Genomic insights of evolutionary divergence and life histories innovations in Antarctic brittle stars

Lau, Sally C.Y., Strugnell, Jan M., Sands, Chester J., Silva, Catarina N.S., and Wilson, Nerida G. (2023) Genomic insights of evolutionary divergence and life histories innovations in Antarctic brittle stars. Molecular Ecology, 32 (13). pp. 3382-3402.

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Understanding the drivers of evolutionary innovation provides a crucial perspective of how evolutionary processes unfold across taxa and ecological systems. It has been hypothesised that the Southern Ocean provided ecological opportunities for novelty in the past. However, the drivers of innovation are challenging to pinpoint as the evolutionary genetics of Southern Ocean fauna are influenced by Quaternary glacial–interglacial cycles, oceanic currents and species ecology. Here we examined the genome-wide single nucleotide polymorphisms of the Southern Ocean brittle stars Ophionotus victoriae (five arms, broadcaster) and O. hexactis (six arms, brooder). We found that O. victoriae and O. hexactis are closely-related species with interspecific gene flow. During the late Pleistocene, O. victoriae likely persisted in a connected deep water refugium and in situ refugia on the Antarctic continental shelf and around Antarctic islands; O. hexactis persisted exclusively within in situ island refugia. Within O. victoriae, contemporary gene flow linking to the Antarctic Circumpolar Current, regional gyres and other local oceanographic regimes was observed. Gene flow connecting West and East Antarctic islands near the Polar Front was also detected in O. hexactis. A strong association was detected between outlier loci and salinity in O. hexactis. Both O. victoriae and O. hexactis are associated with genome-wide increase in alleles at intermediate-frequencies; the alleles associated with this peak appear to be species specific, and these intermediate-frequency variants are far more excessive in O. hexactis. We hypothesise that the peak in alleles at intermediate frequencies could be related to adaptation in the recent past, linked to evolutionary innovations of increase in arm number and a switch to brooding from broadcasting, in O. hexactis.

Item ID: 79069
Item Type: Article (Research - C1)
ISSN: 1365-294X
Keywords: echinoderms, life history evolution, molecular evolution, population genetics-empirical
Copyright Information: This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2023 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.
Date Deposited: 21 Dec 2023 00:49
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310405 Evolutionary ecology @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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