881 resultados para Blue shark, Mediterranean phylogeography demography, mtDNA
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Combining nuclear (nuDNA) and mitochondrial DNA (mtDNA) markers has improved the power of molecular data to test phylogenetic and phylogeographic hypotheses and has highlighted the limitations of studies using only mtDNA markers. In fact, in the past decade, many conflicting geographic patterns between mitochondrial and nuclear genetic markers have been identified (i.e. mito-nuclear discordance). Our goals in this synthesis are to: (i) review known cases of mito-nuclear discordance in animal systems, (ii) to summarize the biogeographic patterns in each instance and (iii) to identify common drivers of discordance in various groups. In total, we identified 126 cases in animal systems with strong evidence of discordance between the biogeographic patterns obtained from mitochondrial DNA and those observed in the nuclear genome. In most cases, these patterns are attributed to adaptive introgression of mtDNA, demographic disparities and sex-biased asymmetries, with some studies also implicating hybrid zone movement, human introductions and Wolbachia infection in insects. We also discuss situations where divergent mtDNA clades seem to have arisen in the absence of geographic isolation. For those cases where foreign mtDNA haplotypes are found deep within the range of a second taxon, data suggest that those mtDNA haplotypes are more likely to be at a high frequency and are commonly driven by sex-biased asymmetries and/or adaptive introgression. In addition, we discuss the problems with inferring the processes causing discordance from biogeographic patterns that are common in many studies. In many cases, authors presented more than one explanation for discordant patterns in a given system, which indicates that likely more data are required. Ideally, to resolve this issue, we see important future work shifting focus from documenting the prevalence of mito-nuclear discordance towards testing hypotheses regarding the drivers of discordance. Indeed, there is great potential for certain cases of mitochondrial introgression to become important natural systems within which to test the effect of different mitochondrial genotypes on whole-animal phenotypes.
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Résumé Les changements climatiques du Quaternaire ont eu une influence majeure sur la distribution et l'évolution des biota septentrionaux. Les Alpes offrent un cadre spatio-temporel bien étudié pour comprendre la réactivité de la flore et le potentiel d'adaptation d'une espèce végétale face aux changements climatiques. Certaines hypothèses postulent une diversification des espèces en raison de la disparition complète de la flore des Alpes et d'un isolement important des espèces dans des refuges méridionaux durant les dernières glaciations (Tabula Rasa). Une autre hypothèse stipule le maintien de poches de résistance pour la végétation au coeur des Alpes (Nunataks). Comme de nombreuses espèces végétales présentant un grand succès écologique semblent avoir réagi aux glaciations par la multiplication de leur génome (autopolyploïdie), leur étude en milieu naturel devrait permettre de comprendre les avantages inhérents à la polyploïdie. Biscutella laevigata est un modèle emblématique de biogéographie historique, diverses études ayant montré que des populations diploïdes sont actuellement isolées dans les zones restées déglacées durant le dernier maximum glaciaire, alors que des tétraploïdes ont recolonisé l'ensemble des zones alpines mises à nu par le retrait des glaciers. Si le contexte périglaciaire semble avoir favorisé ce jeune complexe autopolyploïde, les circonstances et les avantages de cette mutation génomique ne sont pas encore clairs. Y a-t-il eu de multiples événements de polyploïdisation ? Dans quelle mesure affecte(nt)il(s) la diversité génétique et le potentiel évolutif des polyploïdes ? Les polyploïdes ont-ils une grande flexibilité génomique, favorisant une radiation adaptative, ou doivent-ils leur succès à une grande plasticité écologique ? Cette étude aborde ces questions à différentes échelles spatiales et temporelles. L'échelle régionale des Alpes occidentales permet d'aborder les facteurs distaux (aspects historiques), alors que l'échelle locale cherche à appréhender les facteurs proximaux (mécanismes évolutifs). Dans les Alpes occidentales, des populations ont été densément échantillonnées et étudiées grâce à (1) leur cytotype, (2) leur appartenance taxonomique, (3) leur habitat et (4) des marqueurs moléculaires de l'ADN chloroplastique, en vue d'établir leurs affinités évolutives. Á l'échelle locale, deux systèmes de population ont été étudiés : l'un où les populations persistent en périphérie de l'aire de distribution et l'autre au niveau du front actif de colonisation, en marge altitudinale. Les résultats à l'échelle des Alpes occidentales révèlent les sites d'intérêt (refuges glaciaires, principales barrières et voies de recolonisation) pour une espèce représentative des pelouses alpines, ainsi que pour la biodiversité régionale. Les Préalpes ont joué un rôle important dans le maintien de populations à proximité immédiate des Alpes centrales et dans l'évolution du taxon, voire de la végétation. Il est aussi démontré que l'époque glaciaire a favorisé l'autopolyploïdie polytopique et la recolonisation des Alpes occidentales par des lignées distinctes qui s'hybrident au centre des Alpes, influençant fortement leur diversité génétique et leur potentiel évolutif. L'analyse de populations locales en situations contrastées à l'aide de marqueurs AFLP montre qu'au sein d'une lignée présentant une grande expansion, la diversité génétique est façonnée par des forces évolutives différentes selon le contexte écologique et historique. Les populations persistant présentent une dispersion des gènes restreinte, engendrant une diversité génétique assez faible, mais semblent adaptées aux conditions locales de l'environnement. À l'inverse, les populations colonisant la marge altitudinale sont influencées par les effets de fondation conjugués à une importante dispersion des gènes et, si ces processus impliquent une grande diversité génétique, ils engendrent une répartition aléatoire des génotypes dans l'environnement. Les autopolyploïdes apparaissent ainsi comme capables de persister face aux changements climatiques grâce à certaines facultés d'adaptation locale et de grandes capacités à maintenir une importante diversité génétique lors de la recolonisation post-glaciaire. Summary The extreme climate changes of the Quaternary have had a major influence on species distribution and evolution. The European Alps offer a great framework to investigate flora reactivity and the adaptive potential of species under changing climate. Some hypotheses postulate diversification due to vegetation removal and important isolation in southern refugia (Tabula Rasa), while others explain phylogeographic patterns by the survival of species in favourable Nunataks within the Alps. Since numerous species have successfully reacted to past climate changes by genome multiplication (autopolyploidy), studies of such taxa in natural conditions is likely to explain the ecological success and the advantages of autopolyploidy. Early cytogeographical surveys of Biscutella laevigata have shed light on the links between autopolyploidy and glaciations by indicating that diploids are now spatially isolated in never-glaciated areas, while autotetraploids have recolonised the zones covered by glaciers- during the last glacial maximum. A periglacial context apparently favoured this young autopolyploid complex but the circumstances and the advantages of this genomic mutation remain unclear. What is the glacial history of the B. laevigata autopolyploid complex? Are there multiple events of polyploidisation? To what extent do they affect the genetic diversity and the evolutionary potential of polyploids? Is recolonisation associated with adaptive processes? How does long-term persistence affect genetic diversity? The present study addresses these questions at different spatiotemporal scales. A regional survey at the Western Alps-scale tackles distal factors (evolutionary history), while local-scale studies explore proximal factors (evolutionary mechanisms). In the Western Alps, populations have been densely sampled and studied from the (1) cytotypic, (2) morphotaxonomic, (3) habitat point of views, as well as (4) plastid DNA molecular markers, in order to infer their relationships and establish the maternal lineages phylogeography. At the local scale, populations persisting at the rear edge and populations recolonising the attitudinal margin at the leading edge have been studied by AFLPs to show how genetic diversity is shaped by different evolutionary forces across the species range. The results at the regional scale document the glacial history of a widespread species, representative of alpine meadows, in a regional area of main interest (glacial refugia, main barriers and recolonisation routes) and points out to sites of interest for regional biodiversity. The external Alps have played a major role in the maintenance of populations near the central Alps during the Last Glacial Maximum and influenced the evolution of the species, and of vegetation. Polytopic autopolyploidy in different biogeographic districts is also demonstrated. The species has had an important and rapid radiation because recolonisation took place from different refugia. The subsequent recolonisation of the Western Alps was achieved by independent lineages that are presently admixing in the central Alps. The role of the Pennic summit line is underlined as a great barrier that was permeable only through certain favourable high-altitude passes. The central Alps are thus viewed as an important crossroad where genomes with different evolutionary histories are meeting and admixing. The AFLP analysis and comparison of local populations growing in contrasted ecological and historical situations indicate that populations persisting in the external Alps present restricted gene dispersal and low genetic diversity but seem in equilibrium with their environment. On the contrary, populations colonising the attitudinal margin are mainly influenced by founder effects together with great gene dispersal and genotypes have a nearly random distribution, suggesting that recolonisation is not associated with adaptive processes. Autopolyploids that locally persist against climate changes thus seem to present adaptive ability, while those that actively recolonise the Alps are successful because of their great capacity to maintain a high genetic diversity against founder effects during recolonisation.
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We date turning points of the reference cycle for 19 Mediterranean countries andanalyze their structure and interdependences. Fluctuations are volatile and not highlycorrelated across countries; recessions are deep but asynchronous making average outputlosses in the area limited. Heterogeneities across countries and regions are substantial.Mediterranean cycles are time varying but their evolution is not linked withthe Euro-Mediterranean partnership process. The concordance of cyclical fluctuationsis poorly related to trade and financial linkages and to their evolution over time.
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Audit report on the City of Blue Grass, Iowa for the year ended June 30, 2007
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A macromorphological study is made on taxa of the genusOrnithogalum subg.Heliocharmos in North Africa, Spain, and France. The results obtained are consistent with data from cytogenetics, reproductive biology and strategies of reproduction. They allow the retention of two species:O. algeriense and O. umbellatum. A biogeographical and phylogenetic interpretation of the subgenus is proposed for the western Mediterranean. Theoretical views on phenetics are discussed.
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We investigate macroeconomic fluctuations in the Mediterranean basin, their similarities and convergence. A model with four indicators, roughly covering theWest, the East and the Middle East and the North Africa portions of theMediterranean, characterizes well the historical experience since the early 1980.Idiosyncratic causes still dominate domestic cyclical fluctuations in many countries. Convergence and divergence coexist are local and transitory. The cyclicaloutlook for the next few years is rosier for the East than for the West.
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Is surgery for primary hyperparathyroidism easier when methylene blue (MB) is given preoperatively? This retrospective study compares the durations of interventions for primary hyperparathyroidism carried out after i.v. MB administration to those when no MB was given. Over a period of 20 years (June 1976 to December 1996), 175 consecutive patients (56 men and 119 women, with ages ranging from 16 to 92, mean 59.6) were operated upon for primary hyperparathyrodism; 55 were operated before February 1986--the period when BM was introduced routinely, and 120 after. Thirty-two other patients were excluded from the study: 14 had had a previous cervicotomy and 18 another procedure in addition to the parathyroidectomy (usually on the thyroid gland), two conditions which prolonged the time devoted to parathyroid identification and excision. Preoperative calcemia averaged 2.97 mmol/L (2.34 to 4.59) and mean preoperative PTH was equal to 2.6 times the upper normal limit (0.5 to 24.1). Both groups were similar for as age, sex, preoperative calcium and PTH, and histologies. Methylene blue was administered intravenously (5 mg/kg diluted in 500 cc of 5% glucose) over a period of time of one hour starting two hours prior to surgery. All 175 procedures were performed by two surgeons and duration of surgery was recorded from the anesthesiologist's notes. There were 149 adenomas (85%), 24 hyperplasias (14%), a combination of both in two, and unspecified in two others. Except for a case of acute lower back pain synchronous to the injection of the dye (which was immediately stopped), MB was well tolerated. Mean duration for the 55 interventions performed without MB was 68 minutes (35 to 140, median 60), compared to 49 minutes for the 120 procedures carried out after MB had been given (20 to 155, median 45). Differences in operative, times were highly significant (p < 10(-6) and represented a gain of time of 27%. Surgery for primary hyperparathyroidism was significantly shorter when it was preceded by the administration of MB, a dye which facilitates the identification of pathologic parathyroid gland(s).
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Whether or not species participating in specialized and obligate interactions display similar and simultaneous demographic variations at the intraspecific level remains an open question in phylogeography. In the present study, we used the mutualistic nursery pollination occurring between the European globeflower Trollius europaeus and its specialized pollinators in the genus Chiastocheta as a case study. Explicitly, we investigated if the phylogeographies of the pollinating flies are significantly different from the expectation under a scenario of plant-insect congruence. Based on a large-scale sampling, we first used mitochondrial data to infer the phylogeographical histories of each fly species. Then, we defined phylogeographical scenarios of congruence with the plant history, and used maximum likelihood and Bayesian approaches to test for plant-insect phylogeographical congruence for the three Chiastocheta species. We show that the phylogeographical histories of the three fly species differ. Only Chiastocheta lophota and Chiastocheta dentifera display strong spatial genetic structures, which do not appear to be statistically different from those expected under scenarios of phylogeographical congruence with the plant. The results of the present study indicate that the fly species responded in independent and different ways to shared evolutionary forces, displaying varying levels of congruence with the plant genetic structure
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Exon-primed intron-crossing (EPIC) markers as a tool for ant phylogeography. Due to their local abundance, diversity of adaptations and worldwide distribution, ants are a classic example of adaptive radiation. Despite this evolutionary and ecological importance, phylogeographical studies on ants have relied largely on mitochondrial markers. In this study we design and test exon-primed intron-crossing (EPIC) markers, which can be widely used to uncover ant intraspecific variation. Candidate markers were obtained through screening the available ant genomes for unlinked conserved exonic regions interspersed with introns. A subset of 15 markers was tested in vitro and showed successful amplification in several phylogenetically distant ant species. These markers represent an important step forward in ant phylogeography and population genetics, allowing for more extensive characterization of variation in ant nuclear DNA without the need to develop species-specific markers.
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In order to evaluate the success of the reintroduction of the Eurasian otter (Lutra lutra) in the Empordh wetlands (Parc Natural dels Aiguamolls de I'Empordhà), and the Muga and Fluvih basins, density of fish, biomass and production in the Muga and Fluvia Rivers have been estimated, since fishes represent the principal prey in the otter diet. 12 study sites were selected in order to survey the main flows in both basins. Electrofishing surveys were conducted by blocking off the station with barrier nets, which was performed upon 3 successive catches. The density estimated presents a range of 1,136-1 25 ind .ha' in the Muga basin, 4,49-163 ind.ha' in the Fluvih basin and 3,76-52,2 ind.ha' in the Empordh wetlands. Estimated biomass ranges are 0,616-277,6 g.m2, 8,79-351,2 g.m2, and 5,7-108 g.m-2 respectively. These density anfi biomass ranges are similar to other results obtained from rivers inhabited by the Eurasian otter in NE Spain
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With an approach, based on chromosomal, biochemical and morphological analysis, we show that the animals wich are classically attributed to C. r. gueldenstaedti and/or to C. r. monacha belong in fact to the taxon C. suaveolens. The oriental forms, formely seen as C. russula, are of the same karyotype as C. suaveolens and are biochemically close to C. suaveolens in Central Europe. The origin of the taxonomical confusion might stem from the large morphological variation in and between populations of C. suaveolens in the Near East. Based on our results C. russula monacha Thomas, 1906 belongs to the polymorphic species C. suaveolens Pallas, 1811 and we propose to consider C. (russula) gueldenstaedti Pallas, 1881 as "incertae sedis".
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Dolphinfish (Coryphaena hippurus) is an epipelagic, highly migratory species distributed worldwide in tropical and temperate waters including the Mediterranean Sea. Protein electrophoresis analyses can provide knowledge of the genetic population structure of the species and therefore be used as a tool for fishery management. Areas sampled include the islands of Majorca and Sicily in the western Mediterranean and the Canary Islands in the eastern Atlantic. The results of the protein electrophoresis reveal a level of genetic variability similar to other highly migratory species. No differences were found among locations, and it was not possible to reject the null hypothesis of one panmictic population in the area studied
Lipid reserves of red mullet (Mullus barbatus) during pre-spawning in the northwestern Mediterranean
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Lipid reserves are a particularly important attribute of fishes because they have a large influence on growth, reproduction and survival. This study analyses the lipid content of red mullet (Mullus barbatus) pre-spawners in three different areas of the northwestern Mediterranean in relation to trawling activities and river runoff. The muscle lipid was considered as an indicator of the somatic condition of individuals whilst the gonad lipid was used as a proxy of the energy invested in reproduction. The results show that fish with the highest muscle lipid levels inhabited the area where fishing impact was lowest. Since the abundance and biomass of polychaetes, which represent the main food source for red mullet, were found to be lower in trawled zones than in unfished ones, we suggest that differences in the muscle lipid levels between areas might be attributed to variation in prey abundance in relation to fishing impact. However, no impact of river runoff on lipid reserves of red mullet was observed. The results also show that muscle and gonad lipid reserves are not related to each other during pre-spawning