Abstract
BackgroundThe approximately 350 demosponge species that have been described from Antarctica represent a faunistic component distinct from that of neighboring regions. Sponges provide structure to the Antarctic benthos and refuge to other invertebrates, and can be dominant in some communities. Despite the importance of sponges in the Antarctic subtidal environment, sponge DNA barcodes are scarce but can provide insight into the evolutionary relationships of this unique biogeographic province.Methodology/Principal FindingsWe sequenced the standard barcoding COI region for a comprehensive selection of sponges collected during expeditions to the Ross Sea region in 2004 and 2008, and produced DNA-barcodes for 53 demosponge species covering about 60% of the species collected. The Antarctic sponge communities are phylogenetically diverse, matching the diversity of well-sampled sponge communities in the Lusitanic and Mediterranean marine provinces in the Temperate Northern Atlantic for which molecular data are readily available. Additionally, DNA-barcoding revealed levels of in situ molecular evolution comparable to those present among Caribbean sponges. DNA-barcoding using the Segregating Sites Algorithm correctly assigned approximately 54% of the barcoded species to the morphologically determined species.Conclusion/SignificanceA barcode library for Antarctic sponges was assembled and used to advance the systematic and evolutionary research of Antarctic sponges. We provide insights on the evolutionary forces shaping Antarctica's diverse sponge communities, and a barcode library against which future sequence data from other regions or depth strata of Antarctica can be compared. The opportunity for rapid taxonomic identification of sponge collections for ecological research is now at the horizon.
Highlights
IntroductionIn some cases, dominant members of the rich invertebrate communities that inhabit the Antarctic shelf [1,2,3,4]
Sponges are conspicuous and, in some cases, dominant members of the rich invertebrate communities that inhabit the Antarctic shelf [1,2,3,4]
Hadromerida contains two major clades, the first containing Sphaerotylus antarcticus Kirkpatrick, Polymastia isidis Thiele, and P. invaginata Kirkpatrick (Polymastiidae), and Tentorium papillatum (Kirkpatrick) (Suberitidae) and Polymastia sequences harvested from GenBank, and the second containing predominantly Suberitidae genera Homaxinella, Pseudosuberites, Plicatellopsis, together with Stylocordyla (Stylocordylidae), and with halichondrid sequences harvested from GenBank
Summary
In some cases, dominant members of the rich invertebrate communities that inhabit the Antarctic shelf [1,2,3,4]. In terms of species richness, Antarctic sponge assemblages are comparable to some tropical faunas (e.g. the western Indian Ocean, the Caribbean Sea [10]). The approximately 350 sponge species reported from the Antarctic shelf to date constitute a distinct faunistic assemblage characterized by its high species-level endemism and generic cosmopolitanism [3,11]. The high endemicity levels observed among Antarctic sponges have been hypothesized to be the result of the continent's and surrounding oceans' geological history and prolonged geographic isolation [3,11]. Sponges provide structure to the Antarctic benthos and refuge to other invertebrates, and can be dominant in some communities. Despite the importance of sponges in the Antarctic subtidal environment, sponge DNA barcodes are scarce but can provide insight into the evolutionary relationships of this unique biogeographic province
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