island portions of the molecular work; National Geographic Society Committee for Research and Exploration Grant (9383-13) to SMC to support fieldwork in New Caledonia; Natural Environment Research Council (NERC) postdoctoral fellowship to SMC to support fieldwork in Vanuatu and New Caledonia; Heredity Fieldwork Grant from the Genetics Society to ATS-P and Percy Sladen Memorial Fund Grant (The Linnean Society) fund to SMC to support fieldwork in French Polynesia the Department of Zoology, and Oxford startup to SMC to support sequencing. ATS-P was supported by a NERC studentship (NE/L002612/1); AE was supported by a NERC studentship (NE/S007474/1) and a St John's College Graduate Scholarship.
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 991144503602621
- Output Type
- Journal article
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