Primers resultats dels estudis dels elements marmoris del jaciment de l'antiguitat tardana del Pla de Ses Figueres de l'illa de Cabrera

El Pla de ses Figueres és un jaciment que es troba a la riba del port de Cabrera, una petita illa de 1.836 ha. situada en el sud de les illes Balears. Diversos treballs de prospecció i d’excavació han donat a conèixer una important ocupació humana del lloc centrada en els segles V a VII dC. A les zones intervingudes s’han identificat una factoria de salaons, un possible taller de producció de porpra i una necròpoli. En el present treball s’exposaran set peces de marbre localitzades en dit jaciment dintre del projecte “Recuperació, consolidació i museïtzació del monestir bizantí de l’illa de Cabrera”, el qual ja fa dotze anys que finança ininterrompudament l’Ajuntament de Palma.

The Imprint of Geologic History on Within‐Island Diversification of Woodlouse-­Hunter Spiders (Araneae, Dysderidae) in the Canary Islands.

Geological processes and ecological adaptation are major drivers of diversification on oceanic islands. Although diversification in these islands is often interpreted as resulting from dispersal or island hopping rather than vicariance, this may not be the case in islands with complex geological histories. The island of Tenerife, in the Canary Islands, emerged in the late Miocene as 3 precursor islands that were subsequently connected and reisolated by volcanic cycles. The spider Dysdera verneaui is endemic to the island of Tenerife, where it is widely distributed throughout most island habitats, providing an excellent model to investigate the role of physical barriers and ecological adaptation in shaping within-island diversity. Here, we present evidence that the phylogeographic patterns of this species trace back to the independent emergence of the protoislands. Molecular markers (mitochondrial genes cox1, 16S, and nad1 and the nuclear genes ITS-2 and 28S) analyzed from 100 specimens (including a thorough sampling of D. verneaui populations and additional outgroups) identify 2 distinct evolutionary lineages that correspond to 2 precursor islands, each with diagnostic genital characters indicative of separate species status. Episodic introgression events between these 2 main evolutionary lineages explain the observed incongruence between mitochondrial and nuclear markers, probably as a result of the homogenization of their ITS-2 sequence types. The most widespread lineage exhibits a complex population structure, which is compatible with either secondary contact, following connection of deeply divergent lineages, or alternatively, a back colonization from 1 precursor island to another.

The Imprint of Geologic History on Within‐Island Diversification of Woodlouse-­Hunter Spiders (Araneae, Dysderidae) in the Canary Islands.

Geological processes and ecological adaptation are major drivers of diversification on oceanic islands. Although diversification in these islands is often interpreted as resulting from dispersal or island hopping rather than vicariance, this may not be the case in islands with complex geological histories. The island of Tenerife, in the Canary Islands, emerged in the late Miocene as 3 precursor islands that were subsequently connected and reisolated by volcanic cycles. The spider Dysdera verneaui is endemic to the island of Tenerife, where it is widely distributed throughout most island habitats, providing an excellent model to investigate the role of physical barriers and ecological adaptation in shaping within-island diversity. Here, we present evidence that the phylogeographic patterns of this species trace back to the independent emergence of the protoislands. Molecular markers (mitochondrial genes cox1, 16S, and nad1 and the nuclear genes ITS-2 and 28S) analyzed from 100 specimens (including a thorough sampling of D. verneaui populations and additional outgroups) identify 2 distinct evolutionary lineages that correspond to 2 precursor islands, each with diagnostic genital characters indicative of separate species status. Episodic introgression events between these 2 main evolutionary lineages explain the observed incongruence between mitochondrial and nuclear markers, probably as a result of the homogenization of their ITS-2 sequence types. The most widespread lineage exhibits a complex population structure, which is compatible with either secondary contact, following connection of deeply divergent lineages, or alternatively, a back colonization from 1 precursor island to another.

The Imprint of Geologic History on Within‐Island Diversification of Woodlouse-­Hunter Spiders (Araneae, Dysderidae) in the Canary Islands.

Geological processes and ecological adaptation are major drivers of diversification on oceanic islands. Although diversification in these islands is often interpreted as resulting from dispersal or island hopping rather than vicariance, this may not be the case in islands with complex geological histories. The island of Tenerife, in the Canary Islands, emerged in the late Miocene as 3 precursor islands that were subsequently connected and reisolated by volcanic cycles. The spider Dysdera verneaui is endemic to the island of Tenerife, where it is widely distributed throughout most island habitats, providing an excellent model to investigate the role of physical barriers and ecological adaptation in shaping within-island diversity. Here, we present evidence that the phylogeographic patterns of this species trace back to the independent emergence of the protoislands. Molecular markers (mitochondrial genes cox1, 16S, and nad1 and the nuclear genes ITS-2 and 28S) analyzed from 100 specimens (including a thorough sampling of D. verneaui populations and additional outgroups) identify 2 distinct evolutionary lineages that correspond to 2 precursor islands, each with diagnostic genital characters indicative of separate species status. Episodic introgression events between these 2 main evolutionary lineages explain the observed incongruence between mitochondrial and nuclear markers, probably as a result of the homogenization of their ITS-2 sequence types. The most widespread lineage exhibits a complex population structure, which is compatible with either secondary contact, following connection of deeply divergent lineages, or alternatively, a back colonization from 1 precursor island to another.

Recherches sur l'occupation d'Althiburos (région du Kef, Tunisie) et de ses environs à l'èpoque numide

El desenvolupament durant els anys 2006-2007 del projecte de recerca sobre la formació de l'Estat númida ha revelat l'existència a Althiburos d'un hàbitat preromà d'extensió considerable (almenys 4 ha), l'origen del qual remunta com a mínim al segle VI aC. La prospecció del territori adjacent ha mostrat l'existència de diversos jaciments númides de dimensions més reduïdes, d'algunes estructures funeràries de la mateixa època i d'una cinquantena de dòlmens, la datació dels quals (tal vegada del Bronze final), roman encara incerta. Les dades obtingudes permeten situar en el segle VI aC, o fins i tot abans, l'inici del procés de complexificació social que va conduir a la formació dels regnes númides.

Centrality and investment strategies at the beginning of industrialisation in mid-nineteenth-century Catalonia

We apply social networks analysis to the study of an important database on investment and companies" share in the Catalonia (Spain) of the nineteenth century. In contrast with most of the existing related literature, usually addressing power relationships across administration boards, we focus on the structure of interactions among individual investors and firms. Centrality analysis uncovers interesting roles played by certain economic sectors (e.g. textile and financial). Furthermore, the diverse composition (in terms of economic activity) of communities in the network (subgroups more densely connected internally than with the rest of the network) reveals a high investment diversification, which nicely agrees with a known characteristic of traditional Catalan business strategies.

The measurement of ice velocity, mass balance and thinning-rate on Johnsons Glacier, Livingston Island, South Shetland Islands, Antarctica

A network of twenty stakes was set up on Johnsons Glacier in order to determine its dynamics. During the austral summers from 1994-95 to 1997-98, we estimated surface velocities, mass balances and ice thickness variations. Horizontal velocity increased dow nstream from 1 m a- 1 near the ice divides to 40 m a- 1 near the ice terminus. The accumulation zone showed low accumulation rates (maximum of 0,6 m a- 1 (ice)), whereas in the lower part of the glacier, ablation rates were 4,3 m a- 1 (ice). Over the 3-year study period, both in the accumulation and ablation zones, we detected a reduction in the ice surface level ranging from 2 to 10 m from the annual ve rt ical velocities and ice-thinning data, the mass balance was obtained and compared with the mass balance field values, resulting in similar estimates. Flux values were calculated using cross-section data and horizontal velocities, and compared with the results obtained by means of mass balance and ice thinning data using the continuity equation. The two methods gave similar results.

Biogeochemical processes controlling oxygen and carbon isotopes of diatom silica in Late Glacial to Holocene lacustrine rhythmites

Biogeochemical cycles and sedimentary records in lakes are related to climate controls on hydrology and catchment processes. Changes in the isotopic imposition of the diatom frustules (δ 18 O diatom and δ 13 C diatom ) in lacustrine sediments can be used to reconstruct palaeoclimatic and palaeoenvironmental changes. The Lago Chungará (Andean Altiplano, 18°15 ′ S, 69°10 ′ W, 4520 masl) diatomaceous laminated sediments are made up of white and green multiannual rhythmites. White laminae were formed during short-term diatom super-blooms, and are composed almost exclusively of large-sized Cyclostephanos andinus.These diatoms bloom during mixing events when recycled nutrients from the bottom waters are brought to the surface and/or when nutrients are introduced from the catchment during periods of strong runoff. Conversely, the green laminae are thought to have been deposited over several years and are composed of a mixture of diatoms (mainly smaller valves of C. andinus and Discostella stelligera ) and organic matter. These green laminae reflect the lake's hydrological recovery from a status favouring the diatom super-blooms (white laminae) towards baseline conditions. δ 18 O diatom and δ 13 C diatom from 11,990 to 11,530 cal years BP allow us to reconstruct shifts in the precipitation/evaporation ratio and changes in the lake water dissolved carbon concentration, respectively. δ 18 O diatom values indicate that white laminae formation occurred mainly during low lake level stages, whereas green laminae formation generally occurred during high lake level stages. The isotope and chronostratigraphical data together suggest that white laminae deposition is caused by extraordinary environmental events. El Niño-Southern Oscillation and changes in solar activity are the most likely climate forcing mechanisms that could trigger such events, favouring hydrological changes at interannual-to-decadal scale. This study demonstrates the potential for laminated lake sediments to document extreme pluriannual events.

Mesozoic geology of Cape Shirreff, Livingston Island, South Shetland Islands, Antarctica.

Al Cap de Shirr e ff (Fig. 1) hi aflora una successió volcànica de com a mínim 450 m de potència, constituïda principalment per laves i, en menor proporció, bretxes vulcanoclàstiques (Fig. 2). Les laves són basalts olivínics subalcalins i andesites basàltiques, que generalment tenen un aspecte massiu. Tot i això, la successió volcànica localment forma una alternança decimètrica de nivells durs i tous, amb potències va r i a bles i presència local de discordances angulars i onlaps, que reflecteixen geometries deposicionals complexes. A la zona nord del Cap de Shirr e ff hi ha aflorament de bretxes vulcanoclàstiques d"aspecte massiu, que localment tenen intercalacions de laves...

Macrofossils in Raraku Lake (Easter Island) integrated with sedimentary and geochemical records towards a palaeoecological synthesis for the last 34,000 years

Macrofossil analysis of a composite 19 m long sediment core from Rano Raraku Lake (Easter Island)was related to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochemical data (Principal Component Analysis) shows that macrofossil associations provide sound palaeolimnological information in conjunction with sedimentary data. The main taphonomic factors in fluencing the macrofossil assemblages are run-off from the catchment, the littoral plant belt, and the depositional environment within the basin. Five main stages during the last 34,000 calibrated years BP (cal yr BP) are characterised from the lithological, geochemical, and macrofossil data. From 34 to 14.6 cal kyr BP (last glacial period) the sediments were largely derived from the catchment, indicating a high energy lake environment with much erosion and run-off bringing abundant plant trichomes, lichens, and mosses into the centre of Raraku Lake.

Study of Johnsons Glacier (Livingston Island, Antarctica) by means of shallow ice cores and their tephra and by analysis of 137Cs content

With the aim of monitoring the dynamics of the Livingston Island ice cap, the Departament de Geodinàmica i Geofísica of the Universitat de Barcelona began ye a r ly surveys in the austral summer of 1994-95 on Johnsons Glacier. During this field campaign 10 shallow ice cores were sampled with a manual ve rtical ice-core drilling machine. The objectives were: i) to detect the tephra layer accumulated on the glacier surface, attributed to the 1970 Deception Island pyroclastic eruption, today interstratified; ii) to verify wheter this layer might serve as a reference level; iii) to measure the 1 3 7Cs radio-isotope concentration accumulated in the 1965 snow stratum; iv) to use the isochrone layer as a mean of verifying the age of the 1970 tephra layer; and, v) to calculate both the equilibrium line of the glacier and average mass balance over the last 28 years (1965-1993). The stratigr a p hy of the cores, their cumulative density curves and the isothermal ice temperatures recorded confi rm that Johnsons Glacier is a temperate glacier. Wi n d, solar radiation heating and liquid water are the main agents controlling the ve rtical and horizontal redistribution of the volcanic and cryoclastic particles that are sedimented and remain interstratified within the g l a c i e r. It is because of this redistribution that the 1970 tephra layer does not always serve as a ve ry good reference level. The position of the equilibrium line altitude (ELA) in 1993, obtained by the 1 3 7Cs spectrometric analysis, varies from about 200 m a.s.l. to 250 m a.s.l. This indicates a rising trend in the equilibrium line altitude from the beginning of the 1970s to the present day. The va rying slope orientation of Johnsons Glacier relative to the prevailing NE wind gives rise to large local differences in snow accumulation, which locally modifies the equilibrium line altitude. In the cores studied, 1 3 7Cs appears to be associated with the 1970 tephra laye r. This indicates an intense ablation episode throughout the sampled area (at least up to 330 m a.s.l), which probably occurred synchronically to the 1970 tephra deposition or later. A rough estimate of the specific mass balance reveals a considerable accumulation gradient related to the increase with altitude.

The El Masnou Infralittoral sedimentary environment (Barcelona province, NW Mediterranean Sea): morphology and Holocene seismic stratigraphy

A detailed analysis of the morphology and the Holocene seismic and sequence stratigraphy and architecture of the infralittoral sedimentary environment of the El Masnou coast (Catalonia, NW Mediterranean Sea) was carried out using multibeam bathymetry and GeoPulse seismic data. This environment extends down to 26-30 m water depth, and is defined morphologically by two depositional wedges whose seafloor is affected by erosive furrows, slides, fields of large- and small-scale wavy bedforms, and dredging trenches and pits. Erosive terraces are also identified in the transition domain toward the inner continental shelf. The Holocene stratigraphy of the infralittoral environment is defined by two major seismic sequences (lower and upper), each one formed by internal seismic units. The sequences and units are characterised by downlapping surfaces made up of deposits formed by progradation of coastal lithosomes. The stratigraphy and stratal architecture, displaying a retrogradational arrangement with progradational patterns of minor order, were controlled by different sea-level positions. The stratigraphic division represents the coastal response to the last fourth-order transgressive and highstand conditions, modulated by small-scale sea-level oscillations (≈1-2 m) of fith to sixth order. This study also highlights the advantage of an integrated analysis using acoustic/seismic methods for practical assessment of the anthropogenic effects on infralittoral domains based on the association of marine geological observations.

Landscape Systems and Human Land-Use Interactions in Mediterranean Highlands and Littoral Plains during the Late Holocene: Integrated Analysis from the InterAmbAr Project (North-Eastern Catalonia).

The main goal of the InterAmbAr reseach project is to analyze the relationships between landscape systems and human land-use strategies on mountains and littoral plains from a long-term perspective. The study adopts a high resolution analysis of small-scale study areas located in the Mediterranean region of north-eastern Catalonia. The study areas are distributed along an altitudinal transect from the high mountain (above 2000m a.s.l.) to the littoral plain of Empordà (Fig. 1). High resolution interdisciplinary research has been carried out from 2010, based on the integration of palaeoenvironmental and archaeological data. The micro-scale approach is used to understand human-environmental relationships. It allows better understanding of the local-regional nature of environmental changes and the synergies between catchment-based systems, hydro-sedimentary regimes, human mobility, land-uses, human environments, demography, etc.

Population connectivity buffers genetic diversity loss in a seabird

Background Ancient DNA has revolutionized conservation genetic studies as it allows monitoring of the genetic variability of species through time and predicting the impact of ecosystems" threats on future population dynamics and viability. Meanwhile, the consequences of anthropogenic activities and climate change to island faunas, particularly seabirds, remain largely unknown. In this study, we examined temporal changes in the genetic diversity of a threatened seabird, the Cory"s shearwater (Calonectris borealis). Findings We analysed the mitochondrial DNA control region of ancient bone samples from the late-Holocene retrieved from the Canary archipelago (NE Atlantic) together with modern DNA sequences representative of the entire breeding range of the species. Our results show high levels of ancient genetic diversity in the Canaries comparable to that of the extant population. The temporal haplotype network further revealed rare but recurrent long-distance dispersal between ocean basins. The Bayesian demographic analyses reveal both regional and local population size expansion events, and this is in spite of the demographic decline experienced by the species over the last millennia. Conclusions Our findings suggest that population connectivity of the species has acted as a buffer of genetic losses and illustrate the use of ancient DNA to uncover such cryptic genetic events.