47 research outputs found
Optical, magneto-optical properties and fiber-drawing ability of tellurite glasses in the TeO2-ZnO-BaO ternary system
The presented work is focused on the optical and magneto-optical
characterization of TeO2-ZnO-BaO (TZB) tellurite glasses. We investigated the
refractive index and extinction coefficient dispersion by spectroscopic
ellipsometry from ultraviolet, 0.193 um, up to mid infrared, 25 um spectral
region. Studied glasses exhibited large values of linear (n632 = 1.91-2.09) and
non-linear refractive index (n2 = 1.20-2.67x10-11 esu), Verdet constant (V632 =
22-33 radT-1m-1) and optical band gap energy (Eg = 3.7-4.1 eV). The materials
characterization revealed that BaO substitution by ZnO leads (at constant
content of TeO2) to an increase in linear and nonlinear refractive index as
well as Verdet constant while the optical band gap energy decreases. Fiber
drawing ability of TeO2-ZnO-BaO glassy system has been demonstrated on
60TeO2-20ZnO-20BaO glass with presented mid infrared attenuation coefficient.
Specific parameters such as dispersion and single oscillator energy, Abbe
number, and first-/ third-order optical susceptibility are enclosed together
with the values of magneto-optic anomaly derived from the calculation of
measured dispersion of the refractive index
Genetic Differentiation of the Western Capercaillie Highlights the Importance of South-Eastern Europe for Understanding the Species Phylogeography
The Western Capercaillie (Tetrao urogallus L.) is a grouse species of open boreal or high altitude forests of Eurasia. It is endangered throughout most mountain range habitat areas in Europe. Two major genetically identifiable lineages of Western Capercaillie have been described to date: the southern lineage at the species' southernmost range of distribution in Europe, and the boreal lineage. We address the question of genetic differentiation of capercaillie populations from the Rhodope and Rila Mountains in Bulgaria, across the Dinaric Mountains to the Slovenian Alps. The two lineages' contact zone and resulting conservation strategies in this so-far understudied area of distribution have not been previously determined. The results of analysis of mitochondrial DNA control region sequences of 319 samples from the studied populations show that Alpine populations were composed exclusively of boreal lineage; Dinaric populations of both, but predominantly (96%) of boreal lineage; and Rhodope-Rila populations predominantly (>90%) of southern lineage individuals. The Bulgarian mountains were identified as the core area of the southern lineage, and the Dinaric Mountains as the western contact zone between both lineages in the Balkans. Bulgarian populations appeared genetically distinct from Alpine and Dinaric populations and exhibited characteristics of a long-term stationary population, suggesting that they should be considered as a glacial relict and probably a distinct subspecies. Although all of the studied populations suffered a decline in the past, the significantly lower level of genetic diversity when compared with the neighbouring Alpine and Bulgarian populations suggests that the isolated Dinaric capercaillie is particularly vulnerable to continuing population decline. The results are discussed in the context of conservation of the species in the Balkans, its principal threats and legal protection status. Potential conservation strategies should consider the existence of the two lineages and their vulnerable Dinaric contact zone and support the specificities of the populations
The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics.
ABSTRACT: A global genome database of all of Earth’s species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic information available. To contribute to a more complete planetary genomic database, scientists and institutions across the world have united under the Earth BioGenome Project (EBP), which plans to sequence and assemble high-quality reference genomes for all ∼1.5 million recognized eukaryotic species through a stepwise phased approach. As the initiative transitions into Phase II, where 150,000 species are to be sequenced in just four years, worldwide participation in the project will be fundamental to success. As the European node of the EBP, the European Reference Genome Atlas (ERGA) seeks to implement a new decentralised, accessible, equitable and inclusive model for producing high-quality reference genomes, which will inform EBP as it scales. To embark on this mission, ERGA launched a Pilot Project to establish a network across Europe to develop and test the first infrastructure of its kind for the coordinated and distributed reference genome production on 98 European eukaryotic species from sample providers across 33 European countries. Here we outline the process and challenges faced during the development of a pilot infrastructure for the production of reference genome resources, and explore the effectiveness of this approach in terms of high-quality reference genome production, considering also equity and inclusion. The outcomes and lessons learned during this pilot provide a solid foundation for ERGA while offering key learnings to other transnational and national genomic resource projects.info:eu-repo/semantics/publishedVersio
The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics
A genomic database of all Earth’s eukaryotic species could contribute to many scientific discoveries; however, only a tiny fraction of species have genomic information available. In 2018, scientists across the world united under the Earth BioGenome Project (EBP), aiming to produce a database of high-quality reference genomes containing all ~1.5 million recognized eukaryotic species. As the European node of the EBP, the European Reference Genome Atlas (ERGA) sought to implement a new decentralised, equitable and inclusive model for producing reference genomes. For this, ERGA launched a Pilot Project establishing the first distributed reference genome production infrastructure and testing it on 98 eukaryotic species from 33 European countries. Here we outline the infrastructure and explore its effectiveness for scaling high-quality reference genome production, whilst considering equity and inclusion. The outcomes and lessons learned provide a solid foundation for ERGA while offering key learnings to other transnational, national genomic resource projects and the EBP.info:eu-repo/semantics/publishedVersio
Phylogeography of the rare Balkan endemic Martino's vole, Dinaromys bogdanovi, reveals strong differentiation within the western Balkan Peninsula
The spatial genetic structure of Martino's vole, a rare palaeoendemic species of the western Balkans, was investigated using DNA isolated from archived museum samples. The study was based on partial sequencing (555 bp) of the mitochondrial cytochrome b gene for 63 specimens from 20 different localities throughout the species' range. Three highly divergent allopatric phylogenetic lineages (Northwestern, Central and Southeastern) were recognized among 47 haplotypes, suggesting three independent glacial differentiation centres within the western Balkans. The Northwestern lineage, which showed the highest divergence from all other samples (mean sequence divergence of 6.64% +/- 1.10), comprised samples collected from northwest of the Neretva River in Croatia, western Bosnia and Herzegovina. The Central and Southeastern lineages were separated by an average sequence divergence of 2.95% +/- 0.66 and were geographically divided by the Drim River (the Kosovo Basin in Serbia). Overall, haplotype diversity decreased from the Northwestern lineage to the Central and subsequently the Southeastern lineage, in a geographical pattern consistent with a stepping stone colonization. The observed distribution indicates a gradual southerly expansion with subsequent allopatry across the Neretva River and Drim River approximately 1 and 0.3 million years ago, respectively. Such a scenario is concordant with palaeontological evidence. Several highly divergent sublineages within the Northwestern and Central lineages showed no significant geographical structuring, suggesting secondary contact of allopatrically evolved lineages. We hypothesize that the topographical complexity of the Balkans promoted allopatry and isolation on a small geographical scale during interglacial periods, with secondary contact during glacial maxima. Furthermore, the three main lineages should be regarded as evolutionary significant units with important implications for conservation. Ecological data show that the Northwestern lineage in particular fulfils all criteria for a highly endangered, evolutionarily significant unit
Age determination and age structure in the edible dormouse Glis glis based on incremental bone lines
Molecular systematics and evolutionary biogeography of the genus Talpa (Soricomorpha: Talpidae)
The range of the genus Talpa covers almost all Europe up to Western Asia. This genus has never been the object of comprehensive systematic studies using molecular and genetic techniques, such that the evolutionary relationships among species remain unclear. Talpa shows high levels of endemism, and the influence of past glaciation cycles on the distribution pattern of several species has been hypothesized. In this work, we assessed the molecular systematics of the genus using the mitochondrial gene cytochrome b from eight of the nine extant species of Talpa moles. Furthermore, molecular clock estimations were used to hypothesize a biogeographic scenario in concordance with fossil data. Results suggest a monophyletic origin of the genus and a common ancestor for the western European moles T. europaea, T. caeca, T. romana and T. occidentalis. The eastern species T. altaica and T. caucasica are basally divergent. The estimated ages of divergence among lineages are in accordance with a Miocene origin of the extant moles. The genus likely originated in Asia, spreading into Europe during the Pliocene. The evolution of moles appears to have been driven by changes in moisture levels that influenced extinction and speciation events during the Miocene and the Pliocene. Pleistocene climatic oscillations likely caused the range shrinkages and expansions that led to the current distribution pattern of most Talpa species. (C) 2010 Elsevier Inc. All rights reserved
Genetic structure of a European forest species, the edible dormouse ( Glis glis ): a consequence of past anthropogenic forest fragmentation?
International audienceThe genetic structure of forest animal species may allow the spatial dynamics of the forests themselves to be tracked. Two scales of change are commonly discussed: changes in forest distribution during the Quaternary, due to glacial/interglacial cycles, and current fragmentation related to habitat destruction. However, anthropogenic changes in forest distribution may have started well before the Quaternary, causing fragmentation at an intermediate time scale that is seldom considered. To explore the relative role of these processes, the genetic structure of a forest species with narrow ecological preferences, the edible dormouse (Glis glis), was investigated in a set of samples covering a large part of its Palaearctic distribution. Strong and complex geographical structure was revealed from the use of microsatellite markers. This structure suggests that fragmentation occurred in several steps, progressively splitting the ancestral population into peripheral isolated ones. The fact that this structure postdates post-glacial recolonization, together with dating based on microsatellite data, supports the hypothesis that the differentiation was recent, starting around 9000 years ago, and took place stepwise, possibly up to Medieval times. This complements a classic phylogeographical interpretation based on the effect of past climate change, and supports the role of anthropogenic deforestation as a trigger of recent intraspecific differentiation
Consequence of past anthropogenic forest fragmentation on the genetic structure of European mammals: the example of the edible dormouse (Glis glis)
The genetic structure of forest animal species may allow the spatial dynamics of the forests themselves to be tracked.
Two scales of change are commonly discussed: changes in forest distribution during the Quaternary, due to glacial/
interglacial cycles, and current fragmentation related to habitat destruction. However, anthropogenic changes in
forest distribution may have started well before the Quaternary, causing fragmentation at an intermediate time
scale that is seldom considered. To explore the relative role of these processes, the genetic structure of a forest
species with narrow ecological preferences, the edible dormouse (Glis glis), was investigated in a set of samples
covering a large part of its Palaearctic distribution. Strong and complex geographical structure was revealed from
the use of microsatellite markers. This structure suggests that fragmentation occurred in several steps, progressively
splitting the ancestral population into peripheral isolated ones. The fact that this structure postdates post-glacial
recolonization, together with dating based on microsatellite data, supports the hypothesis that the differentiation
was recent, starting around 9000 years ago, and took place stepwise, possibly up to Medieval times. This complements
a classic phylogeographical interpretation based on the effect of past climate change, and supports the role of
anthropogenic deforestation as a trigger of recent intraspecific differentiation