Aim: We explored the phylogenetic relationships of species of Mesalina, using one nuclear and two mitochondrial loci. This genus of lacertid lizards is widely distributed in North Africa and the ...Middle East and our goal was to develop a scenario capable of explaining the current distribution and evolutionary patterns within the genus in the context of the wider historical biogeography of the region. Location: North Africa and the Middle East. Methods: The assembled dataset consisted of 193 Mesalina individuals, representing 12 species distributed across the geographical range of the genus. Bayesian and maximum likelihood methods were used to support phylogenetic inferences on two mitochondrial (cytochrome b and 16S ribosomal RNA) and one nuclear (beta-fibrinogen intron 7) markers. Palaeogeographical and palaeoclimatic data were used to support the inferred phylogeographical patterns. Results: Mesalina lizards exhibit high genetic diversity and complex phylogenetic patterns, leading to an unsatisfactory systematic hypothesis of one paraphyletic and three polyphyletic traditional species. The estimated divergence times place the origin of the genus in the early Miocene (c. 22 Ma) and the divergence of most currently recognized species in the middle to late Miocene. The inferred ancestral distribution suggests that the genus and most of its species originated somewhere in Arabia or the Middle East, with the exception of the Mesalina olivieri complex, which may be of African origin. Main conclusions: Phylogenetic reconstruction based on the three loci studied suggests a higher than expected cryptic diversity of Mesalina in North Africa and the Middle East. We suggest that the tectonic movements of the Arabian plate, coupled with the climatic changes occurring since the Miocene, may be responsible for the phylogeographical patterns of North African and Middle Eastern Mesalina.
We review the present status in the theoretical and phenomenological understanding of charmonium and bottomonium production in heavy-ion collisions. We start by recapitulating the basic notion of ...“anomalous quarkonium suppression” in heavy-ion collisions and its recent amendments involving regeneration reactions. We then survey in some detail concepts and ingredients needed for a comprehensive approach to utilize heavy quarkonia as a probe of hot and dense matter. The theoretical discussion encompasses recent lattice QCD computations of quarkonium properties in the Quark–Gluon Plasma, their interpretations using effective potential models, inelastic rate calculations and insights from analyses of electromagnetic plasmas. We illustrate the powerful techniques of thermodynamic Green functions (
T
-matrices) to provide a general framework for implementing microscopic properties of heavy quarkonia into a kinetic theory of suppression and regeneration reactions. The theoretical concepts are tested in applications to heavy-ion reactions at SPS, RHIC and LHC. We outline perspectives for future experiments on charmonium and bottomonium production in heavy-ion collisions over a large range of energies (FAIR, RHIC-II and LHC). These are expected to provide key insights into hadronic matter under extreme conditions using quarkonium observables.
Aim: The genetic impact of Quaternary climatic fluctuations on mountain endemic species has rarely been investigated. The Pyrenean rock lizard (Iberolacerta bonnali) is restricted to alpine habitats ...in the Pyrenees where it exhibits a highly fragmented distribution between massifs and between habitats within massifs. Using mitochondrial DNA markers, we set out: (1) to test whether several evolutionary units exist within the species; (2) to understand how the species persisted through the Last Glacial Maximum and whether the current range fragmentation originates from distribution shifts after the Last Glacial Maximum or from more ancient events; and (3) to investigate whether current mitochondrial diversity reflects past population history or current habitat fragmentation. Location: The Pyrenees in south-western France and northern Spain. Methods: We used variation in the hypervariable left domain of the mitochondrial control region of 146 lizards collected in 15 localities, supplemented by cytochrome b sequences downloaded from GenBank to cover most of the species' distribution range. Measures of population genetic diversity were contrasted with population isolation inferred from topography. Classical (F-statistics) and coalescence-based methods were used to assess the level of gene flow and estimate divergence time between populations. We used coalescencebased simulations to test the congruence of our genetic data with a scenario of simultaneous divergence of current populations. Results: Coalescence-based analyses suggested that these peripheral populations diverged simultaneously at the end of the last glacial episode when their habitats became isolated on mountain summits. High mitochondrial diversity was found in peripheral, isolated populations, while the populations from the core of the species' range were genetically impoverished. Where mitochondrial diversity has been retained, populations within the same massif exhibited high levels of genetic differentiation. Main conclusions: As suggested for many other mountain species, the Pyrenean rock lizard survived glacial maxima through short-distance range shifts instead of migration or contraction in distant southern refugia. Most of the main Pyrenean range has apparently been re-colonized from a single or a few source populations, resulting in a loss of genetic diversity in re-colonized areas. As a result, current levels of intra-population mitochondrial diversity are better explained by postglacial population history than by current habitat fragmentation. Genetic population differentiation within massifs implies severe reduction in femalemediated gene flow between patches of habitats.
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► Miocene aridification of Central Asia caused vicariance between Euroasiatic lineages. ► Three lineages involved in the regional diversification in the Western Palearctic. ► The ...African lineage is sister group of the Iberian lineage. ► The European and Caucasian lineages were strongly affected by Pleistocene glaciations.
In most pan-Eurasiatic species complexes, two phenomena have been traditionally considered key processes of their cladogenesis and biogeography. First, it is hypothesized that the origin and development of the Central Asian Deserts generated a biogeographic barrier that fragmented past continuous distributions in Eastern and Western domains. Second, Pleistocene glaciations have been proposed as the main process driving the regional diversification within each of these domains. The European common toad and its closest relatives provide an interesting opportunity to examine the relative contributions of these paleogeographic and paleoclimatic events to the phylogeny and biogeography of a widespread Eurasiatic group. We investigate this issue by applying a multiproxy approach combining information from molecular phylogenies, a multiple correspondence analysis of allozyme data and species distribution models. Our study includes 304 specimens from 164 populations, covering most of the distributional range of the Bufo bufo species complex in the Western Palearctic. The phylogenies (ML and Bayesian analyses) were based on a total of 1988bp of mitochondrial DNA encompassing three genes (tRNAval, 16S and ND1). A dataset with 173 species of the family Bufonidae was assembled to estimate the separation of the two pan-Eurasiatic species complexes of Bufo and to date the main biogeographic events within the Bufo bufo species complex. The allozyme study included sixteen protein systems, corresponding to 21 presumptive loci. Finally, the distribution models were based on maximum entropy. Our distribution models show that Eastern and Western species complexes are greatly isolated by the Central Asian Deserts, and our dating estimates place this divergence during the Middle Miocene, a moment in which different sources of evidence document a major upturn of the aridification rate of Central Asia. This climate-driven process likely separated the Eastern and Western species. At the level of the Western Palearctic, our dating estimates place most of the deepest phylogenetic structure before the Pleistocene, indicating that Pleistocene glaciations did not have a major role in splitting the major lineages. At a shallow level, the glacial dynamics contributed unevenly to the genetic structuring of populations, with a strong influence in the European–Caucasian populations, and a more relaxed effect in the Iberian populations.
This review discusses the clinical applications of magnetic resonance imaging (MRI) for the assessment of neo-adjuvant chemotherapy (NAC) indication, axillary lymph node status, preNAC cancer ...prognosis, early and intermediate response to NAC, and post-NAC residual disease in patients with breast cancer. Contrast-enhanced MRI with analysis of the tumor morphological features and qualitative enhancement kinetics must be considered as the standard method for pre-NAC breast cancer staging and post-NAC residual disease assessment. Diffusion-weighted imaging (DWI) is easy to perform and may increase the specificity of breast MRI for tumor staging, and also for the assessment of tumor multifocality and multicentricity and lymph node status. It also provides an ancillary added value in the early and post-NAC response evaluation. Changes in the functional tumor volume are the main criterion for the early response analysis. Other MRI methods, such as quantitative perfusion analysis, MR spectroscopy and texture analysis, are still under study.
Captive‐bred mallards Anas platyrhynchos have been released for hunting purposes at a very large scale in Europe since the mid‐1970s. In spite of a potential genetic impact, the actual contribution ...of restocked mallards to the genome of the target population has received little attention. The genetic structure of modern wild mallards in the Camargue, Southern France, was assessed from two samples: one originating from shot birds in hunting bags and one from presumed wild ducks captured alive in a hunting‐free reserve. Reference samples originated from five mallard farms, as well as from museum samples collected before the mid‐1970s (i.e. before massive mallard releases started). Our results revealed that the genetic signature of wild wintering mallards has not changed significantly because museum and presumed wild samples from the Camargue hunting‐free nature reserve were genetically similar, and clearly differentiated from the farm mallards. This suggests that mallard releases in the Camargue or elsewhere in France, although massive, have not actually translated into complete admixture of wild and captive genomes, most likely due to low survival of released birds once in the wild. Nevertheless, although genetic introgression of the wild population by captive‐bred was contained, we found significant rates of hybridization between wild and captive‐bred mallards in modern samples. This result suggests that long‐term releases of captive‐bred mallards, if carried on at such large scale, could compromise irreversibly the genetic structure and composition of European mallards. This work contributes to fill in the gap on the monitoring of the genetic consequences of large‐scale game releases for exploitation.
Selection on allozymes has sometimes been advanced as one explanation for the low levels of population differentiation detected in avian populations by the use of enzymatic markers. Comparisons of ...the amount of population subdivision (estimated by FST values or analogous indices) measured by enzymatic and mitochondrial DNA (mtDNA) markers in birds were seen as evidence for this because mtDNA typically produces a more structured picture of population subdivisions. In fact, when taking into account the smaller effective population size of mtDNA, nuclear and mitochondrial markers give concordant results. Some discrepancies still exist, but I suggest that some might originate from different amounts of nuclear vs. mitochondrial gene flow due to partial reproductive isolation. Variable number of tandem repeat (VNTR) loci do not provide a dramatically different picture of population structures in birds compared to allozymes. Although more tests are needed, such as comparing the amount of genetic structure detected in the same populations with allozymes and microsatellites, the low levels of population subdivision measured with allozymes in birds seem to reflect historical and demographic processes and would not appear to result from any peculiarities of bird enzymatic loci.
Recent genetic studies have shown that introgression rates among loci may greatly vary according to their location in the genome. In particular, several cases of mito-nuclear discordances have been ...reported for a wide range of organisms. In the present study, we examine the causes of discordance between mitochondrial (mtDNA) and nuclear DNA introgression detected in North American populations of the Great Black-backed Gull (Larus marinus), a Holarctic species, from the Nearctic North American Herring Gull (Larus smithsonianus). Our results show that extensive unidirectional mtDNA introgression from Larus smithsonianus into Larus marinus in North America cannot be explained by ancestral polymorphism but most likely results from ancient hybridization events occurring when Larus marinus invaded the North America. Conversely, our nuclear DNA results based on 12 microsatellites detected very little introgression from Larus smithsonianus into North American Larus marinus. We discuss these results in the framework of demographic and selective mechanisms that have been postulated to explain mito-nuclear discrepancies. We were unable to demonstrate selection as the main cause of mito-nuclear introgression discordance but cannot dismiss the possible role of selection in the observed pattern. Among demographic explanations, only drift in small populations and bias in mate choice in an invasive context may explain our results. As it is often difficult to demonstrate that selection may be the main factor driving the introgression of mitochondrial DNA in natural populations, we advocate that evaluating alternative demographic neutral hypotheses may help to indirectly support or reject hypotheses invoking selective processes.
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