Introgressive hybridization and the evolutionary history of the herring gull complex revealed by mitochondrial and nuclear DNA

<p>Abstract</p> <p>Background</p> <p>Based on extensive mitochondrial DNA (mtDNA) sequence data, we previously showed that the model of speciation among species of herring gull (<it>Larus argentatus</it>) complex was not that of a ring species, but most likely due more complex speciation scenario's. We also found that two species, herring gull and glaucous gull (<it>L. hyperboreus</it>) displayed an unexpected biphyletic distribution of their mtDNA haplotypes. It was evident that mtDNA sequence data alone were far from sufficient to obtain a more accurate and detailed insight into the demographic processes that underlie speciation of this complex, and that extensive autosomal genetic analysis was warranted.</p> <p>Results</p> <p>For this reason, the present study focuses on the reconstruction of the phylogeographic history of a limited number of gull species by means of a combined approach of mtDNA sequence data and 230 autosomal amplified fragment length polymorphism (AFLP) loci. At the species level, the mtDNA and AFLP genetic data were largely congruent. Not only for <it>argentatus </it>and <it>hyperboreus</it>, but also among a third species, great black-backed gull (<it>L. marinus</it>) we observed two distinct groups of mtDNA sequence haplotypes. Based on the AFLP data we were also able to detect distinct genetic subgroups among the various <it>argentatus</it>, <it>hyperboreus</it>, and <it>marinus </it>populations, supporting our initial hypothesis that complex demographic scenario's underlie speciation in the herring gull complex.</p> <p>Conclusions</p> <p>We present evidence that for each of these three biphyletic gull species, extensive mtDNA introgression could have taken place among the various geographically distinct subpopulations, or even among current species. Moreover, based on a large number of autosomal AFLP loci, we found evidence for distinct and complex demographic scenario's for each of the three species we studied. A more refined insight into the exact phylogeographic history within the herring gull complex is still impossible, and requires detailed autosomal sequence information, a topic of our future studies.</p

Proportioning whole-genome single-nucleotide-polymorphism diversity for the identification of geographic population structure and genetic ancestry

The identification of geographic population structure and genetic ancestry on the basis of a minimal set of genetic markers is desirable for a wide range of applications in medical and forensic sciences. However, the absence of sharp discontinuities in the neutral genetic diversity among human populations implies that, in practice, a large number of neutral markers will be required to identify the genetic ancestry of one individual. We showed that it is possible to reduce the amount of markers required for detecting continental population structure to only 10 single-nucleotide polymorphisms (SNPs), by applying a newly developed ascertainment algorithm to Affymetrix GeneChip Mapping 10K SNP array data that we obtained from samples of globally dispersed human individuals (the Y Chromosome Consortium panel). Furthermore, this set of SNPs was able to recover the genetic ancestry of individuals from all four continents represented in the original data set when applied to an independent, much larger, worldwide population data set (Centre d'Etude du Polymorphisme Humain-Human Genome Diversity Project Cell Line Panel). Finally, we provide evidence that the unusual patterns of genetic variation we observed at the respective genomic regions surrounding the five most informative SNPs is in agreement with local positive selection being the explanation for the striking SNP allele-frequency differences we found between continental groups of human populations

Developing a set of ancestry-sensitive DNA markers reflecting continental origins of humans

Background: The identification and use of Ancestry-Sensitive Markers (ASMs), i.e. genetic polymorphisms facilitating the genetic reconstruction of geographical origins of individuals, is far from straightforward. Results: Here we describe the ascertainment and application of five different sets of 47 single nucleotide polymorphisms (SNPs) allowing the inference of major human groups of different continental origin. For this, we first used 74 cell lines, representing human males from six different geographical areas and screened them with the Affymetrix Mapping 10K assay. In addition to using summary statistics estimating the genetic diversity among multiple groups of individuals defined by geography or language, we also used the program STRUCTURE to detect genetically distinct subgroups. Subsequently, we used a pairwise FSTranking procedure among all pairs of genetic subgroups in order to identify a single best performing set of ASMs. Our initial results were independently confirmed by genotyping this set of ASMs in 22 individuals from Somalia, Afghanistan and Sudan and in 919 samples from the CEPH Human Genome Diversity Panel (HGDP-CEPH). Conclusion: By means of our pairwise population FSTranking approach we identified a set of 47 SNPs that could serve as a panel of ASMs at a continental level

A sensitive method to extract DNA from biological traces present on ammunition for the purpose of genetic profiling

Exploring technological limits is a common practice in forensic DNA research. Reliable genetic profiling based on only a few cells isolated from trace material retrieved from a crime scene is nowadays more and more the rule rather than the exception. On many crime scenes, cartridges, bullets, and casings (jointly abbreviated as CBCs) are regularly found, and even after firing, these potentially carry trace amounts of biological material. Since 2003, the Forensic Laboratory for DNA Research is routinely involved in the forensic investigation of CBCs in the Netherlands. Reliable DNA profiles were frequently obtained from CBCs and used to match suspects, victims, or other crime scene-related DNA traces. In this paper, we describe the sensitive method developed by us to extract DNA from CBCs. Using PCR-based genotyping of autosomal short tandem repeats, we were able to obtain reliable and reproducible DNA profiles in 163 out of 616 criminal cases (26.5%) and in 283 out of 4,085 individual CBC items (6.9%) during the period January 2003–December 2009. We discuss practical aspects of the method and the sometimes unexpected effects of using cell lysis buffer on the subsequent investigation of striation patterns on CBCs

DNA metabarcoding quantifies the relative biomass of arthropod taxa in songbird diets:Validation with camera-recorded diets

Ecological research is often hampered by the inability to quantify animal diets. Diet composition can be tracked through DNA metabarcoding of fecal samples, but whether (complex) diets can be quantitatively determined with metabarcoding is still debated and needs validation using free-living animals. This study validates that DNA metabarcoding of feces can retrieve actual ingested taxa, and most importantly, that read numbers retrieved from sequencing can also be used to quantify the relative biomass of dietary taxa. Validation was done with the hole-nesting insectivorous Pied Flycatcher whose diet was quantified using camera footage. Size-adjusted counts of food items delivered to nestlings were used as a proxy for provided biomass of prey orders and families, and subsequently, nestling feces were assessed through DNA metabarcoding. To explore potential effects of digestion, gizzard and lower intestine samples of freshly collected birds were subjected to DNA metabarcoding. For metabarcoding with Cytochrome Oxidase subunit I (COI), we modified published invertebrate COI primers LCO1490 and HCO1777, which reduced host reads to 0.03%, and amplified Arachnida DNA without significant changing the recovery of other arthropod taxa. DNA metabarcoding retrieved all commonly camera-recorded taxa. Overall, and in each replicate year (N = 3), the relative scaled biomass of prey taxa and COI read numbers correlated at R =.85 (95CI:0.68–0.94) at order level and at R =.75 (CI:0.67–0.82) at family level. Similarity in arthropod community composition between gizzard and intestines suggested limited digestive bias. This DNA metabarcoding validation demonstrates that quantitative analyses of arthropod diet is possible. We discuss the ecological applications for insectivorous birds

Determining the quality and complexity of next-generation sequencing data without a reference genome

Genomics, epigenetics, population genetics and bioinformatic

Deciduous Teeth as an Alternative DNA Source for Postmortem Genetic Testing

Contains fulltext : 220426.pdf (Publisher’s version ) (Closed access

Genetic heterogeneity in regional populations of Quebec : parental lineages in the Gaspe Peninsula

Stable colonization of the Gaspe Peninsula by Europeans started in the middle of the 18th century at the time of the British conquest of New France. The earliest settlers were Acadians, escaping British deportation policies, followed by Loyalists from the US, who preferred to remain under British rule after the Declaration of Independence. In the 19th century, the developing fishing industry attracted French Canadians from the St. Lawrence Valley and newcomers from Europe including Channel Islanders from Jersey and Guernsey. We analyzed parental lineages of the self-declared descendants of these four groups of settlers by mtDNA D-loop sequencing and Y-chromosome genotyping and compared them with French, British, and Irish samples. Their representation in terms of haplotype frequency classes reveals different signatures of founder effects, such as a loss of rare haplotypes, modification of intermediate frequency haplotypes, reduction in genetic diversity (seen in Acadians), but also enrichment by admixture. Parental lineages correlate with group identity. Descendants of early settlers, Acadians and Loyalists, preserved their identity more than those of French Canadian and Channel Islander “latecomers.” Although overall genetic diversity among Gaspesians is comparable with their European source populations, FST analysis indicated their greater differentiation. Distinct settlement history, a limited number of founders and relative genetic isolation contributed to the regionalization of the Quebec gene pool that appears less homogenous than usually anticipated

The HIrisPlex-S system for eye, hair and skin colour prediction from DNA: Introduction and forensic developmental validation

Forensic DNA Phenotyping (FDP), i.e. the prediction of human externally visible traits from DNA, has become a fast growing subfield within forensic genetics due to the intelligence information it can provide from DNA traces. FDP outcomes can help focus police investigations in search of unknown perpetrators, who are generally unidentifiable with standard DNA profiling. Therefore, we previously developed and forensically validated the IrisPlex DNA test system for eye colour prediction and the HIrisPlex system for combined eye and hair colour prediction from DNA traces. Here we introduce and forensically validate the HIrisPlex-S DNA test system (S for skin) for the simultaneous prediction of eye, hair, and skin colour from trace DNA. This FDP system consists of two SNaPshot-based multiplex assays targeting a total of 41 SNPs via a novel multiplex assay for 17 skin colour predictive SNPs and the previous HIrisPlex assay for 24 eye and hair colour predictive SNPs, 19 of which also contribute to skin colour prediction. The HIrisPlex-S system further comprises three statistical prediction models, the previously developed IrisPlex model for eye colour prediction based on 6 SNPs, the previous HIrisPlex model for hair colour prediction based on 22 SNPs, and the recently introduced HIrisPlex-S model for skin colour prediction based on 36 SNPs. In the forensic developmental validation testing, the novel 17-plex assay performed in full agreement with the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, as previously shown for the 24-plex assay. Sensitivity testing of the 17-plex assay revealed complete SNP profiles from as little as 63 pg of input DNA, equalling the previously demonstrated sensitivity threshold of the 24-plex HIrisPlex assay. Testing of simulated forensic casework samples such as blood, semen, saliva stains, of inhibited DNA samples, of low quantity touch (trace) DNA samples, and of artificially degraded DNA samples as well as concordance testing, demonstrated the robustness, efficiency, and forensic suitability of the new 17-plex assay, as previously shown for the 24-plex assay. Finally, we provide an update of the publically available HIrisPlex website https://hirisplex.erasmusmc.nl/, now allowing the estimation of individual probabilities for 3 eye, 4 hair, and 5 skin colour categories from HIrisPlex-S input genotypes. The HIrisPlex-S DNA test represents the first forensically validated tool for skin colour prediction, and reflects the first forensically validated tool for simultaneous eye, hair and skin colour prediction from DNA