• Climatic oscillations in Quaternary have shaped the co‑evolutionary patterns between the Norway spruce and its host‑associated herbivore

      Jakub, G; Andrzej, O; Robert, R; Igor, C; Katarzyna, M; Radosław, P; Matti, L; Mauro, G; Gernot, H; Vytautas, T; et al. (Springer Nature, 2020-10-05)
      During the Last Glacial Maximum in the Northern Hemisphere, expanding ice sheets forced a large number of plants, including trees, to retreat from their primary distribution areas. Many host-associated herbivores migrated along with their host plants. Long-lasting geographic isolation between glacial refugia could have been led to the allopatric speciation in separated populations. Here, we have studied whether the migration history of the Norway spruce Picea abies in Quaternary has affected its host-associated herbivorous beetle—Monochamus sartor. By using microsatellite markers accompanied by the geometric morphometrics analysis of wing venation, we have revealed the clear geographic structure of M. sartor in Eurasia, encompassing two main clusters: southern (Alpine–Carpathian) and eastern (including northeastern Europe and Asia), which reflects the northern and southern ecotypes of its host. The two beetles’ lineages probably diverged during the Pleniglacial (57,000—15,000 BC) when their host tree species was undergoing significant range fragmentation and experienced secondary contact during post-glacial recolonization of spruce in the Holocene. A secondary contact of divergent lineages of M. sartor has resulted in the formation of the hybrid zone in northeastern Europe. Our findings suggest that the climatic oscillations during the Pleistocene have driven an insect-plant co-evolutionary process, and have contributed to the formation of the unique biodiversity of Europe.
    • Mitogenomics of historical type specimens of Australasian turtles: clarification of taxonomic confusion and old mitochondrial introgression

      Kehlmaier, C; Zhang, X; Georges, A; Campbell, P; Thomson, S; Fritz, U (Springer Nature, 2019-04-09)
      Diagnosability is central to taxonomy as are type specimens which define taxa. New advances in technologies and the discovery of new informative traits must be matched with previous taxonomic decisions based on name-bearing type specimens. Consequently, the challenge of sequencing highly degraded DNA from historical types becomes an inevitability to resolve the very many taxonomic issues arising from, by modern standards, poor historical species descriptions leading to difficulties to assign names to genetic clusters identified from fresh material. Here we apply high-throughput parallel sequencing and sequence baiting to reconstruct the mitogenomes from 18 type specimens of Australasian side-necked turtles (Chelidae). We resolve a number of important issues that have confused the taxonomy of this family, and analyse the mitogenomes of the types and those of fresh material to improve our understanding of the phylogenetic relationships of this morphologically conservative group. Together with previously published nuclear genomic data, our study provides evidence for multiple old mitochondrial introgressions.
    • Molecular characterization and distribution of Schistosoma cercariae collected from naturally infected bulinid snails in northern and central Côte d’Ivoire

      Tian-Bi, Y-NT; Webster, BL; Konan, CK; Allan, F; Diakité, NR; Ouattara, M; Salia, D; Koné, A; Kakou, AK; Rabone, M; et al. (Springer Nature, 2019-03-19)
      Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d’Ivoire and confirmed the presence of interspecific hybrid schistosomes. Methods Between June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d’Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification. Results Overall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii were obtained. Among 2417 Bulinus screened, 25 specimens (18 B. truncatus and seven B. globosus) shed schistosomes, with up to 14% infection prevalence per site and time point. Globally, infection rates per time point ranged between 0.6 and 4%. Schistosoma bovis, S. haematobium and S. bovis × S. haematobium hybrids infected 0.5%, 0.2% and 0.4% of the snails screened, respectively. Schistosoma bovis and hybrids were more prevalent in B. truncatus, whereas S. haematobium and hybrid infections were more prevalent in B. globosus. Schistosoma bovis-infected Bulinus were predominantly found in northern sites, while S. haematobium and hybrid infected snails were mainly found in central parts of Côte d’Ivoire. Conclusions The data highlight the necessity of using molecular tools to identify and understand which schistosome species are transmitted by specific intermediate host snails. The study deepens our understanding of the epidemiology and transmission dynamics of S. haematobium and S. bovis in Côte d’Ivoire and provides the first conclusive evidence for the transmission of S. haematobium × S. bovis hybrids in this West African country. Trial registration ISRCTN, ISRCTN10926858. Registered 21 December 2016; retrospectively registered (see: http://www.isrctn.com/ISRCTN10926858)
    • Significant variance in genetic diversity among populations of Schistosoma haematobium detected using microsatellite DNA loci from a genome-wide database

      Glenn, TC; Lance, SL; McKee, AM; Webster, BL; Emery, AM; Zerlotini, A; Oliveira, G; Rollinson, D; Faircloth, BC (Springer Nature, 2013)
      Background Urogenital schistosomiasis caused by Schistosoma haematobium is widely distributed across Africa and is increasingly being targeted for control. Genome sequences and population genetic parameters can give insight into the potential for population- or species-level drug resistance. Microsatellite DNA loci are genetic markers in wide use by Schistosoma researchers, but there are few primers available for S. haematobium. Methods We sequenced 1,058,114 random DNA fragments from clonal cercariae collected from a snail infected with a single Schistosoma haematobium miracidium. We assembled and aligned the S. haematobium sequences to the genomes of S. mansoni and S. japonicum, identifying microsatellite DNA loci across all three species and designing primers to amplify the loci in S. haematobium. To validate our primers, we screened 32 randomly selected primer pairs with population samples of S. haematobium. Results We designed >13,790 primer pairs to amplify unique microsatellite loci in S. haematobium, (available at http://www.cebio.org/projetos/schistosoma-haematobium-genome). The three Schistosoma genomes contained similar overall frequencies of microsatellites, but the frequency and length distributions of specific motifs differed among species. We identified 15 primer pairs that amplified consistently and were easily scored. We genotyped these 15 loci in S. haematobium individuals from six locations: Zanzibar had the highest levels of diversity; Malawi, Mauritius, Nigeria, and Senegal were nearly as diverse; but the sample from South Africa was much less diverse. Conclusions About half of the primers in the database of Schistosoma haematobium microsatellite DNA loci should yield amplifiable and easily scored polymorphic markers, thus providing thousands of potential markers. Sequence conservation among S. haematobium, S. japonicum, and S. mansoni is relatively high, thus it should now be possible to identify markers that are universal among Schistosoma species (i.e., using DNA sequences conserved among species), as well as other markers that are specific to species or species-groups (i.e., using DNA sequences that differ among species). Full genome-sequencing of additional species and specimens of S. haematobium, S. japonicum, and S. mansoni is desirable to better characterize differences within and among these species, to develop additional genetic markers, and to examine genes as well as conserved non-coding elements associated with drug resistance.
    • Triggers for the formation of porphyry ore deposits in magmatic arcs

      Wilkinson, JJ (Springer Nature, 2013-10-13)
      Porphyry ore deposits are the source of much of the copper, molybdenum, gold and silver used by humans. Porphyry ore typically forms in magmatic arcs above subduction zones. However, generation of the largest deposits is often restricted to specific arc segments and limited periods of time. Here, I outline a hierarchy of four key triggers that may be involved in the formation of large porphyry deposits. The first process is characterized by a cyclical enrichment of magmas with metals and water in the deep crust. Second, saturation of the magma with sulphide facilitates the concentration of metals into smaller volumes of material from which they can later be released. The third process is an efficient transfer of metals into hydrothermal fluids that are exsolved from the magmas. Finally, localized processes trigger the precipitation of ore minerals in the crust. Although some or all of these processes must act in concert to generate large ore deposits, I argue that sulphide saturation of the magma is the most important step and that this can explain the temporal and spatial distribution of ores. Consequently, the fingerprint of sulphide saturation in igneous rocks could be used to identify those parts of magmatic arcs that are particularly predisposed to ore formation.