Phylogeography of the <i>Rhabditis (Pellioditis) marina</i> species complex: evidence for cosmopolitanism, restricted gene flow, recent range expansions and accelerated evolution

The nematode Rhabditis (Pellioditis) marina has a worldwide distribution despite presumably low dispersal abilities. Recent studies on a local scale have illustrated that R. (P.) marina actually consists of several cryptic species which questions its true cosmopolitan distribution. We performed a phylogeographic study to identify micro- and macro-evolutionary processes shaping population structuring and speciation in the R. (P.) marina species complex. The mitochondrial COI gene was screened with the Single Strand Conformation Polymorphism method (SSCP) in 1292 specimens collected from decomposing macroalgae along the coasts of Western Europe, NE America, Mexico, South Africa and Australia. We found evidence for eleven cryptic species within R. (P.) marina that were sympatrically distributed. A strong genetic structuring was observed in all species and a genetic break was observed around the British Isles. A historical signature was present in species PmII showing evidence for two postglacial, northwards orientated expansions and for restricted gene flow with occasional long-distance dispersal. Our data also pointed to a contact zone in the Southern Bight of the North Sea. We found evidence for a true cosmopolitan distribution of nematode species due to occasional long-distance dispersal. In addition, an accelerated COI mutation rate was suggested for R. (P.) marina, which was about ten times higher than the generally applied molecular clock of 2 %. We further hypothesize that the cryptic radiation in R. (P.) marina is largely the result of allopatric speciation, and that the contemporary sympatric distribution results from occasional long-distance dispersal

Mitochondrial DNA variation and cryptic speciation within the free-living marine nematode <i>Pellioditis marina</i>

An inverse correlation between dispersal ability and genetic differentiation among populations of a species is frequently observed in the marine environment. We investigated the population genetic structure of the free-living marine nematode Pellioditis marina. A total of 426 bp of the mitochondrial cytochrome oxidase subunit 1 (COI) gene were surveyed on a geographical scale of approximately 100 km during spring 2003. Nematodes were collected from 2 coastal locations in Belgium, and from 2 estuaries and a saltwater lake (Lake Grevelingen) in The Netherlands. Molecular variation was assessed with the single-strand conformation polymorphism (SSCP) method. In total, 32 different haplotypes were observed, and sequence divergence among 452 individuals ranged from 0.2 to 10.6%. We discovered 4 distinct mitochondrial lineages, with low divergences within the lineages (0.2 to 1.6%) and high divergences between the lineages (5.1 to 10.6%). The nuclear ribosomal ITS (internal transcribed spacer) region showed concordant phylogenetic patterns, suggesting that nematode species diversity may be considerably underestimated. Analysis of molecular variance (AMOVA) indicated a strong genetic differentiation among populations. The Lake Grevelingen population was clearly differentiated from all other populations, but genetic structuring was also significant within the Westerschelde and was correlated with gradients in salinity and pollution. The observed population genetic structure is in accordance with the limited active dispersal capacity of P. marina, but is at variance with its significant potential for passive dispersal. We therefore suggest that autecological characteristics, including short generation time, high colonization potential and local adaptation, may be at the basis of this nematode’s population genetic structure

Genetic diversity study of broad range sponge taxa for new insights into the connectivity of cold-water coral reefs along the European margins

Deep-water coral banks and patches (most commonly built by Lophelia pertusa and Madrepora oculata), occur all along the European shelf margin, a few patches in the Mediterranean Sea and more extensive from Gibraltar up to Norway. They act as nurseries for fishes and harbor a multitude of invertebrates - some new to science and potential coral reefs endemics- making them Hotspots of Biodiversity. However, with the depletion of shallow-water fish stocks and the increasing commercial exploitation of the deep-sea environment, there is actually a high concern in Europe to better understand these ecosystems in order to achieve a sustainable management of these complex but fragile ecosystems. Sponges, which appear to dominate these aphotic ecosystems, were subjected to robust assessment of species distributional ranges. Preliminary comparison of datasets on bathyal (>200m) sponge biodiversity surveys highlighted several broadly ranged sponge species associated with different deepsea coral reef populations along the European margin. In particular, a limited series of generalized habitus (thin/hairy, thin/soft, hollow/bladder, massive/soft, megabenthic/siliceous) were reported. The five broad ranged taxa; Hexadella sp, Desmacella sp, Mycale sp, Plocamionida sp, Pheronema sp were selected as model species for these generalized habits, which may highlight a different role in the development and erosion of cold-water coral reef ecosystems. Studies of the molecular phylogeny and the intra-specific (genetic) diversity are being performed on these taxa with the purpose of detecting population structure and phylogeography. Such studies represent state-of-the-art, highly powerful tools for increasing insights into the connectivity of deep-sea reefs along the European margins. Data about the genetic structure of these species in several localities have a direct application for management; if gene exchange exists between populations then the loss of areas of reef will be less damaging to the overall genetic diversity of the species

Mysid crustaceans as standard models for the screening and testing of endocrine-disrupting chemicals

Author Posting. © Springer, 2007. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Ecotoxicology 16 (2007): 205-219, doi:10.1007/s10646-006-0122-0.Investigative efforts into the potential endocrine-disrupting effects of chemicals have mainly concentrated on vertebrates, with significantly less attention paid to understanding potential endocrine disruption in the invertebrates. Given that invertebrates account for at least 95% of all known animal species and are critical to ecosystem structure and function, it remains essential to close this gap in knowledge and research. The lack of progress regarding endocrine disruption in invertebrates is still largely due to: (1) our ignorance of mode-of-action, physiological control, and hormone structure and function in invertebrates; (2) lack of a standardized invertebrate assay; (3) the irrelevance to most invertebrates of the proposed activity-based biological indicators for endocrine disruptor exposure (androgen, estrogen and thyroid); (4) limited field studies. Past and ongoing research efforts using the standard invertebrate toxicity test model, the mysid shrimp, have aimed at addressing some of these issues. The present review serves as an update to a previous publication on the use of mysid shrimp for the evaluation of endocrine disruptors (Verslycke et al., 2004a). It summarizes recent investigative efforts that have significantly advanced our understanding of invertebrate-specific endocrine toxicity, population modeling, field studies, and transgeneration standard test development using the mysid model.Supported by a Fellowship of the Belgian American Educational Foundation

Early signaling, referral, and treatment of adolescent chronic pain: a study protocol

<p>Abstract</p> <p>Background</p> <p>Chronic pain is prevalent among young people and negatively influences their quality of life. Furthermore, chronic pain in adolescence may persist into adulthood. Therefore, it is important early on to promote the self-management skills of adolescents with chronic pain by improving signaling, referral, and treatment of these youngsters. In this study protocol we describe the designs of two complementary studies: a signaling study and an intervention study.</p> <p>Methods and design</p> <p>The signaling study evaluates the Pain Barometer, a self-assessed signaling instrument for chronic pain in adolescents. To evaluate the feasibility of the Pain Barometer, the experiences of youth-health care nurses will be evaluated in semi-structured interviews. Also, we will explore the frequencies of referral per health-care provider. The intervention study evaluates Move It Now, a guided self-help intervention via the Internet for teenagers with chronic pain. This intervention uses cognitive behavioural techniques, including relaxation exercises and positive thinking. The objective of the intervention is to improve the ability of adolescents to cope with pain. The efficacy of Move It Now will be examined in a randomized controlled trial, in which 60 adolescents will be randomly assigned to an experimental condition or a waiting list control condition.</p> <p>Discussion</p> <p>If the Pain Barometer is proven to be feasible and Move It Now appears to be efficacious, a health care pathway can be created to provide the best tailored treatment promptly to adolescents with chronic pain. Move It Now can be easily implemented throughout the Netherlands, as the intervention is Internet based.</p> <p>Trial registration</p> <p>Dutch Trial Register NTR1926</p

Contrasting patterns of population structure and gene flow facilitate exploration of connectivity in two widely distributed temperate octocorals

This is the final version of the article. Available from Springer Nature via the DOI in this record.Connectivity is an important component of metapopulation dynamics in marine systems and can influence population persistence, migration rates and conservation decisions associated with Marine Protected Areas (MPAs). In this study, we compared the genetic diversity, gene flow and population structure of two octocoral species, Eunicella verrucosa and Alcyonium digitatum, in the northeast Atlantic (ranging from the northwest of Ireland and the southern North Sea, to southern Portugal), using two panels of thirteen and eight microsatellite loci, respectively. Our results identified regional genetic structure in E. verrucosa partitioned between populations from southern Portugal, northwest Ireland, and Britain/France; subsequent hierarchical analysis of population structure also indicated reduced gene flow between southwest Britain and northwest France. However, over a similar geographical area, A. digitatum showed little evidence of population structure, suggesting high gene flow and/or a large effective population size; indeed, the only significant genetic differentiation detected in A. digitatum occurred between North Sea samples and those from the English Channel/northeast Atlantic. In both species the vast majority of gene flow originated from sample sites within regions, with populations in southwest Britain being the predominant source of contemporary exogenous genetic variants for the populations studied. Unsurprisingly, historical patterns of gene flow appeared more complex, though again southwest Britain appeared an important source of genetic variation for both species. Our findings have major conservation implications, particularly for E. verrucosa, a protected species in UK waters and listed by the IUCN as ‘Vulnerable’, and for the designation and management of European MPAs.We thank Natural England (project No. RP0286, contract No. SAE 03-02-146), the NERC (grant No. NE/L002434/1) and the University of Exeter for funding this research. Additional funding for sample collection, travel and microsatellite development was provided by the EU Framework 7 ASSEMBLE programme, agreement no. 227799, and NERC grant No. NBAF-362

Glacial History of the North Atlantic Marine Snail, Littorina saxatilis, Inferred from Distribution of Mitochondrial DNA Lineages

The North Atlantic intertidal gastropod, Littorina saxatilis (Olivi, 1792), exhibits extreme morphological variation between and within geographic regions and has become a model for studies of local adaptation; yet a comprehensive analysis of the species' phylogeography is lacking. Here, we examine phylogeographic patterns of the species' populations in the North Atlantic and one remote Mediterranean population using sequence variation in a fragment of the mitochondrial cytochrome b gene (607 bp). We found that, as opposed to many other rocky intertidal species, L. saxatilis has likely had a long and continuous history in the Northwest Atlantic, including survival during the last glacial maximum (LGM), possibly in two refugia. In the Northeast Atlantic, several areas likely harboured refugial populations that recolonized different parts of this region after glacial retreat, resulting in strong population structure. However, the outlying monomorphic Venetian population is likely a recent anthropogenic introduction from northern Europe and not a remnant of an earlier wider distribution in the Mediterranean Sea. Overall, our detailed phylogeography of L. saxatilis adds an important piece to the understanding of Pleistocene history in North Atlantic marine biota as well as being the first study to describe the species' evolutionary history in its natural range. The latter contribution is noteworthy because the snail has recently become an important model species for understanding evolutionary processes of speciation; thus our work provides integral information for such endeavours