251 research outputs found
Detection and thermal description of medicanes from numerical simulation
Tropical-like cyclones rarely affect the Mediterranean region but they can
produce strong winds and heavy precipitations. These warm-core cyclones,
called MEDICANES (MEDIterranean hurriCANES), are small in size, develop over
the sea and are infrequent. For these reasons, the detection and forecast of
medicanes are a difficult task and many efforts have been devoted to identify
them.
<br><br>
The goals of this work are to contribute to a proper description of these
structures and to develop some criteria to identify medicanes from numerical
weather prediction (NWP) model outputs. To do that, existing methodologies
for detecting, characterizating and tracking cyclones have been adapted to
small-scale intense cyclonic perturbations. First, a mesocyclone detection
and tracking algorithm has been modified to select intense cyclones. Next,
the parameters that define the Hart's cyclone phase diagram are tuned and
calculated to examine their thermal structure.
<br><br>
Four well-known medicane events have been described from numerical simulation
outputs of the European Centre for
Medium-Range Weather Forecast (ECMWF) model. The predicted cyclones and their evolution have
been validated against available observational data and numerical analyses
from the literature
Anàlisis antracològiques a Son Matge i Son Gallard (Valldemossa, Mallorca). Algunes hipòtesis sobre la dinàmica de la vegetació i l’explotació forestal durant el calcolític a Mallor
Mediterranean cyclones in a changing climate. Results from JMA-GSM model
Póster elaborado para la 11th PLINIUS Conference in Mediterranean Storms celebrada del 7 al 11 de septiembre de 2009 en Barcelona.This work has been framed within the MEDEX project, and has had the support from MEDICANES/CGL2008-01271/CLI project, from Spanish Ministerio de Ciencia e Innovación
Genetic Variation in the Population of Ibiza (Spain): Genetic Structure, Geography, and Language
This is the published version, also available here: http://www.jstor.org/stable/41465529
Late Holocene Aleppo pine (Pinus halepensis Miller) woodlands in Mallorca (Balearic Islands, Western Mediterranean): Investigation of their distribution and the role of human management based on anthracological, dendro-anthracological and archaeopalynological data
The pioneering nature of Mediterranean pines and their phytosociological role have been largely discussed in relation to different agents (e.g., edaphic, climatic or anthropogenic). In this context, Aleppo pine is one of the most widespread pine species in the Mediterranean basin, as it is especially adapted to climatic constraints, such as drought and high seasonality, and has a high tolerance for salinity and strong coastal winds. It is also well adapted to regeneration after anthropogenic landscape disturbances, highlighting its important after-fire regeneration rates. In this sense, phytosociological studies conducted in Mediterranean landscapes have found that this species'' wide distribution is mostly due to its rapid regeneration after human landscape transformation, including fire, and the abandonment of agricultural lands. Aleppo pine is considered to broadly develop after human action in sclerophyllous formation, in which it would be scarce or absent without human intervention. Parallel, paleoenvironmental and archaeobotanical studies have attempted to trace these trends back to prehistoric times to investigate this species'' role in Late Pleistocene and Holocene vegetation and evaluate the role of climate and human action in its diachronic dynamics. In this study, we present a compendium of anthracological, dendro-anthracological and archaeopalyonological data with the objective of (i) investigating the nature and distribution of Aleppo pine on the island of Mallorca and (ii) evaluating the possibility that human action could have resulted in the spread of this pine species during the first two millennia of permanent human occupation of the island (c. 2300 cal. BCE–1st-century ACE). Investigating these archaeobotanical datasets, as well as making comparisons with anthracological and paleoenvironmental studies in neighbouring Mediterranean zones (Iberia), allowed us to attest that Aleppo pine is a natural, pre-human component of the Holocene vegetation of the island, and it is especially well-adapted to coastal environments. Moreover, we describe the trends and characteristics of the human management of pine woodlands through anthracology and dendro-anthracology, suggesting that human action did not provoke widespread growth of Aleppo pine in Mallorca at the expense of other vegetation types during prehistory. Such processes, well-documented by current phytosociological studies, probably began at some unknown point after the Romanisation of the island
Evolutionary history of Podarcis tiliguerta on Corsica and Sardinia.
BACKGROUND: Podarcis tiliguerta is a wall lizard endemic to the Mediterranean islands of Corsica and Sardinia. Previous findings of high mtDNA and morphological diversity have led to the suggestion that it may represent a species complex. Here, we analysed mitochondrial and nuclear markers (mtDNA, 3110 bp; 6 nDNA loci, 3961 bp) in P. tiliguerta sampled from thirty-two localities across Corsica and Sardinia. RESULTS: We find much greater intraspecific genetic divergence than between sister species of other Mediterranean island Podarcis, i.e., between P. lilfordi and P. pityusensis. We detected three mtDNA clusters in Corsica (North, South-East and South-West) and either two or three in Sardinia (North vs. South) depending on the clustering method. Only one or two nDNA groups were identified within each main island (again, depending on the method). A Bayesian time-calibrated multispecies coalescent tree was obtained from mtDNA and provided statistical support for a Miocene origin of the species (13.87 Ma, 95% HPD: 18.30-10.77 Ma). The posterior mean divergence time for the Corsican and Sardinian lineages was 12.75 Ma ago (95% HPD: 16.94-9.04 Ma). CONCLUSION: The results support the evolutionary distinctiveness of Corsican and Sardinian populations and also indicate a lack of post-divergence migration despite periods of contact being possible. Further to this, species delimitation analyses of Corsican and Sardinian lineages provided statistical support for their recognition as distinct (sister) taxa. Our results provide new insights into the biogeography of the Mediterranean biodiversity hotspot, and contribute important findings relevant to the systematics and evolution of this speciose lizard genus
Ancient crops provide first archaeological signature of the westward Austronesian expansion
The Austronesian settlement of the remote island of Madagascar remains one of the great puzzles of Indo-Pacific prehistory. Although linguistic, ethnographic, and genetic evidence points clearly to a colonization of Madagascar by Austronesian language-speaking people from Island Southeast Asia, decades of archaeological research have failed to locate evidence for a Southeast Asian signature in the island's early material record. Here, we present new archaeobotanical data that show that Southeast Asian settlers brought Asian crops with them when they settled in Africa. These crops provide the first, to our knowledge, reliable archaeological window into the Southeast Asian colonization of Madagascar. They additionally suggest that initial Southeast Asian settlement in Africa was not limited to Madagascar, but also extended to the Comoros. Archaeobotanical data may support a model of indirect Austronesian colonization of Madagascar from the Comoros and/or elsewhere in eastern Africa
Morphological and genetic diversity of the Balearic lizard,Podarcis lilfordi(Gunther, 1874): Is it relevant to its conservation?
Aims: To characterize the genetic and morphological diversification of the endangered Balearic lizard Podarcis lilfordi and to assess the relevance of this diversity, and how it is described, to conservation measures.
Location: This study covers all the populations of the Balearic lizard, Podarcis lilfordi, present in its range of distribution at coastal islets of Menorca, Mallorca and Cabrera Archipelago.
Methods: We analysed genetic and morphological variation across the 43 known extant populations of the Balearic lizard, using mitochondrial and nuclear markers. We examined morphometric and scalation characters using, in some cases, phylogenetically independent contrasts. We also incorporated the study of dorsal coloration and dorsal colour pattern including the analysis of melanism in several populations.
Results: We detected clear genetic divergence between Menorcan populations and populations from Mallorca and Cabrera, in both nuclear and mtDNA markers, but genetic divergence is relatively low among different insular populations within these groups. In contrast, morphological divergence was substantial both between Menorcan and remaining populations and within these groups. Morphological traits, such as dorsal coloration, body size and the number and size of scales, seemed to be linked with differences in climatic conditions between populations. In addition, some traits, as melanism, showed a strong phylogenetic signal.
Main conclusions: The morphological and genetic diversity of the Balearic lizard is incongruent with the subspecies described in the classical taxonomic literature. Moreover, current populations differ not only in some genetic and morphological features, but also in several ecological and ethological characteristics, in many cases unique to one population. Based on our results, we propose abandoning the use of subspecies to describe the extraordinary morphological diversity of the Balearic lizard and its replacement with the concept of evolutionary significant units (ESUs). ESUs are particularly suitable to describe and recognize such diversity and, especially, to ensure the continuity of the evolutionary process
- …