Next-generation sequencing and the collection of genome-wide data allow identifying adaptive variation and footprints of directional selection. Using a large SNP data set from 259 RAD-sequenced European eel individuals (glass eels) from eight locations between 34 and 64(o) N, we examined the patterns of genome-wide genetic diversity across locations. We tested for local selection by searching for increased population differentiation using F(ST) -based outlier tests and by testing for significant associations between allele frequencies and environmental variables. The overall low genetic differentiation found (F(ST) = 0.0007) indicates that most of the genome is homogenized by gene flow, providing further evidence for genomic panmixia in the European eel. The lack of genetic substructuring was consistent at both nuclear and mitochondrial SNPs. Using an extensive number of diagnostic SNPs, results showed a low occurrence of hybrids between European and American eel, mainly limited to Iceland (5.9%), although individuals with signatures of introgression several generations back in time were found in mainland Europe. Despite panmixia, a small set of SNPs showed high genetic differentiation consistent with single-generation signatures of spatially varying selection acting on glass eels. After screening 50 354 SNPs, a total of 754 potentially locally selected SNPs were identified. Candidate genes for local selection constituted a wide array of functions, including calcium signalling, neuroactive ligand-receptor interaction and circadian rhythm. Remarkably, one of the candidate genes identified is PERIOD, possibly related to differences in local photoperiod associated with the >30° difference in latitude between locations. Genes under selection were spread across the genome, and there were no large regions of increased differentiation as expected when selection occurs within just a single generation due to panmixia. This supports the conclusion that most of the genome is homogenized by gene flow that removes any effects of diversifying selection from each new generation.

Within the genus Phragmites (Poaceae), the species P. australis (the common reed) is virtually cosmopolitan, and shows considerable variation in ploidy level and morphology. Genetic variation in Phragmites was studied using AFLPs, and analysed with parsimony and distance methods. Groups of P. australis strongly supported in the analyses include one that comprises all South American clones, a distinct group from the US Gulf Coast, and a group of E. Asian and Australian octoploids. Among the other species, the paleotropical P. vallatoria is supported as monophyletic and most closely related to the paraphyletic P. mauritianus and to the Gulf Coast and S. American groups. The E. Asian species P. japonicus is closely related to a group of P. australis clones mostly from central North America. Tetraploidy predominates in the genus, and optimisation of chromosome numbers onto the phylogeny shows that higher ploidy levels have evolved many times.

Little is known about local adaptations in marine fishes since population genetic surveys in these species have typically not applied genetic markers subject to selection. In this study, we used a candidate gene approach to investigate adaptive population divergence in the European flounder (Platichthys flesus L.) throughout the northeastern Atlantic. We contrasted patterns of genetic variation in a presumably neutral microsatellite baseline to patterns from a heat-shock cognate protein gene, Hsc70. Using two different neutrality tests we found that the microsatellite data set most likely represented a neutral baseline. In contrast, Hsc70 strongly deviated from neutral expectations. Importantly, when estimating standardized levels of population divergence (F ST 0 ), we also found a large discrepancy in the patterns of structuring in the two data sets. Thus, samples grouped according to geographical or historical proximity with regards to microsatellites, but according to environmental similarities with regards to Hsc70. The differences between the data sets were particularly pronounced in pairwise comparisons involving populations in the western and central Baltic Sea. For instance, the genetic differentiation between geographically close Baltic Sea and North Sea populations was found to be 0.02 and 0.45 for microsatellites and Hsc70 respectively. Our results strongly suggest adaptive population divergence and indicate local adaptations at the DNA level in a background of high levels of gene flow, typically found in many marine fish species. Furthermore, this study highlights the usefulness of the candidate gene approach for demonstrating local selection in non-model organisms such as most marine fishes.

A novel isoform of human elongation factor‐1α (EF‐1α2) has been characterised. It shows a high similarity to other EF‐1α proteins, especially to a rat EF‐1α variant and it has all the characteristics of a functional EF‐1α protein. The pattern of expression of both EF‐1α2 and EF‐1α was analysed in different human tissues. This showed that the two proteins were differentially expressed, EF‐1α2 was expressed in brain, heart, skeletal muscle and in the transformed cell lines AMA and K14, but was undetectable in other tissues and in both primary and transformed human fibroblasts. EF‐1α was expressed in brain, placenta, lung, liver, kidney, pancreas and in all the cell lines that we have analysed but barely detectable in heart and skeletal muscle.

Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours -- the 'arribada' population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%- the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty-nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.

A preliminary epidemiological survey indicated an association between Ascaris infections in Danish patients and contact with pigs or pig manure. In the present study, we compared Ascaris worms collected from humans and Ascaris worms collected from pigs by amplified fragment length polymorphism (AFLP) analysis, a technique for whole-genome fingerprinting, and by PCR-linked restricted fragment length polymorphism (PCR-RFLP) analysis of the internal transcribed spacer region of nuclear rDNA. The AFLP data were analyzed by distance-and model-based clustering methods. These results assigned Ascaris worms from Danish patients to a cluster different from that for worms from humans in other geographic areas. In contrast, worms from humans and pigs in Denmark were assigned to the same cluster. These results were supported by the PCR-RFLP results. Thus, all of the examined Danish patients had acquired Ascaris infections from domestic pigs; ascariasis may therefore be considered a zoonotic disease in Denmark.

Heat shock genes are considered to be likely candidate genes for environmental stress resistance. Nucleotide variation in the coding sequence of the small heat shock genes (hsps) hsp26 and hsp27 from Drosophila melanogaster was studied in flies originating from the Netherlands and eastern Australia. The hsp26 gene was polymorphic for an insertion/deletion of three extra amino acids and two nonsynonymous changes in all populations. The hsp27 gene exhibited two nonsynonymous changes and three synonymous mutations. The hsp26 polymorphism showed a latitudinal cline along the east coast of Australia. This pattern was not confounded by the fact that the shsps are located in the inversion In(3 L)P which also shows a latitudinal cline in eastern Australia. A similar latitudinal cline was found for the previously described variation in hsp23, while frequencies of hsp27 alleles did not change with latitude. These findings suggest that variation at two of the shsps or closely linked loci are under selection in natural populations of D. melanogaster.

Reduced representation genome sequencing such as RAD (Restriction-site Associated 2 DNA) sequencing is finding increased use to identify and genotype large numbers of 3 single nucleotide polymorphisms (SNPs) in model and non-model species. We 4 generated a unique resource of novel SNP markers for the European eel using the 5 RAD sequencing approach that were simultaneously identified and scored in a 6 genome-wide scan of 30 individuals. Whereas genomic resources are increasingly 7 becoming available for this species, including the recent release of a draft genome, no 8 genome-wide set of SNP markers was available until now. The generated SNPs were 9 widely distributed across the eel genome, aligning to 4,779 different contigs and 10 19,703 different scaffolds. Significant variation was identified, with an average 11 nucleotide diversity of 0.00529 across individuals. Results varied widely across the 12 genome, ranging from 0.00048 to 0.00737 per locus. Based on the average nucleotide 13 diversity across all loci, long-term effective population size was estimated to range 14 between 132,000 and 1,320,000, which is much higher than previous estimates based 15 on microsatellite loci. The generated SNP resource consisting of 82,425 loci and 16 376,918 associated SNPs provides a valuable tool for future population genetics and 17 genomics studies and allows for targeting specific genes and particularly interesting 18 regions of the eel genome.