TY - JOUR

T1 - Survivors and colonizers

T2 - Contrasting biogeographic histories reconciled in the Antarctic freshwater copepod Boeckella poppei

AU - Maturana, Claudia S.

AU - Biersma, Elisabeth M.

AU - Díaz, Angie

AU - González-Wevar, Claudio

AU - Contador, Tamara

AU - Convey, Peter

AU - Jackson, Jennifer A.

AU - Poulin, Elie

N1 - Funding Information: This work was funded by ANID—Millennium Science Initiative Program—ICN2021_002, ANID/BASAL FB210018 from Cape Horn International Centre (CHIC), and Grant ANID ACE210006 from the Institute of Ecology and Biodiversity (IEB). Postdoctoral grant 3210063 to CSM and NERC core funding to the BAS ‘Ecosystems’ and ‘Biodiversity, Evolution and Adaptation’ Teams to JJ, PC, and EB. EB was also funded by NERC-CONICYT grant NE/P003079/1 and Carlsberg Foundation grant CF18-0267. Funding Information: We recognize the Chilean Antarctic Institute (INACH) for the logistic support during the Chilean Antarctic Expeditions (ECA 53, 54, and 55), the South Atlantic Environmental Research Institute (SAERI) for their logistic support of sampling in the Falkland/Malvinas Islands and South Georgia, and Laboratorio de Ecosistemas Marinos Antárticos y Subantárticos (LEMAS) for their constant support of our fieldwork in Punta Arenas and Tierra del Fuego. Finally, CSM would like to particularly thank Moisés Valladares, Zambra López, Karin Gérard, and Sebastian Rosenfeld for valuable sampling, discussion, and support in the development of this study. Publisher Copyright: Copyright © 2022 Maturana, Biersma, Diaz, Gonzalez-Wevar, Contador, Convey, Jackson and Poulin.

PY - 2022

Y1 - 2022

N2 - Two main hypotheses have been proposed to explain the contemporary distribution of Antarctic terrestrial biota. We assess whether the current distribution of maritime Antarctic populations of the freshwater copepod Boeckella poppei is the result of (1) a post-Last Glacial Maximum (LGM) colonization, or whether (2) the species survived in regional glacial refugia throughout the LGM and earlier glaciations. Using 438 specimens from 34 different sampling sites across Southern South America, South Georgia, South Orkney Islands, South Shetland Islands, and the Antarctic Peninsula, we analyzed mitochondrial and nuclear sequences to uncover patterns of genetic diversity and population structure. We also performed median-joining haplotype network, phylogenetic reconstruction, and divergence time analyses. Finally, we evaluated past demographic changes and historical scenarios using the Approximate Bayesian Computation (ABC) method. Our data support the existence of two clades with different and contrasting biogeographic histories. The first clade has been present in maritime Antarctica since at least the mid-Pleistocene, with the South Orkney Islands the most likely refugial area. The second clade has a broader distribution including southern South America, South Georgia, South Shetland Islands, and the Antarctic Peninsula. The ABC method identified long-distance dispersal (LDD) colonization event(s) from southern South America to South Georgia and the maritime Antarctic after the LGM deglaciation, supporting more recent colonization of Antarctic locations. The current Antarctic and sub-Antarctic distribution of B. poppei is likely derived from two independent biogeographic events. The combination of both (1) post-LGM colonization from southern South America and (2) longer-term persistence in in situ regional refugia throughout glacial periods challenges current understanding of the biogeographic history of Antarctic freshwater biota. Re-colonization of ice-impacted Antarctic areas would have occurred following a LDD and Establishment model, pointing to the existence of possible post-dispersal barriers, despite widely assumed high passive dispersal capacity in freshwater invertebrates.

AB - Two main hypotheses have been proposed to explain the contemporary distribution of Antarctic terrestrial biota. We assess whether the current distribution of maritime Antarctic populations of the freshwater copepod Boeckella poppei is the result of (1) a post-Last Glacial Maximum (LGM) colonization, or whether (2) the species survived in regional glacial refugia throughout the LGM and earlier glaciations. Using 438 specimens from 34 different sampling sites across Southern South America, South Georgia, South Orkney Islands, South Shetland Islands, and the Antarctic Peninsula, we analyzed mitochondrial and nuclear sequences to uncover patterns of genetic diversity and population structure. We also performed median-joining haplotype network, phylogenetic reconstruction, and divergence time analyses. Finally, we evaluated past demographic changes and historical scenarios using the Approximate Bayesian Computation (ABC) method. Our data support the existence of two clades with different and contrasting biogeographic histories. The first clade has been present in maritime Antarctica since at least the mid-Pleistocene, with the South Orkney Islands the most likely refugial area. The second clade has a broader distribution including southern South America, South Georgia, South Shetland Islands, and the Antarctic Peninsula. The ABC method identified long-distance dispersal (LDD) colonization event(s) from southern South America to South Georgia and the maritime Antarctic after the LGM deglaciation, supporting more recent colonization of Antarctic locations. The current Antarctic and sub-Antarctic distribution of B. poppei is likely derived from two independent biogeographic events. The combination of both (1) post-LGM colonization from southern South America and (2) longer-term persistence in in situ regional refugia throughout glacial periods challenges current understanding of the biogeographic history of Antarctic freshwater biota. Re-colonization of ice-impacted Antarctic areas would have occurred following a LDD and Establishment model, pointing to the existence of possible post-dispersal barriers, despite widely assumed high passive dispersal capacity in freshwater invertebrates.

KW - Antarctic-Magellan connection

KW - centropagidae

KW - last glacial maximum

KW - monopolization hypothesis

KW - phylogeography

KW - refugia

U2 - 10.3389/fevo.2022.1012852

DO - 10.3389/fevo.2022.1012852

M3 - Journal article

AN - SCOPUS:85144012782

VL - 10

JO - Frontiers in Ecology and Evolution

JF - Frontiers in Ecology and Evolution

SN - 2296-701X

M1 - 1012852

ER -