Gene flow in the Antarctic bivalveAequiyoldia eightsii(Jay, 1839) suggests a role for the Antarctic Peninsula Coastal Current in larval dispersal

Abstract

The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.

Guiding marine protected area network design with comparative phylogeography and population genomics: An exemplary case from the Southern Ocean

“…In this case, migration may be facilitated by the Antarctic Peninsula Coastal Current (APCC) and the Antarctic Circumpolar Current (ACC), as described for D. antarctica (see Leiva et al, 2019) and Aequiyoldia eightsii (see Muñoz-Ramírez et al, 2020).…”

Mitochondrial Heteroplasmy and PCR Amplification Bias Lead to Wrong Species Delimitation with High Confidence in the South American and Antarctic Marine Bivalve Aequiyoldia eightsii Species Complex

“…This wide distribution range on both sides of the Drake Passage has given rise to several revisions of its taxonomic status [ 25 ]. Recently, Muñoz-Ramírez et al [ 26 ] highlighted the role of the Antarctic circumpolar current as a biogeographic barrier between the Antarctic Peninsula and South America, confirming the existence of two different species across the Drake Passage, which, according to Martínez et al [ 27 ], have different levels of susceptibility to two major climate change stressors, namely, temperature shifts and hypoxia. González-Wevar et al [ 28 ] suggested the presence of several cryptic species comprising two lineages along the Antarctic Peninsula (5.78% COI p-distance), a third linage in South America (6.5–7.5% COI and 1.2% ITS p-distances) with respect to the Antarctic peninsula, and two additional mitochondrial lineages on Kerguelen Island and the Falkland/Malvinas Islands.…”

A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression in South American and Antarctic Aequiyoldia bivalves

“…eightsii but emphasize that Antarctic and South American populations are likely different, but closely related species awaiting formal taxonomic recognition. Recently, Muñoz-Ramírez et al (2020) highlighted based on genomic data the role of the Antarctic Circumpolar Current as a biogeographic barrier to larval transport between both continents, preventing or strongly reducing the potential for genetic connectivity between Antarctic and South American Aequiyoldia lineages. A hypothetical crossing of Aequiyoldia across Drake Passage is then more likely to be caused by ships as larvae in ballast water.…”