Phylogeography of the Antarctic planktotrophic brittle star Ophionotus victoriae reveals genetic structure inconsistent with early life history

Previous studies on Ophiothrix in European waters demonstrated the existence of two distinct species, Ophiothrix fragilis and Ophiothrix sp. II. Using phylogenetic and species delimitation techniques based on two mitochondrial genes (cytochrome c oxidase I and 16S rRNA) we prove the existence of a new congeneric species (Ophiothrix sp. III), occurring in the deep Atlantic coast of the Iberian Peninsula and the Alboran Sea. We compared phylogeographic patterns of these three Ophiothrix species to test whether closely related species are differentially affected by past demographic events and current oceanographic barriers. We used 432 sequences (137 of O. fragilis, 215 of Ophiothrix sp. II, and 80 of Ophiothrix sp. III) of the 16S rRNA from 23 Atlantic-Mediterranean locations for the analyses. We observed different geographic and bathymetric distributions, and contrasted phylogeography among species. Ophiothrix fragilis appeared genetically isolated between the Atlantic and Mediterranean basins, attributed to past vicariance during Pleistocene glaciations and a secondary contact associated to demographic expansion. This contrasts with the panmixia observed in Ophiothrix sp. II across the Atlantic-Mediterranean area. Results were not conclusive for Ophiothrix sp. III due to the lack of a more complete sampling within the Mediterranean Sea.

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“…refs 24 and 29, although they showed different phylogeographic patterns. Panmixia in the shallow-water Ophiothrix sp.…”

Section: Discussionmentioning

confidence: 92%

Contrasted phylogeographic patterns on mitochondrial DNA of shallow and deep brittle stars across the Atlantic-Mediterranean area

Taboada

Pérez‐Portela

2016

Sci Rep

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“…These include previously unrecognized genetic diversity with restricted distributions in the starfish Odontaster validus (Janosik and Halanych, 2010;Janosik et al, 2011), the crinoid Promachocrinus kerguelensis (Hemery et al, 2012), and the brittle stars Ophionotus victoriae (Hunter and Halanych, 2010), Astrotoma agassizii (Hunter and Halanych, 2008), and Ophiura lymani (Sands et al, 2015). Such genetic divergence seems to be enhanced by the occurrence of the Polar Front and the geographic barrier of the Drake Passage, which separates Antarctica from South America and spans approximately 900 km, reaching ca.…”

Section: Echinodermsmentioning

confidence: 93%

Evolutionary patterns in Antarctic marine invertebrates: An update on molecular studies

2015

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“…Upon collection, samples were morphologically examined (mainly by MPG, CJS, and KMH) to verify species designations as described (McKnight, ; Sieg & Waegele, ). Oceanic island samples used in Hunter and Halanych () were kindly made available from the NSF IceFish cruise and W. Deitrich (OPP‐0132032). In total, the mitochondrial dataset included 414 specimens over 88 sampling localities that span the Ross, Amundsen, Bellingshausen, Antarctic Peninsula, Weddell Seas and oceanic islands, or a geographic distance of >7,000 km (Figure and Table S1).…”

Section: Methodsmentioning

confidence: 99%

Geographic structure in the Southern Ocean circumpolar brittle star Ophionotus victoriae (Ophiuridae) revealed from mtDNA and single‐nucleotide polymorphism data

Galaska

Sands

Santos

et al. 2016

Ecology and Evolution

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Marine systems have traditionally been thought of as “open” with few barriers to gene flow. In particular, many marine organisms in the Southern Ocean purportedly possess circumpolar distributions that have rarely been well verified. Here, we use the highly abundant and endemic Southern Ocean brittle star Ophionotus victoriae to examine genetic structure and determine whether barriers to gene flow have existed around the Antarctic continent. Ophionotus victoriae possesses feeding planktotrophic larvae with presumed high dispersal capability, but a previous study revealed genetic structure along the Antarctic Peninsula. To test the extent of genetic differentiation within O. victoriae, we sampled from the Ross Sea through the eastern Weddell Sea. Whereas two mitochondrial DNA markers (16S rDNA and COI) were employed to allow comparison to earlier work, a 2b‐RAD single‐nucleotide polymorphism (SNP) approach allowed sampling of loci across the genome. Mitochondrial data from 414 individuals suggested three major lineages, but 2b‐RAD data generated 1,999 biallelic loci that identified four geographically distinct groups from 89 samples. Given the greater resolution by SNP data, O. victoriae can be divided into geographically distinct populations likely representing multiple species. Specific historical scenarios that explain current population structure were examined with approximate Bayesian computation (ABC) analyses. Although the Bransfield Strait region shows high diversity possibly due to mixing, our results suggest that within the recent past, dispersal processes due to strong currents such as the Antarctic Circumpolar Current have not overcome genetic subdivision presumably due to historical isolation, questioning the idea of large open circumpolar populations in the Southern Ocean.

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Phylogeography of the Antarctic planktotrophic brittle star Ophionotus victoriae reveals genetic structure inconsistent with early life history

Cited by 30 publications

References 83 publications

Contrasted phylogeographic patterns on mitochondrial DNA of shallow and deep brittle stars across the Atlantic-Mediterranean area

Contrasted phylogeographic patterns on mitochondrial DNA of shallow and deep brittle stars across the Atlantic-Mediterranean area

Evolutionary patterns in Antarctic marine invertebrates: An update on molecular studies

Geographic structure in the Southern Ocean circumpolar brittle star Ophionotus victoriae (Ophiuridae) revealed from mtDNA and single‐nucleotide polymorphism data

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