Demographic history and reproductive output correlates with intraspecific genetic variation in seven species of Indo-Pacific mangrove crabs

The spatial distribution and the amount of intraspecific genetic variation of marine organisms are strongly influenced by many biotic and abiotic factors. Comparing biological and genetic data characterizing species living in the same habitat can help to elucidate the processes driving these variation patterns. Here, we present a comparative multispecies population genetic study on seven mangrove crabs co-occurring in the West Indian Ocean characterized by planktotrophic larvae with similar pelagic larval duration. Our main aim was to investigate whether a suite of biological, behavioural and ecological traits could affect genetic diversities of the study species in combination with historical demographic parameters. As possible current explanatory factors, we used the intertidal micro-habitat colonised by adult populations, various parameters of individual and population fecundity, and the timing of larval release. As the genetic marker, we used partial sequences of cytochrome oxidase subunit I gene. Genetic and ecological data were collected by the authors and/or gathered from primary literature. Permutational multiple regression models and ANOVA tests showed that species density and their reproductive output in combination with historical demographic parameters could explain the intraspecific genetic variation indexes across the seven species. In particular, species producing consistently less eggs per spawning event showed higher values of haplotype diversity. Moreover, Tajima's D parameters well explained the recorded values for haplotype diversity and average γst. We concluded that current intraspecific gene diversities in crabs inhabiting mangrove forests were affected by population fecundity as well as past demographic history. The results were also discussed in terms of management and conservation of fauna in the Western Indian Ocean mangroves

Coordinated RNA-Seq and peptidomics identify neuropeptides and G-protein coupled receptors (GPCRs) in the large pine weevil Hylobius abietis, a major forestry pest

Hylobius abietis (Linnaeus), or large pine weevil (Coleoptera, Curculionidae), is a pest of European coniferous forests. In order to gain understanding of the functional physiology of this species, we have assembled a de novo transcriptome of H. abietis, from sequence data obtained by Next Generation Sequencing. In particular, we have identified genes encoding neuropeptides, peptide hormones and their putative G-protein coupled receptors (GPCRs) to gain insights into neuropeptide-modulated processes. The transcriptome was assembled de novo from pooled paired-end, sequence reads obtained from RNA from whole adults, gut and central nervous system tissue samples. Data analysis was performed on the transcripts obtained from the assembly including, annotation, gene ontology and functional assignment as well as transcriptome completeness assessment and KEGG pathway analysis. Pipelines were created using Bioinformatics tools and techniques for prediction and identification of neuropeptides and neuropeptide receptors. Peptidomic analysis was also carried out using a combination of MALDI-TOF as well as Q-Exactive Orbitrap mass spectrometry to confirm the identified neuropeptide. 41 putative neuropeptide families were identified in H. abietis, including Adipokinetic hormone (AKH), CAPA and DH31. Neuropeptide F, which has not been yet identified in the model beetle T. castaneum, was identified. Additionally, 24 putative neuropeptide and 9 leucine-rich repeat containing G protein coupled receptor-encoding transcripts were determined using both alignment as well as non-alignment methods. This information, submitted to the NCBI sequence read archive repository (SRA accession: SRP133355), can now be used to inform understanding of neuropeptide-modulated physiology and behaviour in H. abietis; and to develop specific neuropeptide-based tools for H. abietis control

The neuropeptidome of Carabus (Coleoptera, Adephaga: Carabidae)

Neuropeptides are signaling molecules involved in the regulation of virtually all physiological functions of Metazoa. In insects, more than 50 neuropeptide genes can be present in a single species, and thus neuropeptidergic systems are attractive targets for the development of environmentally friendly pesticides. Such approaches require not only knowledge of the neuropeptidomes of pests, but also detailed knowledge of the corresponding systems in beneficial insects. In Coleoptera, there is no profound knowledge of the neuropeptides in the adephagan lineage, which contains many of the ecologically important predators of caterpillars. We analyzed by transcriptomics, mass spectrometry and immunohistochemistry the neuropeptidomes of the two Carabus species C. violaceus and C. problematicus. This information, which contains detailed data on the differential processing of CAPA peptides, allows for the recognition of features typical only of the polyphagan lineage with its many pests. The neuropeptidomics data, which also confirmed the processing of a number of protein hormones, represent the highest number of neuropeptides that have been identified so far from Coleoptera. The sequences of the mature neuropeptides of the two Carabus species, whose ancestors separated about 13 Mya, are highly similar and no sequence substitutions were found in single-copy neuropeptides

Population genetics, gene flow, and biogeographical boundaries of Carcinus aestuarii (Crustacea: Brachyura: Carcinidae) along the European Mediterranean coast

Carcinus aestuarii Nardo, 1847 is a widespread coastal crab species throughout the Mediterranean Sea with a pelagic larval phase. This species tolerates a wide range of environmental conditions and typically inhabits fragmented habitats, such as embayments, lagoons and estuaries. It is therefore a good candidate species for studying and testing different phylogeographical hypotheses in the Mediterranean Sea. By contrast to its Atlantic sister species, Carcinus maenas, studies on the population genetic structure of C. aestuarii in its native range are still scarce. In the present study, specimens from along the European Mediterranean Sea were collected and DNA-sequenced and analyses were applied to discriminate between present day and historical factors influencing the population genetic structure of this species. The results obtained demonstrate the existence of two genetically distinct geographical groups, corresponding to the eastern and western Mediterranean, with further subdivision within the East Mediterranean Basin. A strong asymmetric gene flow was recorded toward the Eastern Basin, which may play a crucial role in shaping the present day biogeographical patterns of this species and potentially other sympatric ones with pelagic larvae.We are indebted to Sara Fratini, Carsten Müller, Yvan Perez, Pere Abelló, Florian Gmeiner, Silke Reuschel, Ruth Jesse, Sebastian Klaus, and Henrik M. Schubart, as well as several students of the University of Regensburg for their help in collecting and sequencing specimens of C. aestuarii. We thank three anonymous reviewers for their helpful comments. Travel for this study was partly financed through DAAD exchange programmes to Italy (VIGONI D/04/ 47157 thanks to Marco Vannini) and Spain (Acciones Integradas Hispano-Alemanas D/03/40344 thanks to JoséA. Cuesta). The authors declare that there are no conflicts of interest.publishe

Temporal patterns of megalopal settlement in different areas of an East African mangrove forest (Gazi Bay, Kenya)

© 2015, Springer International Publishing Switzerland. Most intertidal brachyurans produce planktonic larvae which develop pelagically and, after a certain time in the ocean, migrate towards the habitats that they will eventually settle in. One of the main physical processes affecting larval release and settlement in species inhabiting estuaries and mangroves is the tidal regime. In this study, we investigated whether patterns of settlement of brachyuran larvae at four sites (differing in tidal inundation and crab zonation) of a Kenyan mangrove were affected by the diurnal and lunar cycle of the tide. We collected megalopae at the four sites twice a day throughout two lunar months. Settlement differed at the four sites: at the subtidal site (the main creek within the forest) megalopae arrived during diurnal and nocturnal neap and spring tides, while at the three sites within the forest settlement occurred only at spring tide periods. Specific differences among these latter sites existed in terms of full versus new moon spring tides and, to a smaller extent, with diurnal period. Our results show that larval settlement in mangrove forests takes place at both landward and seaward belts and is a temporally complex event, driven by tidal cycles, but also in synergy with other factors.Link_to_subscribed_fulltex

Stock structure and demographic history of the Indo-West Pacific mud crab Scylla serrata

The increasing exploitation of mangrove forests, without any sustainable planning, has been seriously compromising the survival of this ecosystem and of its exclusive resources. Scylla serrata is one of the most commercially exploited crabs inhabiting mangroves and estuaries of the Indo-Pacific region. This species is extensively harvested, mainly for selling to the tourist market, and, as a consequence, its populations are in constant decline. The aim of the present study was to assess the level of genetic exchange of S. serrata within the Western Indian Ocean (WIO), using a population genetic structure approach. To achieve this goal, we reconstructed the intra-specific geographic pattern of genetic variation by partial sequencing the mitochondrial DNA cytochrome oxidase subunit I, in samples from seven mangrove sites of the WIO. Our data set then encompassed all the sequences for the same genetic marker deposited in Genbank and corresponding to samples from South East Asia, Australia and some Pacific Islands: this allowed us to estimate the level of connectivity among S. serrata populations within its distribution area. Our results show that an unique Scylla serrata metapopulation exists within the WIO; while throughout the entire Indo-Pacific region at least three distinct genetic stocks occur, corresponding to well-defined geographic regions (WIO, Eastern Australia and Pacific Ocean, North-Western Australia). South East China appears as the depositary of the most ancient haplotype and at the present time shares a haplotype with the Red Sea. The WIO populations show the signature of recent population bottlenecks, as expected for populations deeply exploited in a recent past. On the basis of our results, we can conclude that both the S. serrata populations and their habitats, i.e. mangrove forests and estuaries, of the WIO require future management and conservation regulations to avoiding overexploitation of this important key predator and marketable resource. © 2009 Elsevier Ltd. All rights reserved.Link_to_subscribed_fulltex