An ancient, Antarctic-specific species complex: large divergences between multiple Antarctic lineages of the tardigrade genus Mesobiotus.

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Publisher: Elsevier B.V.
Document Type: Brief article
Length: 390 words

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Abstract :

Highlights * Antarctic species of Mesobiotus are strongly divergent from other Mesobiotus species. * Widely used taxonomic species groups "Furciger" and "Harmsworthi" have no systematic support. * Mesobiotus has radiated in Antarctica since it was isolated from other continents. * First pan-Antarctic study of a specific tardigrade group. Abstract Antarctica has been isolated and progressively glaciated for over 30 million years, with only approximately 0.3 % of its area currently ice-free and capable of supporting terrestrial ecosystems. As a result, invertebrate populations have become isolated and fragmented, in some cases leading to speciation. Terrestrial invertebrate species currently found in Antarctica often show multi-million year, and even Gondwanan, heritage, with little evidence of recent colonisation. Mesobiotus is a globally distributed tardigrade genus. It has commonly been divided into two "groups", referred to as harmsworthi and furciger, with both groups currently considered cosmopolitan, with global reports including from both the Arctic and the Antarctic. However, some authors considered that Meb. furciger, as originally described, may represent an Antarctic-specific lineage. Using collections of tardigrades from across the Antarctic continent and publicly available sequences obtained from online databases, we use mitochondrial and nuclear ribosomal sequence data to clarify the relationships of Antarctic Mesobiotus species. Our analyses show that all Antarctic members belong to a single lineage, evolving separately from non-Antarctic representatives. Within this Antarctic lineage there are further deep divisions among geographic regions of the continent, consistent with the presence of a species complex. Based on our data confirming the deep divisions between this Antarctic lineage, which includes representatives of both groups, we recommend that the use of furciger and harmsworthi group terminology is now abandoned, as it leads to systematic and biogeographical confusion. Author Affiliation: (a) British Antarctic Survey, NERC, High Cross, Madingley Rd, Cambridge CB3 0ET, UK (b) University of Bristol, School of Biological Sciences and Earth Sciences, 24 Tyndall Avenue, Bristol BS8 1TQ, UK (c) Securing Antarctica's Environmental Future, Earth and Biological Sciences, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia (d) School of Biological Sciences, University of Adelaide, SA 5005, Australia (e) Department of Zoology, University of Johannesburg, Auckland Park 2006, South Africa * Corresponding author. Article History: Received 20 July 2021; Revised 7 January 2022; Accepted 10 January 2022 Byline: K.A. Short (a,b), C.J. Sands (a,*), S.J. McInnes (a), D. Pisani (b), M.I. Stevens (c,d), P. Convey (a,e)

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Gale Document Number: GALE|A699113558