Добірка наукової літератури з теми "Atlantic - Mediterranean suture zone"

In this study, all samples from Tortonian to Early Pliocene sediments of Zvernec-Vlora and Kavaja-Durres regions within Peri-Adriatic Foredeep (PAF) of Albania containing Globorotalia acostaensis were studied qualitatively and quantitatively. Based on these analyses resulted that G. acostaensis have changed coiling ratio direction during G. acostaensis and G. obliquus extremus Zone of Tortonian, differently from that known in Mediterranean area up to now. This is not a short time interval, which more exactly is from the first appearance of G. acostaensis to first appearance of G. suterae, at the upper part of G. extremus Zone. Another documented and explaining unconformity here is related with beginning of Pliocene sediments. There are at least four alienating sinistral and dextral coiling changes in G.acostaensis populations. Also in this work is given the history of the study of G acostaensis and which maybe causes that this species in Mediterranean province and especially in our country is used relatively late as zonal marker species. The main object of stratigraphers and paleontologists has been finding a successive section, with uninterrupted sedimentation, possibly for the longest geological time. Regarding to this phenomenon could be explained resulting unconformity between coiling ratio changes in Globorotalia acostaensis of the present study and other studies carried out in Mediterranean area on this occasion up to now. It is difficult to understand here the resulting unconformity during the main part of Tortonian age, which prolonged more than 2 m.y. Another resulting unconformity discovered at the Miocene/Pliocene boundary of the Kavaja-Durres regions is very significant. In these regions was discovered an earlier Pliocene sedimentation than known up to now according to resulting alternations of coiling direction of Globorotalia acostaensis prior to Pliocene Sphaeroidinellopsis Acme zone. These data are in favour of those based on the isotopie stratigraphy, which give a new definition at 5.32 M.Y. Miocene/Pliocene boundary instead of 5.1 or 5.2 M.Y. given previously based on absolute age. Coiling changes, in our case that of G. acostaensis are in response to changing climates or alternation of different cold and warm water populations resulting from changes in the boundaries between water masses as at the beginning of the Pliocene when the water masses of the Atlantic Ocean overflowed the Mediterranean area. Here is also proposed to correct the Neogene paleoclimatic curve referring, for the interval of G. acostaensis range distribution.

The Tell-Rif (Tell in Algeria and Tunisia; Rif in Morocco) is the orogenic system fringing to the south the West Mediterranean basins. This system comprises three major tectonic-palaeogeographic zones from north to south: (1) the internal zones (AlKaPeCa for Alboran, Kabylies, Peloritan, Calabria) originating from the former northern European margin of the Maghrebian Tethys, (2) the “Flyschs zone” regarded as the former cover of the oceanic domain and (3) the external zones, forming the former southern Maghrebian Tethys margin more or less inverted. The Tell-Rif is interpreted as the direct result of the progressive closure of the Maghrebian Tethys until the collision between AlKaPeCa and Africa and, subsequently, the propagation of the deformation within Africa. This gives a consistent explanation for the offshore Neogene geodynamics and most authors share this simple scenario. Nevertheless, the current geodynamic models do not completely integrate the Tell-Rif geology. Based on the analysis of surface and sub-surface data, we propose a reappraisal of its present-day geometry in terms of geodynamic evolution. We highlight its non-cylindrical nature resulting from both the Mesozoic inheritance and the conditions of the tectonic inversion. During the Early Jurassic, we emphasize the development of NE-SW basins preceding the establishment of an E-W transform corridor connecting the Central Atlantic Ocean with the Ligurian Tethys. The Maghrebian Tethys developed just after, as the result of the Late Jurassic-Early Cretaceous left-lateral spreading between Africa and Iberia. By the Late Cretaceous, the occurrence of several tectonic events is related to the progressive convergence convergence between the two continents. A major pre-Oligocene (pre-35 Ma) compressional event is recorded in the Tell-Rif system. The existence of HP-LT metamorphic rocks associated with fragments of mantle in the External Metamorphic Massifs of the Eastern Rif and Western Tell shows that, at that time, the western part of the North-African margin was involved in a subduction below a deep basin belonging to the Maghrebian Tethys. At the same time, the closure of the West Ligurian Tethys through east-verging subduction led to a shift of the subduction, which jumped to the other side of AlKaPeCa involving both East Ligurian and Maghrebian Tethys. Slab rollback led to the development of the Oligo-Miocene back-arc basins of the West-Mediterranean, reworking the previous West Ligurian Tethys suture. The docking of AlKaPeCa against Africa occurred during the Late Burdigalian (17 Ma). Subsequently, the slab tearing triggered westward and eastward lateral movements that are responsible for the formation of the Gibraltar and Tyrrhenian Arcs respectively. The exhumation of the External Metamorphic Massifs occurred through tectonic underplating during the westward translation of the Alboran Domain. It resulted in the formation of both foredeep and wedge-top basins younger and younger westward. The lack of these elements in the eastern part of the systems signs a different evolution dominated by frontal accretion. In the discussion, we precisely address the origin of the non-cylindrical behavior of the orogenic system and question the mechanisms explaining at large scale the phases of coupling/uncoupling between the major plates.

We document the distribution of the common toadBufo bufoand the spined toadB. spinosusat their contact zone across France with data from a mitochondrial DNA RFLP assay, complementing similar work including nuclear markers in the northwest and southeast of France and in Italy. We also reconstruct geographical clines across the species’ contact zone in central France.Bufo bufois found in the north-eastern half of France.Bufo spinosusis found in the south-western complement. The contact zone they form runs from the Atlantic coast near Caen, France, to the Mediterranean coast near Savona, Italy, and has a length of over 900 km. In central FranceB. bufoandB. spinosusengage in a hybrid zone with a unimodal genetic signature. Hybrid zone width is ca. 10 km at mitochondrial DNA and averages at 61 km for four nuclear loci. The hybrid zone is distinctly asymmetric with a signature ofB. spinosusinB. bufoand not the other way round. We attribute this observation toB. bufomoving southwards at the expense ofB. spinosus, with introgression in the direction of the advancing species. We noted substantial geographic variation in characters for species identification. Morphological species identification performs well in France, but breaks down in Italy. Mitochondrial DNA is inconclusive in south-eastern France and Italy. The nuclear genetic markers perform consistently well but have not yet been applied to the zone in full. Possible, but surely heterogeneous ecological correlates for the position of the hybrid zone are mountains and rivers.

The Atlantic–Mediterranean transition zone between the Alborán Sea and the Gulf of Cádiz constitutes the most prominent marine geographic barrier in European waters and includes known phylogeographic breaks such as the Strait of Gibraltar and the Almería-Oran Front. A genetic shift in this area has been previously documented for the European littoral shrimp Palaemon elegans. Here we carried out a phylogeographic analysis with the congeneric and sympatric species Palaemon serratus to test for similar intraspecific genetic differentiation and geographic structure. This littoral prawn is distributed in the Northeastern Atlantic Ocean, the Mediterranean Sea and the Black Sea. We compared DNA sequences from the mitochondrial genes Cox1 and to a lesser extent from 16S rRNA of several Atlantic and Mediterranean populations. Furthermore, sequences from the nuclear gene Enolase were included for corroborating differences between Mediterranean and Atlantic individuals. A pronounced genetic differentiation was detected between the Mediterranean and Atlantic populations, amounting to 10.14% in Cox1 and 2.0% in 16S, indicating the occurrence of two independent evolutionary lineages. Interestingly, specimens from the Atlantic Gulf of Cadiz cluster together with the Mediterranean individuals, indicating that a biogeographic barrier appears to be located west of the Strait of Gibraltar.

The anglerfish species Lophius piscatorius and Lophius budegassa are among the most valuable fishes sought after by bottom fisheries in western and southern European waters. It is currently believed that there are two stocks for each of the two species, north and south, which determine their assessment and management. A genetic analysis using eight polymorphic microsatellite markers was carried out on samples collected from western European waters and the south-western Mediterranean Sea. The results strongly suggest that the boundary between northern and southern stocks is not genetically supported. However, populations were not genetically homogeneous. Besides a pattern of genetic differentiation between Mediterranean and the rest of the samples, the L. budegassa samples taken from the Spain Atlantic zone and from the Portugal Atlantic zone were genetically distinct, whereas the samples taken in the French Atlantic zone for the L. piscatorius species seem to be different from the rest of the samples under study. This can be indicative of a more subtle genetic structure that deserves more study for guaranteeing adequate fishery management of these species.

The comparison of shells of Brachystomia carrozzai (van Aartsen, 1987) of Atlantic and Mediterranean origin allowed us to detect slight but constant morphological differences. In particular, Mediterranean specimens, here attributed to Brachystomia pizzinii n. sp., show, with respect to B. carrozzai, a more protruding and widely umbilicated protoconch, and a teleoconch with more convex whorls and clear suture. A further species with distribution limited to the waters of southern Spain, in the literature attributed to B. carrozzai as well, is described here as Brachystomia hispanica n. sp. The latter is distinguished from both B. carrozzai and B. pizzinii due to its small size and broader profile. Further, Brachystomia sorianoi (Peñas & Rolán, 2006) is reported for the first time from the Bay of Algeciras.

The MARCOS cruise, which took place in the South Central Mediterranean Sea on board the RV ‘Urania’, resulted in the collection of 27 species of Echinodermata from shallow to bathyal depths, many from around Malta (the Fisheries Management Zone). The fauna is represented by common to rare taxa already reported from the Mediterranean with the exception of the amphi-Atlantic ophiuroid Ophiotreta valenciennesi rufescens (Koehler, 1896), recorded from the Mediterranean Basin for the first time. Odontaster mediterraneus (von Marenzeller, 1893) and Luidia sarsi Lutken, 1858 are also first records for the Maltese Islands.

We identify long transform faults that frame the eastern Mediterranean Sea and that were active during Jurassic and probably the Early Cretaceous, during the opening of the central Atlantic Ocean. We show that the African margin of the eastern Mediterranean Sea is an 1800 km long transform fault that absorbed the Africa/Eurasia Jurassic left-lateral motion during the opening of the central Atlantic. We call this transform fault the Eastern Mediterranean South Transform fault (EMST). We identify two other transform faults that were active simultaneously and framed the eastern Mediterranean Sea during its formation. These are the Apulia Transform fault (AT) and the Eastern Mediterranean North Transform fault (EMNT). The AT, three hundred km north of the EMST, followed the southern boundary of the Apulia block. Still 300 km farther north, the EMNT formed the northern boundary of this eastern Mediterranean shear zone. This last fault has been destroyed over a large portion by the Hellenic subduction. We relate these transform faults to the kinematics of the Jurassic Africa/Eurasia motion. We conclude that the eastern Mediterranean Sea is a long pull-apart created by left-lateral shearing of the Adria block as it was structurally linked to Africa.

The myrionematoid brown alga Ulonema rhizophorum Foslie (Phaeophyceae, Chordariaceae) is reported for the first time from the Mediterranean Sea. This species was collected growing as an epiphyte on Ulva sp. from the Dardanelles (Sea of Marmara, Turkey) in the midlittoral zone. Ulonema rhizophorum is characterized by downwardly produced rhizoids from the basal system. A key to the Mediterranean related genera of Ulonema is provided.

La spéciation est le processus évolutif au cours duquel une espèce se scinde en deux lignées qui divergent en accumulant des barrières reproductives, jusqu'à l’acquisition d’un isolement reproductif total. Durant ce processus, les lignées divergentes peuvent toujours s’échanger des gènes par hybridation, mais le flux génique est progressivement limité par l’accumulation des barrières. Il en résulte une semi-perméabilité des génomes, où certains locus s’échangent librement entre lignées et restent indifférenciés tandis que d’autres n’introgressent pas, contribuant ainsi à l’établissement de régions génomiques divergentes, appelées îlots génomiques de spéciation. L'étude de l’établissement, l’accumulation, l’érosion et la maintenance de ces barrières et de leurs effets sur la semiperméabilité des génomes de lignées en cours de spéciation permet de comprendre comment de nouvelles espèces se forment. L'avènement des techniques de séquençage à haut débit a permis de caractériser le paysage génomique de divergence chez de multiples lignées en cours de spéciation à travers l’arbre du vivant. Ces études ont permis de mesurer l’influence de l’histoire démographique et de l’architecture génomique comme déterminants majeurs du paysage génomique de divergence. Toutefois, d'autres facteurs pourraient intervenir et expliquer la diversité des trajectoires évolutives pouvant conduire ou non à la spéciation. Le principal objectif de cette thèse est d'évaluer l'impact des traits d'histoire de vie des espèces sur la spéciation. Nous avons choisi d’étudier 20 espèces de poissons marins subdivisées en deux lignées (Atlantique et Méditerranéenne), et présentant une large diversité de niveaux de divergence et de traits d’histoire de vie. Dans le premier chapitre, nous avons étudié les déterminants de la diversité génétique, substrat sur lequel s’établit la divergence lors de la séparation initiale des lignées. Nous avons observé que la longévité adulte des po issons marins est corrélée négativement à la diversité génétique, et nous avons démontré que cette relation pouvait s’expliquer par une plus grande variance du succès reproducteur chez les espèces longévives à cause de stratégies reproductives particulières aux poissons marins (forte mortalité juvénile, faible mortalité adulte et augmentation de la fécondité avec l’âge). Puis, dans un second chapitre, nous avons détecté une grande diversité d’histoires évolutives entre espèces, caractérisée par un fort gradient de divergence génétique entre lignées atlantiques et méditerranéennes. Ce gradient reflète en partie le niveau de semi-perméabilité des génomes. Les espèces à faible différentiation présentent un isolement reproductif faible, alors que les espèces les plus fortement différenciées montrent un isolement reproductif quasi-complet. Les traits d’histoire de vie des espèces expliquent en partie cette diversité de niveaux d’isolement via différents mécanismes. La durée de vie larvai re influence négativement la différenciation génétique en modulant les capacités de dispersion, l’effet de la taille du corps indique un effet négatif de l’abondance long-terme sur la divergence, et la longévité semble impacter le nombre de générations écoulées depuis la séparation ancestrale. En conclusion, les 20 espèces étudiées présentent une variabilité surprenante d’histoires évolutives au regard des similitudes de leur histoire biogéographique et leur architecture génomique. Les relations entre traits d’histoire de vie et histoire évolutive des espèces sont complexes, mais nous avons pu éclairer certaines d’entre elles en décomposant l’implication des traits dans les différentes étapes de la spéciation. L’application de l’approche de génomique comparative développée au cours de cette thèse dans d’autres zones de suture permettra d’étendre nos connaissances des déterminants du tempo et du mode de la spéciation
Speciation is the evolutionary process through which a species splits into two lineages that diverge and accumulate reproductive barriers, until complete reproductive isolation is achieved. During this process, the diverging lineages can still exchange genes by hybridisation, but gene flow is progressively restricted by the accumulation of barriers. This results in semi-permeable genomes, whereby some loci exchange freely between lineages and remain undifferentiated while others do not introgress, thus contributing to the establishment of divergent genomic regions, called genomic islands of speciation. The study of the establishment, accumulation, erosion and maintenance of these barriers and their effects on the semipermeability of the genomes of lineages undergoing speciation helps to understand how new species are formed. The advent of high-throughput sequencing techniques has made it possible to characterise the genomic landscape of divergence in multiple lineages undergoing speciation across the tree of life. These studies have shown the influence of the demographic history and genomic architecture as major determinants of the genomic landscape of divergence. However, other factors could intervene and explain the diversity of evolutionary trajectories that may or may not lead to speciation. The main objective of this thesis is to assess the impact of species' life history traits on speciation. We have chosen to study 20 marine fish species subdivided into two lineages (Atlantic and Mediterranean), and presenting a wide diversity of degrees of divergence and life history traits. These traits are thought to impact on the intensity of genetic drift, dispersal abilities and generation time of the species. In the first chapter, we studied the determinants of genetic diversity, the substrate on which divergence is built during the initial separation of lineages. We observed that adult longevity of marine fishes is negatively correlated w ith genetic diversity, and we demonstrated that this relationship could be explained by a greater variance in reproductive success in long-lived species due to reproductive strategies specific to marine fishes (high juvenile mortality, low adult mortality and increased fecundity with age). Then, in a second chapter, we discovered a great diversity of evolutionary histories between species, characterised by a strong gradient of genetic divergence between Atlantic and Mediterranean lineages. This gradient partly reflects the level of semi-permeability of the genomes. Species with low differentiation show low reproductive isolation, whereas the most highly differentiated species show almost complete reproductive isolation. Species' life history traits partly explain this diversity in isolation levels via different mechanisms. Larval duration negatively influences genetic differentiation by modulating dispersal capacities, the effect of body size indicates a negative effect of long-term abundance on divergence, while longevity seems to impact the number of generations elapsed since ancestral separation. In conclusion, the 20 species studied show a surprising variability of evolutionary histories considering the similarities of their biogeographic history and genomic architecture. The relationships between life-history traits and the evolutionary history of the species proved to be complex, but we were nevertheless able to shed light on some of them by decomposing the involvement of traits in the different stages of speciation. The application of the comparative genomics approach developed in this thesis to other suture zones will further extend our knowledge of the determinants of the tempo and mode of speciation

In this chapter, we look at four cases: Genoa, Venice, Portugal, and the Netherlands. Genoa, Venice, and Portugal acted as transitional agents over a five- to six-hundred-year period, creating sea power and trading regimes to move Asian commodities and innovations to and from European markets. While Genoa and Venice were primarily Mediterranean-centric, Portugal led the breakthrough from the constraints of the inland sea and inaugurated Europe’s Atlantic focus. None of these actors possessed the power of China nor subsequent global actors, but for their age, they were critical technological leaders, providing a technological bridge from the eastern zone of Eurasia to the western zone. The Netherlands fits into this narrative by combining Baltic and Atlantic activities to construct a European trade regime that greatly overshadowed the earlier transitional efforts. Buttressed by the development of agrarian and industrial technology and a heavy reliance on peat and wind as energy sources, the Dutch case seems idiosyncratic. Most critically, its energy transition was only partial. Although the Netherlands made clear advances in some power-driven machinery and technological innovation , the heat and energy that were expended remained constrained by the inherent limitations of the energy sources.

By examining both contemporary processes and long-term records of change, this volume explores the climates, landscapes, ecosystems, and hazards that comprise the Mediterranean world. This is the only region on Earth where three continents meet and their interaction has produced a very distinctive physical geography. This book examines the landscapes and processes at the margins of the three continents and the distinctive marine environment between them. In broad terms, the physical geography of the Mediterranean is a product of long-term interplay between tectonic forces, climate change, river basin and marine processes, and biosphere dynamics, as well as the action of humans during the course of the Holocene. From the outset, it is important to keep in mind that this physical geography is an integration of energy, materials, and processes within a much wider global system. The Mediterranean is a zone of convergence and interaction. It is a meeting place not only for tectonic plates, but also for air masses, energy, and river flows from both temperate and tropical latitudes. The region also interacts directly with the global ocean, receiving cool North Atlantic waters in exchange for the warmer and saltier waters produced in the basins of the Mediterranean Sea. It is also a biodiversity hotspot; the Mediterranean has been a meeting place for plants, animals, and humans from three continents throughout much of its history. The chapters in Part I set out the physical and biological framework for the rest of the book and examine key debates about the evolution of the Mediterranean environment. They explore fundamental interactions between the lithosphere, atmosphere, hydrosphere, and biosphere across a range of spatial and temporal scales. The scene is set for later chapters that focus more closely on particular aspects of the Mediterranean environment such as ecosystem dynamics, river basin systems, karst environments, natural hazards, and land degradation. Chapter 1 examines the role of tectonic processes in the development of the Mediterranean landscape and its marine basins. Also highlighted are the dramatic environmental changes and the geomorphological legacy associated with the Messinian Salinity Crisis of the Late Miocene. Chapter 2 focuses on the marine environment, both ancient and modern.