-
Integrated study on the topographic and shallow subsurface expression of the Grote Brogel Fault at the boundary of the Roer Valley Graben, Belgium
-
The Grote Brogel Fault (GBF) is a major WNW-ESE striking normal fault in Belgium that diverges westward from the NW-SE striking western border fault system of the Roer Valley Graben. The GBF delimits the topographically higher Campine Block from the subsiding Roer Valley Graben, and is expressed in the Digital Terrain Model (DTM) by relief gradients or scarps. By integrating DTM, Electrical Resistivity Tomography (ERT), Cone Penetration Test (CPT) and borehole data, we studied the Quaternary activity of the GBF and its effects on local hydrogeology. In the shallow subsurface (< 50 m) underneath these scarps, fault splays of the GBF were interpreted on newly acquired ERT profiles at two investigation sites: one on the eastern section and the other on the western section, near the limit of the visible surface trace of the fault. Borehole and CPT data enabled stratigraphic interpretations of the ERT profiles and thereby allowed measuring vertical fault offsets at the base of Pleistocene fluvial deposits of up to 12 m. Groundwater measurements in the boreholes and CPTs indicate that the GBF acts as a hydrologic boundary that prevents groundwater flow from the elevated footwall towards the hangingwall, resulting in hydraulic head differences of up to 12.7 m. For the two investigation sites, the hydraulic head changes correlate with the relief gradient, which in turn correlates with the Quaternary vertical offset of the GBF. ERT profiles at the eastern site also revealed a local soft-linked stepover in the shallow subsurface, which affects groundwater levels in the different fault blocks, and illustrates the complex small-scale geometry of the GBF.
Located in
Library
/
No RBINS Staff publications
-
Integration of landscape genomics, provenance trials and association mapping identifies genetic components underlying cold hardiness adaptation for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii)
-
Located in
Library
/
RBINS Staff Publications 2018
-
Integrative species delimitation and phylogeny of the branchiate worm Branchiodrilus (Clitellata, Naididae)
-
Located in
Library
/
RBINS Staff Publications 2018
-
Integrative taxonomic re-description of Halisarca magellanica and description of a new species of Halisarca (Porifera, Demospongiae) from Chilean Patagonia
-
Located in
Library
/
RBINS Staff Publications 2016
-
Integrative taxonomy of calcareous sponges (subclass Calcinea) from the Peruvian coast: morphology, molecules, and biogeography
-
Understanding of evolution and systematics of Calcarea (Porifera) have not yet met a corresponding increase in the knowledge of diversity and distribution of these sponges in several parts of the world. Peru is an emblematic example of this lack of taxonomic knowledge, as only three shallow-water species of sponges have hitherto been reported from its 3000 km coast. With the aim of studying sponges of Peru, an integrative taxonomy approach (morphology, molecules, and biogeography) was used in order to achieve sound species identifications. The first findings of Peruvian calcareous sponges are presented here. Eight species are described in the subclass Calcinea, of which five are new to science. The retrieved biogeographical patterns are either locally endemic, widespread, or discontinuous over large areas. Clathrina antofagastensis was previously known from Chile, while C. aurea and Ernstia tetractina had been reported from the Atlantic (Brazil), and thus represent the first genetically confirmed tropical amphi- American distributions of species not yet found on both sides of the Isthmus of Panama. Our results reveal a richer Tropical East Pacific sponge fauna than the Warm Temperate South-Eastern Pacific one.
Located in
Library
/
RBINS Staff Publications
-
Integrative taxonomy of giant crested Eusirus in the Southern Ocean, including the description of a new species (Crustacea: Amphipoda: Eusiridae)
-
Among Antarctic amphipods of the genus Eusirus, a highly distinctive clade of giant species is characterized by a dorsal, blade-shaped tooth on pereionites 5–7 and pleonites 1–3. This lineage, herein named ‘crested Eusirus’, includes two potential species complexes, the Eusirus perdentatus and Eusirus giganteus complexes, in addition to the more distinctive Eusirus propeperdentatus. Molecular phylogenies and statistical parsimony networks (COI, CytB and ITS2)of crested Eusirus are herein reconstructed. This study aims to formally revise species diversity within crested Eusirus by applying several species delimitation methods (Bayesian implementation of the Poisson tree processes model, general mixed Yule coalescent, multi-rate Poisson tree processes and automatic barcode gap discovery) on the resulting phylogenies. In addition, results from the DNA-based methods are benchmarked against a detailed morphological analysis of all available specimens of the E. perdentatus complex. Our results indicate that species diversity of crested Eusirus is underestimated. Overall, DNA-based methods suggest that the E. perdentatus complex is composed of three putative species and that the E. giganteus complex includes four or five putative species. The morphological analysis of available specimens from the E. perdentatus complex corroborates molecular results by identifying two differentiable species, the genuine E. perdentatus and a new species, herein described as Eusirus pontomedon sp. nov. ADDITIONAL KEYWORDS: alpha taxonomy – cryptic species – genetics – molecular systematics – phylogenetic systematics.
Located in
Library
/
RBINS Staff Publications 2020
-
Integrative taxonomy of the new millipede genus Coxobolellus, gen. nov. (Diplopoda : Spirobolida : Pseudospirobolellidae), with descriptions of ten new species
-
Located in
Library
/
RBINS Staff Publications 2020
-
Integrative taxonomy resuscitates two species in the Lasioglossum villosulum complex (Kirby, 1802) (Hymenoptera: Apoidea: Halictidae)
-
Located in
Library
/
RBINS Staff Publications 2018
-
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites
-
This study explores the petrology of five giant (>400 μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a range of criteria, previously defined for use on hydrated chondrites, including phyllosilicate fraction, matrix geochemistry and micro textures. Collectively, these micrometeorites represent ∼2.22 mm2 of intensely altered hydrated chondritic matrix (with petrologic subtypes of <1.2 in the scheme of Howard et al. (2015)) and reveal a range of alteration styles. Two particles are found to contain pseudomorphic chondrules with thick fine-grained rims, while another micrometeorite contains several aqueously altered CAIs. Their outlines range from well-defined to indistinct, demonstrating that the advanced stages of aqueous alteration progressively remove evidence of coarse-grained components. The remaining two micrometeorites entirely lack coarse-grained components but are similarly altered. Thus, the combined chondrule-to-matrix ratio among these giant micrometeorites is extremely low (6.45 area%), and significantly below the average ratio found in typical CM or CR chondrites (∼20%, Weisberg et al., 2006). Our findings are consistent with previous analyses from smaller Antarctic micrometeorites, which suggest that chondrules (and CAIs) derived from hydrated carbonaceous chondrite parent bodies are underrepresented among the micrometeorite flux, even when considering contributions from coarse-grained micrometeorites. Therefore, to explain the relative paucity of anhydrous material, we propose that the flux of fine-grained micrometeorites is primarily derived from intensely aqueously altered, primitive C-type asteroids, which have lost the majority of their refractory coarse-grained components by replacement with secondary phyllosilicate minerals.
Located in
Library
/
RBINS Staff Publications 2019
-
Inter and intra island introgression in a wolf spider radiation from the Galapagos and its implications for parallel evolution
-
Parallel radiations within island systems are often assumed to follow a simple scenario in which single colonization events are followed by in situ adaptive divergence. However, subsequent gene exchange after the initial colonization and during the divergence process might have important evolutionary impacts on species radiations. Gene exchange among ecologically similar species from different islands may lead to introgression of adaptive genetic variation and influence the parallel divergence process. In this study, we estimate levels of gene exchange within a wolf spider radiation of the genus Hogna Simon, 1885, from the Galápagos, wherein habitat specialization into ‘high elevation’ and ‘coastal dry’ species apparently evolved repeatedly on two islands. By using a multilocus approach we show that low levels of inter-island and relatively higher levels of intra island introgression shaped genetic variation in this species complex. Using these estimates, we demonstrate by means of a coalescence simulation that under these inter- and intra-island migration rates parallel evolution most likely evolves by introgression of adaptive alleles among islands, rather than through independent mutations despite the close genetic relationship of species within islands. As species phylogenies within radiations are frequently used to infer the divergence pattern, even relatively low levels of interspecific gene flow should not be neglected when interpreting parallel trait evolution.
Located in
Library
/
RBINS Staff Publications
