Invertebrate Systematics Invertebrate Systematics Society
Systematics, phylogeny and biogeography
RESEARCH ARTICLE

Mitochondrial DNA analyses reveal widespread tardigrade diversity in Antarctica

Alejandro Velasco-Castrillón A K , Sandra J. McInnes B , Mark B. Schultz C , María Arróniz-Crespo D , Cyrille A. D’Haese E , John A. E. Gibson F , Byron J. Adams G , Timothy J. Page H , Andrew D. Austin A , Steven J. B. Cooper A I and Mark I. Stevens I J
+ Author Affiliations
- Author Affiliations

A Australian Centre for Evolutionary Biology and Biodiversity, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.

B British Antarctic Survey, Madingley Road, Cambridge, Cambridgeshire, CB3 0ET, United Kingdom.

C Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Vic. 3010, Australia.

D Bangor University, School of Environment, Natural Resources and Geography, 2nd Floor ECW, Bangor, Gwynedd, LL57 2UW, United Kingdom.

E UMR 7205 CNRS, Origine, Structure et Evolution de la Biodiversite, Departement Systematique et Evolution, Museum National d’Histoire Naturelle, CP50, Entomologie, 75231 Paris Cedex 05, France.

F Institute of Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tas. 7001, Australia.

G Department of Biology, and Evolutionary Ecology Laboratories, Brigham Young University, Provo, UT 84602, USA.

H Australian Rivers Institute, Nathan campus, Griffith University, 170 Kessels Road, Nathan, QLD 4111, Australia.

I South Australian Museum, North Terrace, Adelaide, SA 5000, Australia.

J School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia.

K Corresponding author. Email: a.velascocastrillon@gmail.com

Invertebrate Systematics 29(6) 578-590 https://doi.org/10.1071/IS14019
Submitted: 8 April 2015  Accepted: 15 September 2015   Published: 22 December 2015

Abstract

Antarctica contains some of the most challenging environmental conditions on the planet due to freezing temperatures, prolonged winters and lack of liquid water. Whereas 99.7% of Antarctica is permanently covered by ice and snow, some coastal areas and mountain ridges have remained ice-free and are able to sustain populations of microinvertebrates. Tardigrades are one of the more dominant groups of microfauna in soil and limno-terrestrial habitats, but little is known of their diversity and distribution across Antarctica. Here, we examine tardigrades sampled from across an extensive region of continental Antarctica, and analyse and compare their partial mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequences with those from the Antarctic Peninsula, maritime and sub-Antarctica, Tierra del Fuego and other worldwide locations in order to recognise operational taxonomic units (OTUs). From 439 new tardigrade COI sequences, we identified 98 unique haplotypes (85 from Antarctica) belonging to Acutuncus, Diphascon, Echiniscus, Macrobiotus, Milnesium and unidentified Parachela. Operational taxonomic units were delimited by Poisson tree processes and general mixed Yule coalescent methods, resulting in 58 and 55 putative species, respectively. Most tardigrades appear to be locally endemic (i.e. restricted to a single geographic region), but some (e.g. Acutuncus antarcticus (Richters, 1904)) are widespread across continental Antarctica. Our molecular results reveal: (i) greater diversity than has previously been appreciated with distinct OTUs that potentially represent undescribed species, and (ii) a lack of connectivity between most OTUs from continental Antarctica and those from other Antarctic geographical zones.

Additional keywords: biodiversity, biogeography, COI gene, cosmopolitan, endemic, OTUs, refugia, species delimitation, Tardigrada.


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