DOI: 10.5281/zenodo.14719348
title: Genbank Accession Numbers of Seven snail species hidden in one: Biogeographic diversity in an apparently widespread periwinkle in the Southern Ocean

description: This dataset contains GenBank accession numbers for 45 cytochrome c oxidase subunit I (COI) genes and 94 large subunit ribosomal RNA (28S rRNA) genes obtained from periwinkle snail species Laevilitorina caliginosa, Laevilacunaria antarctica, Laevilitorina umbilicata, and Laevilitorina claviformis
description: Aim

The Antarctic Circumpolar Current imparts significant structure to the Southern Ocean biota. The Antarctic Polar Front is a major barrier to dispersal, with separate species (or sometimes intraspecific clades) normally occurring either side of this feature. We examined the biogeographic structure of an apparent exception to this rule in a widespread genus of the Southern Ocean, the periwinkle snail, Laevilitorina.

Location

Southern Ocean.

Taxon

Littorinidae, Laevilitorininae, Laevilitorina.

Methods

Using 750 specimens from 16 Southern Ocean Laevilitorina populations across >8000 km, we analysed mitochondrial COI and nuclear 28S sequences to uncover the evolutionary history of these marine near-shore snails. We utilized multi-locus phylogenetic reconstructions, species-delimitation analyses, divergence-time estimations and geometric morphometrics.

Results

Molecular data revealed that the widespread nominal species L. caliginosa comprises seven species-level clades, all supported by morphological data, whereas the Antarctic nominal species L. antarctica, L. claviformis and L. umbilicata are conspecific. Six “caliginosa” clades are restricted to southern South America, but one lineage extends from Antarctica to distant sub-Antarctic islands on both sides of the APF. Geometric morphometrics also identified significant differences among these clades, but uncoupled from genetic differentiation.

Main conclusions

The apparent trans-APF distribution of the poorly dispersing Laevilitorina caliginosa is largely illusory: this taxon consists of at least seven discrete species, only one of which has a trans-APF distribution. Similar to most Laevilitorina species, the remaining six “caliginosa” clades are narrow endemics. Biogeographical patterns in Laevilitorina reflect the role of vicariance associated with geological processes together with recent long-distance dispersal events. Laevilitorina originated near the Eocene/Oligocene boundary and diversified during the Miocene and the Pliocene. Laevilitorina is not a cryptic-species complex: speciation was accompanied by hitherto unrecognized morphological differentiation. This study represents the most detailed molecular work on Southern-Ocean littorinids and reveals unforeseen diversity across this globally important region.
description: Many thanks to Angie Díaz, Karin Gérard, Andreas Schmider, Yarleth Poveda, for field assistance and samplings in southern South America and the Antarctic Peninsula. Many thanks to the Antarctic Circumnavigation Expedition (carried out by the Swiss Polar Institute, supported by the ACE Foundation and Ferring Pharmaceuticals). Alex Hickling, Javier Naretto and Rebecca Cumming are thanked for their field assistance while Lisa Kirkendale and Corey Whisson are thanked for their assistance with loans from the Western Australian Museum (WAM).

South American specimens were captured under the Chilean legislation (Technical Memorandum P.INV N° 258/ 2021 SUBPESCA). Field access facilities to Crozet and Kerguelen Islands were supported by the French Polar Institute-IPEV (program n°1044-Proteker) and the LTSER Zone Atelier Antarctique et Subantarctique (ZATA), France. We are grateful to the support of the South Atlantic Environmental Research Institute and the Shallow Marine Surveys Group of the collection of Laevilitorina samples in the Falkland Islands. Field access facilities to South Georgia was supported by the British Antarctic Survey (BAS) and the collected specimens were authorized under the permit number 2017/058 to C.S.M. BAS is supported by core funds from UKRI-NERC to the BEA Team.