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Data from: "Genome-wide microsatellite marker development from next-generation sequencing of two non-model bat species impacted by wind turbine mortality: Lasiurus borealis and L. cinereus (Vespertilionidae)" in Genomic Resources Notes accepted 1 October 2013 to 30 November 2013

Tree-roosting bats in the genus Lasiurus are widespread, migratory species that have not been well characterized for population genetic diversity and structure due to a lack of genetic resources. Generating genetic resources in Lasiurus is made pressing by the need for conservation genetic assessments of demographic trends in this genus, which comprise a large percentage of bat mortalities at wind turbine sites across North America. We report on marker development from whole-genome Illumina sequencing of the red bat (Lasirus borealis) and the hoary bat (L. cinereus). We generated paired-end libraries for a single individual of each species, sequenced on the Illumina HiSeq platform. We mapped a total of 46.6 million reads to the Myotis lucifigus reference genome, and used bioinformatics searches to identify tends of thousands of simple sequence repeats (SSRs) distributed across the bat genome. We selected 48 candidate microsatellite loci to develop cross-species primer sequences for Lasiurus, assembled these into multiplex combinations, and tested for amplification and polymorphism levels in a sample of 23 individuals from each of L. borealis and L. cinereus. In total, we identified 42 highly polymorphic loci that could be robustly amplified and scored, the majority of which (39) were also combinable into highly multiplexed assays of 4-8 loci each. The combination of new genomic sequence assemblies, a large set of highly polymorphic microsatellite loci, and the ability to efficiently multiplex represents a significant contribution to the genetic resources available for population and comparative genetic studies of bats.

opencc-zeroDec 2017View details →

Data from: Genetic patterns in Neotropical Magnolias (Magnoliaceae) using de novo developed microsatellite markers

Conserving tree populations safeguards forests since they represent key elements of the ecosystem. The genetic characteristics underlying the evolutionary success of the tree growth form: high genetic diversity, extensive gene flow and strong species integrity, contribute to their survival in terms of adaptability. However, different biological and landscape contexts challenge these characteristics. This study employs 63 de novo developed microsatellite or SSR (Single Sequence Repeat) markers in different datasets of nine Neotropical Magnolia species. The genetic patterns of these protogynous, insect-pollinated tree species occurring in fragmented, highly-disturbed landscapes were investigated. Datasets containing a total of 340 individuals were tested for their genetic structure and degree of inbreeding. Analyses for genetic structure depicted structuring between species, i.e. strong species integrity. Within the species, all but one population pair were considered moderate to highly differentiated, i.e. no indication of extensive gene flow between populations. No overall correlation was observed between genetic and geographic distance of the pairwise species' populations. In contrast to the pronounced genetic structure, there was no evidence of inbreeding within the populations, suggesting mechanisms favouring cross pollination and/or selection for more genetically diverse, heterozygous offspring. In conclusion, the data illustrate that the Neotropical Magnolias in the context of a fragmented landscape still have ample gene flow within populations, yet little gene flow between populations.

opencc-zeroDec 2014View details →

Data from: Genetic differentiation and phylogeography of partially sympatric species complex Rhizophora mucronata Lam. and R. stylosa Griff. using SSR markers

Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity management units and genetic structure. Here we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range by employing a suite of 20 informative nuclear SSR markers. Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait South China Sea and Northwest Pacific Ocean). In R. stylosa the genetic break was located more eastward between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow. Our findings have important implications on the conservation of mangroves especially relating to replanting efforts and the definition of ESUs in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species determine their respective genetic structure and avoid artificially promoting hybridization in mangrove restoration programmes.

Data from: Microsatellite markers from the Ion Torrent: a multi-species contrast to 454 shotgun sequencing

The development and screening of microsatellite markers have been accelerated by next-generation sequencing (NGS) technology and in particular GS-FLX pyro-sequencing (454). More recent platforms such as the PGM semiconductor sequencer (Ion Torrent) offer potential benefits such as dramatic reductions in cost, but to date have not been well utilized. Here, we critically compare the advantages and disadvantages of microsatellite development using PGM semiconductor sequencing and GS-FLX pyro-sequencing for two gymnosperm (a conifer and a cycad) and one angiosperm species. We show that these NGS platforms differ in the quantity of returned sequence data, unique microsatellite data and primer design opportunities, mostly consistent with the differences in read length. The strength of the PGM lies in the large amount of data generated at a comparatively lower cost and time. The strength of GS-FLX lies in the return of longer average length sequences and therefore greater flexibility in producing markers with variable product length, due to longer flanking regions, which is ideal for capillary multiplexing. These differences need to be considered when choosing a NGS method for microsatellite discovery. However, the ongoing improvement in read lengths of the NGS platforms will reduce the disadvantage of the current short read lengths, particularly for the PGM platform, allowing greater flexibility in primer design coupled with the power of a larger number of sequences.

Data from: Going where traditional markers have not gone before: utility of and promise for RAD-sequencing in marine invertebrate phylogeography and population genomics

Characterization of large numbers of single-nucleotide polymorphisms (SNPs) throughout a genome has the power to refine the understanding of population demographic history and to identify genomic regions under selection in natural populations. To this end, population genomic approaches that harness the power of next-generation sequencing to understand the ecology and evolution of marine invertebrates represent a boon to test long-standing questions in marine biology and conservation. We employed restriction-site-associated DNA sequencing (RAD-seq) to identify SNPs in natural populations of the sea anemone Nematostella vectensis, an emerging cnidarian model with a broad geographic range in estuarine habitats in North and South America, and portions of England. We identified hundreds of SNP-containing tags in thousands of RAD loci from 30 barcoded individuals inhabiting four locations from Nova Scotia to South Carolina. Population genomic analyses using high-confidence SNPs resulted in a highly-resolved phylogeography, a result not achieved in previous studies using traditional markers. Plots of locus-specific FST against heterozygosity suggest that a majority of polymorphic sites are neutral, with a smaller proportion suggesting evidence for balancing selection. Loci inferred to be under balancing selection were mapped to the genome, where 90% were located in gene bodies, indicating potential targets of selection. The results from analyses with and without a reference genome supported similar conclusions, further highlighting RAD-seq as a method that can be efficiently applied to species lacking existing genomic resources. We discuss the utility of RAD-seq approaches in burgeoning Nematostella research as well as in other cnidarian species, particularly corals and jellyfishes, to determine phylogeographic relationships of populations and identify regions of the genome undergoing selection.

opencc-zeroDec 2014View details →

Data from: MSAP markers and global cytosine methylation in plants: a literature survey and comparative analysis for a wild growing species

Methylation of DNA cytosines affects whether transposons are silenced and genes are expressed, and is a major epigenetic mechanism whereby plants respond to environmental change. Analyses of methylation-sensitive amplification polymorphism (MS-AFLP or MSAP) have been often used to assess methyl-cytosine changes in response to stress treatments and, more recently, in ecological studies of wild plant populations. MSAP technique does not require a sequenced reference genome and provides many anonymous loci randomly distributed over the genome for which the methylation status can be ascertained. Scoring of MSAP data, however, is not straightforward, and efforts are still required to standardize this step to make use of the potential to distinguish between methylation at different nucleotide contexts. Furthermore, it is not known how accurately MSAP infers genome-wide cytosine methylation levels in plants. Here, we analyse the relationship between MSAP results and the percentage of global cytosine methylation in genomic DNA obtained by HPLC analysis. A screening of literature revealed that methylation of cytosines at cleavage sites assayed by MSAP was greater than genome-wide estimates obtained by HPLC, and percentages of methylation at different nucleotide contexts varied within and across species. Concurrent HPLC and MSAP analyses of DNA from 200 individuals of the perennial herb Helleborus foetidus confirmed that methyl-cytosine was more frequent in CCGG contexts than in the genome as a whole. In this species, global methylation was unrelated to methylation at the inner CG site. We suggest that global HPLC and context-specific MSAP methylation estimates provide complementary information whose combination can improve our current understanding of methylation-based epigenetic processes in nonmodel plants.

Data from: Developing nuclear DNA phylogenetic markers in the angiosperm genus Leucadendron (Proteaceae): a next-generation sequencing transcriptomic approach

Despite the recent advances in generating molecular data, reconstructing species-level phylogenies for non-models groups remains a challenge. The use of a number of independent genes is required to resolve phylogenetic relationships, especially for groups displaying low polymorphism. In such cases, low-copy nuclear exons and non-coding regions, such as 3′ untranslated regions (3′-UTRs) or introns, constitute a potentially interesting source of nuclear DNA variation. Here, we present a methodology meant to identify new nuclear orthologous markers using both public-nucleotide databases and transcriptomic data generated for the group of interest by using next generation sequencing technology. To identify PCR primers for a non-model group, the genus Leucadendron (Proteaceae), we adopted a framework aimed at minimizing the probability of paralogy and maximizing polymorphism. We anchored when possible the right-hand primer into the 3′-UTR and the left-hand primer into the coding region. Seven new nuclear markers emerged from this search strategy, three of those included 3′-UTRs. We further compared the phylogenetic potential between our new markers and the ribosomal internal transcribed spacer region (ITS). The sequenced 3′-UTRs yielded higher polymorphism rates than the ITS region did. We did not find strong incongruences with the phylogenetic signal contained in the ITS region and the seven new designed markers but they strongly improved the phylogeny of the genus Leucadendron. Overall, this methodology is efficient in isolating orthologous loci and is valid for any non-model group given the availability of transcriptomic data.

opencc-zeroDec 2014View details →

Data from: Phylogeny and classification of the East Asian Amitostigma alliance (Orchidaceae: Orchideae) based on six DNA markers

Background: Tribe Orchideae dominates the orchid flora of the temperate Northern Hemisphere but its representatives in East Asia had been subject to less intensive phylogenetic study than those in Eurasia and North America. Although this situation was improved recently by the molecular phylogenetic study of Jin et al., comparatively few species were analyzed from the species-rich and taxonomically controversial East Asian Amitostigma alliance. Here, we present a framework nrITS tree of 235 accessions of Orchideae plus an in-depth analysis of 110 representative accessions, encompassing most widely recognized species within the alliance, to elucidate their relationships. Results We used parsimony, likelihood and Bayesian approaches to generate trees from data for two nuclear (rITS, low-copy Xdh) and four chloroplast (matK, psbA-trnH, trnL-F, trnS-trnG) markers. Nuclear and plastid data were analyzed separately due to a few hard incongruences that most likely reflect chloroplast capture. Our results suggest key phylogenetic placements for Sirindhornia and Brachycorythis, and confirm previous assertions that the Amitostigma alliance is monophyletic and sister to the Eurasian plus European clades of subtribe Orchidinae. Seven robust clades are evident within the alliance, but none corresponds precisely with any of the traditional genera; the smaller and more morphologically distinct genera Tsaiorchis, Hemipilia, Neottianthe and Hemipiliopsis are monophyletic but each is nested within a polyphyletic plexus of species attributed to either Ponerorchis or the most plesiomorphic genus, Amitostigma. Two early-divergent clades that escaped analysis by Jin et al. undermine their attempt to circumscribe an expanded monophyletic genus Ponerorchis. Conclusions We provide a new framework on the complex phylogenetic relationships between Amitostigma and other genera traditionally included in its alliance; based on which, we combine the entire Amitostigma alliance into a morphologically and molecularly circumscribed Amitostigma sensu latissimo that also contains seven molecularly circumscribed sections. Our molecular trees imply unusually high levels of morphological homoplasy, but these will need to be quantified via a future group-wide review of the alliance based on living plants if morphology is to be fully integrated into our classification.

Data from: Conserved genetic regions across angiosperms as tools to develop single copy nuclear markers in gymnosperms: an example using cycads

Several individuals of the Caribbean Zamia clade and other cycad genera were used to identify single copy nuclear genes for phylogeographic and phylogenetic studies in Cycadales. Two strategies were employed to select target loci: 1) a tblastX search of Arabidopsis conserved ortholog sequence (COS) set and, 2) a tblastX search of Arabidopsis-Populus-Vitis-Oryza Shared Single Copy genes (APVO SSC) against the EST Zamia databases in Genbank. From the first strategy, 30 loci were selected, and from the second, 16 loci. In both cases the matching Genbank accessions of Zamia were used as a query for retrieving highly similar sequences from Cycas, Picea, Pinus species or Ginko biloba. After retrieving and aligning all the sequences in each locus, intron predictions were completed to assist in primer design. PCR was carried out in three rounds to detect paralogous loci. A total of 29 loci were successfully amplified as a single band of which 20 were likely single copy loci. These loci showed different diversity and divergence levels. A preliminary screening allowed us to select 8 promising loci (40S, ATG2, BG, GroES, GTP, LiSH, PEX4 and TR) for the Z. pumila complex and 4 loci (COS26, GroES, GTP and HTS) for all other cycad genera.

opencc-zeroDec 2015View details →

Data from: Development of microsatellite markers for buffalograss (Buchloë dactyloides; Poaceae), a drought-tolerant turfgrass alternative

Premise of the study: Buchloë dactyloides is an important component of Great Plains prairies and a popular drought-tolerant turfgrass alternative in North America. This species comprises an autopolyploid series, and microsatellite primers were developed in order to understand the distribution of genetic variation among cytotypes and across its large geographic range. Methods and Results: Fifteen microsatellite loci were designed and successfully amplified in six B. dactyloides populations. Within-population genetic diversity was comparatively high, consistent with B. dactyloides' life history. Allelic variation at 13 loci was consistent with cytotype established in chromosome-counted samples. Conclusions: This variable, interpretable set of loci allows for the determination of multi-locus genotype in B. dactyloides individuals of varying cytotype. Data such as these from a range-wide sample set can provide important insights for germplasm conservation and crop improvement in this ecologically and economically important species.

Data from: A comparison of single nucleotide polymorphism and microsatellite markers for analysis of parentage and kinship in a cooperatively breeding bird

The development of genetic markers has revolutionized molecular studies within and among populations. Although poly-allelic microsatellites are the most commonly used genetic marker for within-population studies of free-living animals, biallelic single nucleotide polymorphisms, or SNPs, have also emerged as a viable option for use in nonmodel systems. We describe a robust method of SNP discovery from the transcriptome of a nonmodel organism that resulted in more than 99% of the markers working successfully during genotyping. We then compare the use of 102 novel SNPs with 15 previously developed microsatellites for studies of parentage and kinship in cooperatively breeding superb starlings (Lamprotornis superbus) that live in highly kin-structured groups. For 95% of the offspring surveyed, SNPs and microsatellites identified the same genetic father, but only when behavioural information about the likely parents at a nest was included to aid in assignment. Moreover, when such behavioural information was available, the number of SNPs necessary for successful parentage assignment was reduced by half. However, in a few cases where candidate fathers were highly related, SNPs did a better job at assigning fathers than microsatellites. Despite high variation between individual pairwise relatedness values, microsatellites and SNPs performed equally well in kinship analyses. This study is the first to compare SNPs and microsatellites for analyses of parentage and relatedness in a species that lives in groups with a complex social and kin structure. It should also prove informative for those interested in developing SNP loci from transcriptome data when published genomes are unavailable.

opencc-zeroDec 2015View details →

Data from: Population genetics of overwintering monarch butterflies, Danaus plexippus (Linnaeus), from central Mexico inferred from mitochondrial DNA and microsatellite markers

Population genetic variation and demographic history in Danaus plexippus (L.), from Mexico were assessed based on analyses of mitochondrial cytochrome c oxidase subunit I (COI; 658 bp) and subunit II (COII; 503 bp) gene segments and seven microsatellite loci. The sample of 133 individuals included both migratory monarchs, mainly from four overwintering sites within the Monarch Butterfly Biosphere Reserve (MBBR) in central Mexico (states of Michoacán and México), and a nonmigratory population from Irapuato, Guanajuato. Haplotype (h) and nucleotide (π) diversities were relatively low, averaging 0.466 and 0.00073, respectively, for COI, and 0.629 and 0.00245 for COII. Analysis of molecular variance (AMOVA) of the COI data set, which included additional GenBank sequences from a nonmigratory Costa Rican population, showed significant population structure between Mexican migratory monarchs and nonmigratory monarchs from both Mexico and Costa Rica, suggesting limited gene flow between the two behaviorally distinct groups. Interestingly, while the COI haplotype frequencies of the nonmigratory populations differed from the migratory, they were similar to each other, despite the great physical distance between them. Microsatellite analyses, however, suggested a lack of structure between the two groups, possibly owing to the number of significant deviations from Hardy Weinberg equilibrium resulting from heterzoygote deficiencies found for most of the loci. Estimates of demographic history of the combined migratory MBBR monarch population, based on the mismatch distribution and Bayesian skyline analyses of the concatenated COI and COII data set (n = 89) suggested a population expansion dating to the late Pleistocene (~35,000 to 40,000 years before present) followed by a stable effective female population size (Nef) of about six million over the last 10,000 years.

opencc-zeroDec 2015View details →

Data from: A comparative assessment of SNP and microsatellite markers for assigning parentage in a socially monogamous bird

Single-nucleotide polymorphisms (SNPs) are preferred over microsatellite markers in many evolutionary studies, but have only recently been applied to studies of parentage. Evaluations of SNPs and microsatellites for assigning parentage have mostly focused on special cases that require a relatively large number of heterozygous loci, such as species with low genetic diversity or with complex social structures. We developed 120 SNP markers from a transcriptome assembled using RNA-sequencing of a songbird with the most common avian mating system—social monogamy. We compared the effectiveness of 97 novel SNPs and six previously described microsatellites for assigning paternity in the black-throated blue warbler, Setophaga caerulescens. We show that the full panel of 97 SNPs (mean Ho = 0.19) was as powerful for assigning paternity as the panel of multiallelic microsatellites (mean Ho = 0.86). Paternity assignments using the two marker types were in agreement for 92% of the offspring. Filtering individual samples by a 50% call rate and SNPs by a 75% call rate maximized the number of offspring assigned with 95% confidence using SNPs. We also found that the 40 most heterozygous SNPs (mean Ho = 0.37) had similar power to assign paternity as the full panel of 97 SNPs. These findings demonstrate that a relatively small number of variable SNPs can be effective for parentage analyses in a socially monogamous species. We suggest that the development of SNP markers is advantageous for studies that require high-throughput genotyping or that plan to address a range of ecological and evolutionary questions.

Data from: Genome- and transcriptome-assisted development of nuclear insertion/deletion markers for Calanus species (Copepoda: Calanoida) identification

Copepods of the genus Calanus are key zooplankton species in temperate to arctic marine ecosystems. Despite their ecological importance, species identification remains challenging. Furthermore, the recent report of hybrids among Calanus species highlights the need for diagnostic nuclear markers in order to efficiently identify parental species and hybrids. Using Next Generation Sequencing analysis of both the genome and transcriptome from two sibling species, C. finmarchichus and C. glacialis, we developed a panel of 12 nuclear insertion/deletion markers. All the markers showed species specific amplicon length. Furthermore most of the markers were successfully amplified in other Calanus species allowing the molecular identification of C. helgolandicus, C hyperboreus and C. marshallae.

Data from: Multilocus microsatellite markers for molecular typing of Candida tropicalis isolates

Background: Candida tropicalis is considered to be the leading pathogen causing nosocomial fungemia and hepatosplenic fungal infections in patients with cancer, particularly those with leukemia. Microsatellite-based typing methods using sets of genetic markers have been developed and reported for population structure analysis of C. albicans, C. glabrata, and C. parapsilosis, but no studies have been published for genetic analysis of C. tropicalis. The objective of this study was to develop new microsatellite loci that have the ability to distinguish among C. tropicalis isolates. Results: DNA sequences containing over 10 bi- or tri-nucleotide repeats were selected from the C. tropicalis genome database. Thirty PCR primers sets specific for the microsatellite loci were designed and tested using eight clinically independent isolates. According to the amplification efficiency, specificity, and observed polymorphisms, eight markers were selected for further population structure analysis and molecular typing. Sixty-five independent C. tropicalis isolates were genotyped using these 8 markers. Based on these analyses, six microsatellite loci were confirmed, although two loci were found to be with unstable flanking areas. The six polymorphic loci displayed 4–22 alleles and 7–27 genotypes. The discriminatory power of the six loci ranged from 0.70 to 0.95. Genotyping results obtained by microsatellite analysis were compared to PCR-fingerprinting and multi-locus sequence typing (MLST). The comparisons showed that microsatellite analysis and MLST had the similar discriminatory power for C. tropicalis, which were more powerful than PCR-fingerprinting. Conclusions: This is the first attempt to develop new microsatellite loci for C. tropicalis. These newly developed markers will be a valuable resource for the differentiation of C. tropicalis isolates. More C. tropicalis isolates will need to be sequenced and analyzed in order to fully show the potential of these newly developed microsatellite markers.

Data from: Tracing the origins of Calanus sp. in the Saguenay‑St. Lawrence Marine Park (Québec, Canada) using δ13C as a marker

The Saguenay-St. Lawrence Marine Park (SSLMP) is a region that sustains a high abundance of zooplankton. The connectivity between zooplankton populations within the SSLMP and the surrounding areas was investigated for Calanus finmarchicus and C. hyperboreus. Deep-dwelling stage V copepodites (CVs) were collected in the Marine Park as well as in putative source regions in the St. Lawrence system in July 2009 (a time when they were entering into diapause). In May 2010, at the end of the overwintering period, diapausing CVs were sampled again in the Marine Park. To discriminate the origins and to predict the probable regions of origin of these deep-dwelling diapausing CVs in the SSLMP, a quadratic discriminant function analysis (QDFA) was performed. The classification algorithm was based on the carbon isotopic composition (δ13C) and percent carbon (%C) of individual copepods, as these variables are conservative when lipids are extracted prior to analysis. Our results suggest that about 23% of the Calanus spp. population sampled in SSLMP in late spring 2010 originated from the Saguenay Fjord (inside the SSLMP). The remainder of this population originated from regions outside the SSLMP, including the Lower St. Lawrence Estuary, and likely further east in the Gulf of St. Lawrence. Our results revealed high connectivity across the Saguenay and the St. Lawrence systems, as well as the potential for significant local production and recruitment of Calanus spp. within the Saguenay Fjord. This study also revealed the effectiveness of using δ13C as a marker in delineating the origin of Calanus spp., which has a relatively long non-feeding overwintering and diapausing period making it amenable to the conservation of isotopic signatures.

opencc-zeroDec 2011View details →

Data from: De novo characterization of the Timema cristinae transcriptome facilitates marker discovery and inference of genetic divergence.

Adaptation to different ecological environments can promote speciation. Although numerous examples of such 'ecological speciation' exist, the genomic basis of the process, and the role of gene flow in it, remains less understood. This is, at least in part, because systems that are well characterized in terms of their ecology often lack genomic resources. In this study we characterize the transcriptome of Timema cristinae stick insects, a system that has been researched intensively in terms of ecological speciation, but for which genomic resources have not been previously developed. Specifically, we obtained >1 million 454 sequencing reads that assembled into 84,937 contigs representing approximately 18,282 unique genes and tens of thousands of potential molecular markers. Second, as an illustration of their utility, we used these genomic resources to assess multi-locus genetic divergence within both an ecotype pair and a species pair of Timema stick insects. The results suggest variable levels of genetic divergence and gene flow among taxon pairs and genes and illustrate a first step towards future genomic work in Timema.

Data from: Relatedness severely impacts accuracy of marker- assisted selection for disease resistance in hybrid wheat

The accuracy of genomic selection depends on the relatedness between the members of the set in which marker effects are estimated based on evaluation data and the types for which performance is predicted. Here, we investigate the impact of relatedness on the performance of marker-assisted selection for fungal disease resistance in hybrid wheat. A large and diverse mapping population of 1,739 elite European winter wheat inbred lines and hybrids was evaluated for powdery mildew, leaf rust, and stripe rust resistance in multi-location field trials and fingerprinted with 9k and 90k SNP arrays. Comparison of the accuracies of prediction achieved with data sets from the two marker arrays revealed a crucial role for a sufficiently high marker density in genome-wide association mapping. Cross- validation studies using test sets with varying degrees of relationship to the corresponding estimation sets unraveled that close relatedness leads to a substantial increase in the proportion of total genotypic variance explained by the identified QTL and, consequently, to an overoptimistic judgment of the prospected precision of marker-assisted selection.

opencc-zeroDec 2018View details →

Data from: Can we rely on selected genetic markers for population identification? evidence from coastal Atlantic cod

The use of genetic markers under putative selection in population studies carries the potential for erroneous identification of populations and misassignment of individuals to population of origin. Selected markers are nevertheless attractive, especially in marine organisms that are characterized by weak population structure at neutral loci. Highly fecund species may tolerate the cost of strong selective mortality during early life stages, potentially leading to a shift in offspring genotypes away from the parental proportions. In Atlantic cod, recent genetic studies have uncovered different genotype clusters apparently representing phenotypically cryptic populations that coexist in coastal waters. Here, we tested if a high‐graded SNP panel specifically designed to classify individual cod to population of origin may be unreliable because of natural selection acting on the SNPs or their linked background. Temporal samples of cod were collected from two fjords, starting at the earliest life stage (pelagic eggs) and carried on until late autumn (bottom‐settled juveniles), covering the period during summer of high natural mortality. Despite the potential for selective mortality during the study period, we found no evidence for selection, as both cod types occurred throughout the season, already in the earliest egg samples, and there was no evidence for a shift during the season in the proportions of one or the other type. We conclude that high‐graded marker panels under putative natural selection represent a valid and useful tool for identifying biological population structure in this highly fecund species and presumably in others.

Data from: Mass production of SNP markers in a nonmodel passerine bird through RAD sequencing and contig mapping to the zebra finch genome

Here, we present an adaptation of restriction-site-associated DNA sequencing (RAD-seq) to the Illumina HiSeq2000 technology that we used to produce SNP markers in very large quantities at low cost per unit in the Réunion grey white-eye (Zosterops borbonicus), a nonmodel passerine bird species with no reference genome. We sequenced a set of six pools of 18–25 individuals using a single sequencing lane. This allowed us to build around 600 000 contigs, among which at least 386 000 could be mapped to the zebra finch (Taeniopygia guttata) genome. This yielded more than 80 000 SNPs that could be mapped unambiguously and are evenly distributed across the genome. Thus, our approach provides a good illustration of the high potential of paired-end RAD sequencing of pooled DNA samples combined with comparative assembly to the zebra finch genome to build large contigs and characterize vast numbers of informative SNPs in nonmodel passerine bird species in a very efficient and cost-effective way.