Sherlock, Miranda B;
Wlikinson, Mark;
Maddock, Simon T;
Nussbaum, Ronald A;
Day, Julia J;
Streicher, Jeffrey W;
(2025)
Submerged corridors of ancient gene flow in an island amphibian.
Molecular Ecology
, 34
(9)
, Article e17742. 10.1111/mec.17742.
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Abstract
Many island archipelagos sit on shallow continental shelves, and during the Pleistocene these islands were often connected as global sea levels dropped following glaciation. Given a continental shelf only 30–60 m below sea level, the terrestrial biota of the Seychelles Archipelago likely dispersed amongst now isolated islands during the Pleistocene. Hypogeophis rostratus is an egg-laying, direct-developing caecilian amphibian found on ten islands in the granitic Seychelles. Despite the seemingly limited dispersal abilities of this salt-intolerant amphibian its distribution on multiple islands suggests likely historic dispersal across now submerged continental shelf corridors. We tested for the genetic signature of these historic corridors using fine-scale genomic data (ddRADseq). We found that genomic clusters often did not correspond to islands in the archipelago and that isolation-by-distance patterns were more consistent with gene flow across a continuous landscape than with isolated island populations. Using effective migration surfaces and ancestral range expansion prediction we found support for contemporary populations originating near the large southern island of Mahé and dispersing to northern islands via the isolated Frégate island, with additional historic migration across the flat expanse of the Seychelles bank. Collectively, our results suggest that biogeographic patterns can retain signals from Pleistocene ‘palaeo-islands’, and that present-day islands can be thought of as hosting bottlenecks or transient refugia rather than discrete genetic units. Thus, the signatures of gene flow associated with palaeo-islands may be stronger than the isolating effects of contemporary islands in terrestrial species distributed on continental shelf islands.
| Type: | Article |
|---|---|
| Title: | Submerged corridors of ancient gene flow in an island amphibian |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1111/mec.17742 |
| Publisher version: | https://doi.org/10.1111/mec.17742 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Caecilian, ddRADseq, gene flow, Indian Ocean, island biogeography |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Genetics, Evolution and Environment |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10206074 |
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