BackgroundA range of higher animal taxa are shared across various chemosynthesis-based ecosystems (CBEs), which demonstrates the evolutionary link between these habitats, but on a global scale the number of species inhabiting multiple CBEs is low. The factors shaping the distributions and habitat specificity of animals within CBEs are poorly understood, but geographic proximity of habitats, depth and substratum have been suggested as important. Biogeographic studies have indicated that intermediate habitats such as sedimented vents play an important part in the diversification of taxa within CBEs, but this has not been assessed in a phylogenetic framework. Ampharetid annelids are one of the most commonly encountered animal groups in CBEs, making them a good model taxon to study the evolution of habitat use in heterotrophic animals. Here we present a review of the habitat use of ampharetid species in CBEs, and a multi-gene phylogeny of Ampharetidae, with increased taxon sampling compared to previous studies.ResultsThe review of microhabitats showed that many ampharetid species have a wide niche in terms of temperature and substratum. Depth may be limiting some species to a certain habitat, and trophic ecology and/or competition are identified as other potentially relevant factors. The phylogeny revealed that ampharetids have adapted into CBEs at least four times independently, with subsequent diversification, and shifts between ecosystems have happened in each of these clades. Evolutionary transitions are found to occur both from seep to vent and vent to seep, and the results indicate a role of sedimented vents in the transition between bare-rock vents and seeps.ConclusionThe high number of ampharetid species recently described from CBEs, and the putative new species included in the present phylogeny, indicates that there is considerable diversity still to be discovered. This study provides a molecular framework for future studies to build upon and identifies some ecological and evolutionary hypotheses to be tested as new data is produced.Electronic supplementary materialThe online version of this article (10.1186/s12862-017-1065-1) contains supplementary material, which is available to authorized users.
Alvestad, T., Kongsrud, J.A. and Kongshavn, K. 2014. Ampharete undecima, a new deep-sea ampharetid (Annelida, Polychaeta) from the Norwegian Sea. Memoirs of Museum Victoria 71: 11-19.Ampharete undecima, a new deep-sea polychaete belonging to the family Ampharetidae, is described from slope depths in the Norwegian Sea. The new species is of small size, up to 5 mm long and 0.5 mm wide, and thus it may have been overlooked in previous studies. It is shown to be a common and widespread species in the Nordic Seas in depths ranging from 600-1650 m. The new species is referred to the genus Ampharete based on characteristics of the prostomium, the presence of buccal tentacles with secondary pinnulae, four pairs of branchiae arising from fused segment II + III, 12 thoracic uncinigerous segments, and a single pair of nephridial papillae on segment IV. The new species differs from all known species of Ampharete in having 11 rather than 12-28 abdominal uncinigerous segments.
Not much is known on polychaete diversity in the deep Nordic Seas. Based on data from extensive sampling over three decades, new data on polychaetes covering depths from 550 m to 3,800 m are presently reported. On a depth gradient, the number of polychaete families gradually declined from 35 at the upper slope (500-750 m) to 11 at 3,800 m. Species diversity in eight polychaete families subjected to critical taxonomic studies showed a gradual decrease from a diverse group of slope species in the upper and middle slope (500-1,000 m) to a species poor fauna in the deepest areas (> 3,000 m), with a distinct break at about 2,000 m. Faunal changes were documented both at alpha (sample species richness) and gamma (large area species richness) scales, whereas the break at about 2,000 m was clearly from beta (turnover) species richness. Only six species (12%) in the examined families were found in the deepest areas. The slope and deep-water polychaete fauna differs substantially from west Norwegian shelf and costal fauna. Not more than 30% of the species in the examined families were recorded in coastal and shelf waters, and several presumably refer to species complexes. The strong faunal change coincides with the upper border of cold sub-zero temperature deep water at the shelf break and upper slope. Polychaete taxonomy of the deep-water fauna is generally underdeveloped, illustrated by a high proportion of recently described or undescribed species (about 40%) in the examined families. Based on the present results, we hypothesise that the cold Nordic Sea deep-water polychaete fauna differs significantly from the North Atlantic deep fauna and rather is more similar to the fauna of deep Arctic waters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.