Evolutionary innovations in Antarctic brittle stars linked to glacial refugia

Lau, Sally C.Y., Strugnell, Jan M., Sands, Chester J., Silva, Catarina N.S., and Wilson, Nerida G. (2021) Evolutionary innovations in Antarctic brittle stars linked to glacial refugia. Ecology and Evolution, 11 (23). pp. 17428-17446.

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Abstract

The drivers behind evolutionary innovations such as contrasting life histories and morphological change are central questions of evolutionary biology. However, the environmental and ecological contexts linked to evolutionary innovations are generally unclear. During the Pleistocene glacial cycles, grounded ice sheets expanded across the Southern Ocean continental shelf. Limited ice-free areas remained, and fauna were isolated from other refugial populations. Survival in Southern Ocean refugia could present opportunities for ecological adaptation and evolutionary innovation. Here, we reconstructed the phylogeographic patterns of circum-Antarctic brittle stars Ophionotus victoriae and O. hexactis with contrasting life histories (broadcasting vs brooding) and morphology (5 vs 6 arms). We examined the evolutionary relationship between the two species using cytochrome c oxidase subunit I (COI) data. COI data suggested that O. victoriae is a single species (rather than a species complex) and is closely related to O. hexactis (a separate species). Since their recent divergence in the mid-Pleistocene, O. victoriae and O. hexactis likely persisted differently throughout glacial maxima, in deep-sea and Antarctic island refugia, respectively. Genetic connectivity, within and between the Antarctic continental shelf and islands, was also observed and could be linked to the Antarctic Circumpolar Current and local oceanographic regimes. Signatures of a probable seascape corridor linking connectivity between the Scotia Sea and Prydz Bay are also highlighted. We suggest that survival in Antarctic island refugia was associated with increase in arm number and a switch from broadcast spawning to brooding in O. hexactis, and propose that it could be linked to environmental changes (such as salinity) associated with intensified interglacial-glacial cycles.

Item ID: 71164
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: contrasting life histories, evolutionary innovation, glacial refugia, morphological innovation, population genetics
Copyright Information: 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. © 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Additional Information:

All newly generated COI sequences were deposited to GenBank at NCBI under accession numbers MZ543435—MZ543949.

Funders: National Science Foundation (USA) Office of Polar Programs, Antarctic Circumnavigation Expedition, Australian Research Council (ARC), Australian Academy of Science, David Pearse bequest, Antarctic Science Foundation
Projects and Grants: Scientific Committee on Antarctic Research (SCAR) program State of the Antarctic Ecosystem (Ant-Eco), ARC Discovery grant DP190101347, ARC SRIEAS Grant SR200100005 Securing Antarctica's Environmental Future
Date Deposited: 19 Dec 2021 22:08
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310402 Biogeography and phylogeography @ 50%
31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310405 Evolutionary ecology @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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