Genetic differentiation in the circum—Antarctic sea spider Nymphon australe (Pycnogonida; Nymphonidae)

By C. Arango, A. Soler‐Membrives, K. Miller. 2011

91 citations recorded by the source corpus.

Nymphon australe Hodgson 1902 is the most abundant species of sea spiders in the Southern Ocean. The species is recognised as highly morphologically variable, circumpolar and eurybathic—which is surprising given that sea spiders lack a planktonic stage; the fertilised eggs and larvae remain attached to the ovigers of the father, and consequently have limited dispersal capacity. In this study, we investigate the genetic structure of N. australe populations around Antarctica, confronting the apparent limited dispersal ability with its recognised circumpolarity. Here we analyse mitochondrial DNA of specimens from Antarctic Peninsula, Weddell Sea and East Antarctica to determine if they represent populations of the widespread N. australe — or instead we can recognise cryptic species – and how genetically different they are. Both CO1 and 16S sequence data produced single haplotype networks for N. australe from all three Antarctic locations without indication of cryptic speciation. However, we found strong phylogeographic structure among the three Antarctic locations based on CO1 data. There was only a single shared haplotype between the Antarctic Peninsula and the East Antarctica locations, and all three regions were significantly subdivided from each other (FST=0.28, p<0.01). Furthermore, within the Antarctic Peninsula and East Antarctic locations, we found evidence of genetic subdivision between populations of N. australe separated by 10–100 s of km (FST=0.07–0.22, p<0.05), consistent with sea spiders life history traits indicating a limited dispersal capability. We conclude N. australe represents a single circum-Antarctic species that, despite its limited dispersal abilities, has successfully colonised large parts of the Antarctic marine ecosystem through geological history. However, clear genetic differences among and within locations indicate contemporary gene flow is limited, and that populations of N. australe around Antarctica are effectively isolated.

Subfields: Genetics, Nature and Landscape Conservation, Oceanography

View Paper: https://www.semanticscholar.org/paper/7a9f8d7bc74bc5be65de1170756c53e06dd5c6f7

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In Genetics

In Nature and Landscape Conservation

In Oceanography

Citations in the corpus

Biogeographic Atlas of the Southern Ocean (2014, background): “Arango et al. (2011) found Nymphon australe to be a single circumpolar species, with prominent geographic genetic differences suggesting limited or no ongoing gene flow between regions.”
Patterns, processes and vulnerability of Southern Ocean benthos: a decadal leap in knowledge and understanding (2013, background): “…evolutionary lineages and across a range of Southern Ocean locations (e.g., gastropods: Wilson et al. 2009, pycnogonids: Krabbe et al. 2010; Arango et al. 2011; isopods: Held and Wägele 2005; Raupach et al. 2009; amphipods: Lörz et al. 2009; Havermans et al. 2010; ostracods: Brandão et…”
Biodiversity and phylogeography of Arctic marine fauna: insights from molecular tools (2011, background): “Similar incidences of cryptic species complexes have also been uncovered in several widespread Antarctic taxa (e.g., crinoids, Wilson et al. 2007; sea spiders, Krabbe et al. 2010; Arango et al. 2010; octopus, Allcock et al. 2010; Allcock et al., in review).”