Illegal, unreported and unregulated fishing has had a major role in the overexploitation of global fish populations. In response, international regulations have been imposed and many fisheries have been 'eco-certified' by consumer organizations, but methods for independent control of catch certificates and eco-labels are urgently needed. Here we show that, by using geneassociated single nucleotide polymorphisms, individual marine fish can be assigned back to population of origin with unprecedented high levels of precision. By applying high differentiation single nucleotide polymorphism assays, in four commercial marine fish, on a pan-European scale, we find 93-100% of individuals could be correctly assigned to origin in policy-driven case studies. We show how case-targeted single nucleotide polymorphism assays can be created and forensically validated, using a centrally maintained and publicly available database. our results demonstrate how application of gene-associated markers will likely revolutionize origin assignment and become highly valuable tools for fighting illegal fishing and mislabelling worldwide.

Shallow population structure is generally reported for most marine fish and explained as a consequence of high dispersal, connectivity and large population size. Targeted gene analyses and more recently genome-wide studies have challenged such view, suggesting that adaptive divergence might occur even when neutral markers provide genetic homogeneity across populations. Here, 381 SNPs located in transcribed regions were used to assess large- and fine-scale population structure in the European hake (Merluccius merluccius), a widely distributed demersal species of high priority for the European fishery. Analysis of 850 individuals from 19 locations across the entire distribution range showed evidence for several outlier loci, with significantly higher resolving power. While 299 putatively neutral SNPs confirmed the genetic break between basins (F(CT) = 0.016) and weak differentiation within basins, outlier loci revealed a dramatic divergence between Atlantic and Mediterranean populations (F(CT) range 0.275-0.705) and fine-scale significant population structure. Outlier loci separated North Sea and Northern Portugal populations from all other Atlantic samples and revealed a strong differentiation among Western, Central and Eastern Mediterranean geographical samples. Significant correlation of allele frequencies at outlier loci with seawater surface temperature and salinity supported the hypothesis that populations might be adapted to local conditions. Such evidence highlights the importance of integrating information from neutral and adaptive evolutionary patterns towards a better assessment of genetic diversity. Accordingly, the generated outlier SNP data could be used for tackling illegal practices in hake fishing and commercialization as well as to develop explicit spatial models for defining management units and stock boundaries.

BackgroundThe insect order Neuroptera encompasses more than 5,700 described species. To date, only three neuropteran mitochondrial genomes have been fully and one partly sequenced. Current knowledge on neuropteran mitochondrial genomes is limited, and new data are strongly required. In the present work, the mitochondrial genome of the ascalaphid owlfly Libelloides macaronius is described and compared with the known neuropterid mitochondrial genomes: Megaloptera, Neuroptera and Raphidioptera. These analyses are further extended to other endopterygotan orders.ResultsThe mitochondrial genome of L. macaronius is a circular molecule 15,890 bp long. It includes the entire set of 37 genes usually present in animal mitochondrial genomes. The gene order of this newly sequenced genome is unique among Neuroptera and differs from the ancestral type of insects in the translocation of trnC. The L. macaronius genome shows the lowest A+T content (74.50%) among known neuropterid genomes. Protein-coding genes possess the typical mitochondrial start codons, except for cox1, which has an unusual ACG. Comparisons among endopterygotan mitochondrial genomes showed that A+T content and AT/GC-skews exhibit a broad range of variation among 84 analyzed taxa. Comparative analyses showed that neuropterid mitochondrial protein-coding genes experienced complex evolutionary histories, involving features ranging from codon usage to rate of substitution, that make them potential markers for population genetics/phylogenetics studies at different taxonomic ranks. The 22 tRNAs show variable substitution patterns in Neuropterida, with higher sequence conservation in genes located on the α strand. Inferred secondary structures for neuropterid rrnS and rrnL genes largely agree with those known for other insects. For the first time, a model is provided for domain I of an insect rrnL. The control region in Neuropterida, as in other insects, is fast-evolving genomic region, characterized by AT-rich motifs.ConclusionsThe new genome shares many features with known neuropteran genomes but differs in its low A+T content. Comparative analysis of neuropterid mitochondrial genes showed that they experienced distinct evolutionary patterns. Both tRNA families and ribosomal RNAs show composite substitution pathways. The neuropterid mitochondrial genome is characterized by a complex evolutionary history.

The gilthead sea bream (Sparus aurata L.) is a marine fish of great importance for fisheries and aquaculture. It has also a peculiar sex-determination system, being a protandrous hermaphrodite. Here we report the construction of a first-generation genetic linkage map for S. aurata, based on 204 microsatellite markers. Twenty-six linkage groups (LG) were found. The total map length was 1241.9 cM. The ratio between sex-specific map lengths was 1:1.2 (male:female). Comparison with a preliminary radiation hybrid (RH) map reveals a good concordance, as all markers located in a single LG are located in a single RH group, except for Ad-25 and CId-31. Comparison with the Tetraodon nigroviridis genome revealed a considerable number of evolutionary conserved regions (ECRs) between the two species. The mean size of ECRs was 182 bp (sequence identity 60-90%). Forty-one ECRs have a known chromosomal location in the pufferfish genome. Despite the limited number of anchoring points, significant syntenic relationships were found. The linkage map presented here provides a robust comparative framework for QTL analysis in S. aurata and is a step toward the identification of genetic loci involved both in the determination of economically important traits and in the individual timing of sex reversal. T HE gilthead sea bream (Sparus aurata L.) is a marine teleost fish that belongs to the family Sparidae. This family contains .100 species, which are divided into two large clades (groups A and B) according to the most recent molecular data (Orrell and Carpenter 2004). Sparids (porgies or sea breams) are demersal fish commonly found in temperate and tropical waters, with a maximum of diversity in the northeast Atlantic and the Mediterranean region (Bauchot and Hureau 1986), and they represent a key element of the coastal marine ecosystem. Sparids are also of great importance for fisheries and aquaculture, being excellent food fish, with high commercial value. S. aurata is the most prominent, with an average cultured production of 100 million metric tons per year. The great importance of the gilthead sea bream for marine aquaculture has fueled an increasing number of studies in many different areas such as immunology, endocrinology, bone morphology, and muscle physiology. Moreover, the genomic tool kit for S. aurata has been constantly improving, as a firstgeneration cDNA microarray was recently reported (Sarropoulou et al. 2005), a preliminary radiation hybrid (RH) map has been constructed (Senger et al. 2006), and a medium-scale expressed sequence tag (EST) sequencing project has been recently completed (A. Canario, personal communication). An improved RH map with .1000 markers (G. Kotoulas, personal communication) and an oligo array representing .10,000 unique transcripts (L. Bargelloni, personal communication) are expected by the end of 2006. Therefore, the genome of the gilthead sea bream is rapidly becoming one of the best characterized among teleost species, apart from classical models such as Brachydanio rerio (zebrafish...

Insect mitochondrial genomes (mtDNA) are usually double helical and circular molecules containing 37 genes that are encoded on both strands. The arrangement of the genes is not constant for all species, and produces distinct gene orders (GOs) that have proven to be diagnostic in defining clades at different taxonomic levels. In general, it is believed that distinct taxa have a very low chance of sharing identically arranged GOs. However, examples of identical, homoplastic local rearrangements occurring in distinct taxa do exist. In this study, we sequenced the complete mtDNAs of the ants Formica fusca and Myrmica scabrinodis (Formicidae, Hymenoptera) and compared their GOs with those of other Insecta. The GO of F. fusca was found to be identical to the GO of Dytrisia (the largest clade of Lepidoptera). This finding is the first documented case of an identical GO shared by distinct groups of Insecta, and it is the oldest known event of GO convergent evolution in animals. Both Hymenoptera and Lepidoptera acquired this GO early in their evolution. Using a phylogenetic approach combined with new bioinformatic tools, the chronological order of the evolutionary events that produced the diversity of the hymenopteran GOs was determined. Additionally, new local homoplastic rearrangements shared by distinct groups of insects were identified. Our study showed that local and global homoplasies affecting the insect GOs are more widespread than previously thought. Homoplastic GOs can still be useful for characterizing the various clades, provided that they are appropriately considered in a phylogenetic and taxonomic context.