Population Structure and Dispersal Patterns within and between Atlantic and Mediterranean Populations of a Large-Range Pelagic Seabird

Dispersal is critically linked to the demographic and evolutionary trajectories of populations, but in most seabird species it may be difficult to estimate. Using molecular tools, we explored population structure and the spatial dispersal pattern of a highly pelagic but philopatric seabird, the Cory's shearwater Calonectris diomedea. Microsatellite fragments were analysed from samples collected across almost the entire breeding range of the species. To help disentangle the taxonomic status of the two subspecies described, the Atlantic form C. d. borealis and the Mediterranean form C. d. diomedea, we analysed genetic divergence between subspecies and quantified both historical and recent migration rates between the Mediterranean and Atlantic basins. We also searched for evidence of isolation by distance (IBD) and addressed spatial patterns of gene flow. We found a low genetic structure in the Mediterranean basin. Conversely, strong genetic differentiation appeared in the Atlantic basin. Even if the species was mostly philopatric (97%), results suggest recent dispersal between basins, especially from the Atlantic to the Mediterranean (aprox. 10% of migrants/generation across the last two generations). Long-term gene flow analyses also suggested an historical exchange between basins (about 70 breeders/generation). Spatial analysis of genetic variation indicates that distance is not the main factor in shaping genetic structure in this species. Given our results we recommend gathering more data before concluded whether these taxa should be treated as two species or subspecies. © 2013 Genovart et al.Peer Reviewe

Islands beneath islands: phylogeography of a groundwater amphipod crustacean in the Balearic archipelago

<p>Abstract</p> <p>Background</p> <p>Metacrangonyctidae (Amphipoda, Crustacea) is an enigmatic continental subterranean water family of marine origin (thalassoid). One of the species in the genus, <it>Metacrangonyx longipes</it>, is endemic to the Balearic islands of Mallorca and Menorca (W Mediterranean). It has been suggested that the origin and distribution of thalassoid crustaceans could be explained by one of two alternative hypotheses: (1) active colonization of inland freshwater aquifers by a marine ancestor, followed by an adaptative shift; or (2) passive colonization by stranding of ancestral marine populations in coastal aquifers during marine regressions. A comparison of phylogenies, phylogeographic patterns and age estimations of clades should discriminate in favour of one of these two proposals.</p> <p>Results</p> <p>Phylogenetic relationships within <it>M. longipes </it>based on three mitochondrial DNA (mtDNA) and one nuclear marker revealed five genetically divergent and geographically structured clades. Analyses of cytochrome oxidase subunit 1 (<it>cox1</it>) mtDNA data showed the occurrence of a high geographic population subdivision in both islands, with current gene flow occurring exclusively between sites located in close proximity. Molecular-clock estimations dated the origin of <it>M. longipes </it>previous to about 6 Ma, whereas major cladogenetic events within the species took place between 4.2 and 2.0 Ma.</p> <p>Conclusions</p> <p><it>M. longipes </it>displayed a surprisingly old and highly fragmented population structure, with major episodes of cladogenesis within the species roughly correlating with some of the major marine transgression-regression episodes that affected the region during the last 6 Ma. Eustatic changes (vicariant events) -not active range expansion of marine littoral ancestors colonizing desalinated habitats-explain the phylogeographic pattern observed in <it>M. longipes</it>.</p

Genomic Resources for Sea Lice: Analysis of ESTs and Mitochondrial Genomes

Sea lice are common parasites of both farmed and wild salmon. Salmon farming constitutes an important economic market in North America, South America, and Northern Europe. Infections with sea lice can result in significant production losses. A compilation of genomic information on different genera of sea lice is an important resource for understanding their biology as well as for the study of population genetics and control strategies. We report on over 150,000 expressed sequence tags (ESTs) from five different species (Pacific Lepeophtheirus salmonis (49,672 new ESTs in addition to 14,994 previously reported ESTs), Atlantic L. salmonis (57,349 ESTs), Caligus clemensi (14,821 ESTs), Caligus rogercresseyi (32,135 ESTs), and Lernaeocera branchialis (16,441 ESTs)). For each species, ESTs were assembled into complete or partial genes and annotated by comparisons to known proteins in public databases. In addition, whole mitochondrial (mt) genome sequences of C. clemensi (13,440 bp) and C. rogercresseyi (13,468 bp) were determined and compared to L. salmonis. Both nuclear and mtDNA genes show very high levels of sequence divergence between these ectoparastic copepods suggesting that the different species of sea lice have been in existence for 37–113 million years and that parasitic association with salmonids is also quite ancient. Our ESTs and mtDNA data provide a novel resource for the study of sea louse biology, population genetics, and control strategies. This genomic information provides the material basis for the development of a 38K sea louse microarray that can be used in conjunction with our existing 44K salmon microarray to study host–parasite interactions at the molecular level. This report represents the largest genomic resource for any copepod species to date

La pèrdua de progressió en l’actual sistema tributari

[cat] El treball tracta els imposts directes progressius més importants, en primer lloc analitza l’impost de la Renda de les Persones Físiques, que és un dels principals eixos del sistema tributari espanyol. En segon lloc l’impost sobre Successions i Donacions, que a nivell de recaptació no és massa important, però que té una funció redistributiva de la riquesa. En tercer lloc, l’impost sobre Patrimoni, que té una funció censal de les propietats que té cada persona física, i que actualment està en el punt de mira per part del Govern i experts per veure si s’elimina de forma definitiva. Finalment, l’impost sobre la Renda de No Residents que en quant a recaptació no és significatiu. En tots s’analitzarà la normativa que els afecta, tant estatal com autonòmica, l’evolució que ha seguit la recaptació en cada cas i les principals modificacions que s’hi han dut a terme. La finalitat del treball és analitzar les variacions que hi ha hagut al llarg dels darrers vint anys en la progressió d’aquests imposts. A més, es tractarà l’actualitat pel que fa als imposts, ja que han sofert modificacions degut a la crisi financera de l’any 2008 i de cara al 2015 s’estan debatent nombroses alternatives a aplicar, en el marc de reduir la imposició directa i augmentar la indirecta

Genetic diversity and geographic patterns of the amphipod genus Metacrangonyx (crustacea; gammaridea)

[cat] Els metacrangoníctids són una família d’amfípodes estigobionts els quals presenten una distribució global extremadament disjunta. Una única espècie endèmica balear, M. longipes, es troba àmpliament distribuïda arreu de les Balears. Aquesta família compta amb 18 espècies descrites repartides arreu de Nord d’Àfrica, Elba (Itàlia), Balears, Fuerteventura, Orient Mitjà, i a la illa de La Hispaniola. Atès que aquesta família presenta una limitada capacitat dispersiva i presenta una distribució amfi-atlàntica, el seu patró biogeogràfic s’ha associat esdeveniments vicariants per tectònica de plaques i a models d’especiació peripàtrica. He examinat els patrons de diversificació i colonització dels hàbitats subterranis, tant a nivell micro- com macroevolutiu. Els resultats obtinguts suggereixen que moviments eustàtics, semblen ésser els moduladors de les relacions evolutives de M. longipes. Aquest patró de vicariança també s’ha observat a la resta de la família: l’obertura del Nord-Atlàntic per deriva continental explicaria els actuals patrons de diversificació i distribució d’aquesta família

The complete mitochondrial genome of the subterranean crustacean Metacrangonyx longipes (Amphipoda): A unique gene order and extremely short control region

Metazoan mitochondrial genomes usually consist of the same gene set, but some taxonomic groups show a considerable variety in gene order and nucleotide composition. The mitochondrial genomes of 37 crustaceans are currently known. Within the malacostracan superorder Peracarida, only three partial mitogenome sequences and the complete sequence of Ligia oceanica (Isopoda) are available. Frequent translocation events have changed the mitochondrial gene order in crustaceans, providing an opportunity to study the patterns and mechanisms of mitogenome rearrangement and to determine their impact on phylogenetic reconstructions. Here we report the first complete nucleotide sequence of an amphipod species, Metacrangonyx longipes, belonging to a phylogenetically enigmatic family occurring in continental subterranean waters. The genome has 14,113 bp and contains the usual 13 protein coding genes and two rRNA subunits, but only 21 out of the typical 22 tRNA genes of Metazoa. This is the shortest mitogenome described thus far for a crustacean and also one of the richest in AT (76.03%). The genome compactness results from a very small control region of 76 bp, the occurrence of frequent gene overlap, and the absence of large non-coding fragments. Six of the protein-coding genes have unusual start codons. Comparison of individual protein coding genes with the sequences known for other crustaceans suggests that nad2, nad6, nad4L and atp8 show the highest divergence rates. M. longipes shows a unique crustacean mitogenome gene order, differing even from the condition found in Parhyale hawaiiensis (Amphipoda), whose coding sequence has also been completed in the present study. © 2009 Informa UK Ltd.Peer Reviewe

Next-generation sequencing, phylogenetic signal and comparative mitogenomic analyses in Metacrangonyctidae (Amphipoda: Crustacea)

Abstract. Background: Comparative mitochondrial genomic analyses are rare among crustaceans below the family or genus level. The obliged subterranean crustacean amphipods of the family Metacrangonyctidae, found from the Hispaniola (Antilles) to the Middle East, including the Canary Islands and the peri-Mediterranean region, have an evolutionary history and peculiar biogeography that can respond to Tethyan vicariance. Indeed, recent phylogenetic analysis using all protein-coding mitochondrial sequences and one nuclear ribosomal gene have lent support to this hypothesis (Bauzà-Ribot et al. 2012). Results: We present the analyses of mitochondrial genome sequences of 21 metacrangonyctids in the genera Metacrangonyx and Longipodacrangonyx, covering the entire geographical range of the family. Most mitogenomes were attained by next-generation sequencing techniques using long-PCR fragments sequenced by Roche FLX/454 or GS Junior pyro-sequencing, obtaining a coverage depth per nucleotide of up to 281×. All mitogenomes were AT-rich and included the usual 37 genes of the metazoan mitochondrial genome, but showed a unique derived gene order not matched in any other amphipod mitogenome. We compare and discuss features such as strand bias, phylogenetic informativeness, non-synonymous/synonymous substitution rates and other mitogenomic characteristics, including ribosomal and transfer RNAs annotation and structure. Conclusions: Next-generation sequencing of pooled long-PCR amplicons can help to rapidly generate mitogenomic information of a high number of related species to be used in phylogenetic and genomic evolutionary studies. The mitogenomes of the Metacrangonyctidae have the usual characteristics of the metazoan mitogenomes (circular molecules of 15,000-16,000 bp, coding for 13 protein genes, 22 tRNAs and two ribosomal genes) and show a conserved gene order with several rearrangements with respect to the presumed Pancrustacean ground pattern. Strand nucleotide bias appears to be reversed with respect to the condition displayed in the majority of crustacean mitogenomes since metacrangonyctids show a GC-skew at the (+) and (−) strands; this feature has been reported also in the few mitogenomes of Isopoda (Peracarida) known thus far. The features of the rRNAs, tRNAs and sequence motifs of the control region of the Metacrangonyctidae are similar to those of the few crustaceans studied at presentThis work wsa supported by Spanish MCINN grants CGL2009-08256 and CGL2012-33597 partially financed with EU FEDER funds. MMBR was supported by a Spanish FPI fellowshipWe acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe

Mitogenomic phylogenetic analysis supports continental-scale vicariance in subterranean thalassoid crustaceans

Many continental subterranean water crustaceans (>stygobionts>) display extreme disjunct distributions, where different species in the same genus are isolated on continents or islands separated by broad oceanic expanses [1]. Despite their freshwater habitat, most of these taxa appear to be most closely related to typical marine groups (>thalassoid> origin) [2]. Among the hadzioids - thalassoid amphipods including the stygobiont families Hadziidae, Pseudoniphargidae, and Metacrangonyctidae - several genera are restricted to inland groundwaters ranging from the Caribbean region to the Mediterranean and Middle East, including interspersed oceanic islands [3]. This distribution might have arisen from Tethyan vicariance [4-7] triggered by the sequential occlusion of the former Tethys Sea, a vast circumtropical ocean existing from the Middle Jurassic up to 20 million years ago (mya). Previous studies have been based on morphological analyses or limited DNA sequence data, making it difficult to test this hypothesis [8-10]. We used complete mitochondrial protein-coding gene sequences, mainly obtained by next-generation sequencing methods and a nuclear ribosomal gene to resolve the phylogeny and to establish a time frame for diversification of the family Metacrangonyctidae (Amphipoda). The results were consistent with the plate tectonics vicariance hypothesis, with major diversifications occurring between 96 and 83 mya. © 2012 Elsevier Ltd.This work was supported by Spanish MCINN grant CGL2009-08256 and CSIC Intramural grant 200930I141, partially financed with EU FEDER funds. M.M.B.-R. benefited of a PhD Spanish FPI fellowship during the completion of this studyPeer Reviewe