The intriguing biogeographic pattern of the Italian wall lizard Podarcis siculus (Squamata: Lacertidae) in the Tuscan Archipelago reveals the existence of a new ancient insular clade

The Tuscan Archipelago is one of the most ancient and ecologically heterogeneous island systems in the Mediterranean. The biodiversity of these islands was strongly shaped by the Pliocene and Pleistocene sea regressions and transgression, resulting in different waves of colonization and isolation of species coming from the mainland. The Italian wall lizard, Podarcis siculus, is present on the following islands of the Tuscan Archipelago: Elba, Giglio, Giannutri, Capraia, Montecristo and Cerboli. The species in the area displays a relatively high morphological variability that in the past led to the description of several subspecies. In this study, both the genetic and morphological diversity of P. siculus of the Tuscan Archipelago were investigated. Specifically, the meristic characters and the dorsal pattern were analyzed, while the genetic relationships among these populations were explored with mtDNA and microsatellite nuclear markers to reconstruct the colonization history of the Archipelago. Our results converge in the identification of at least two different waves of colonization in the Archipelago: Elba, and the populations of Cerboli and Montecristo probably originate from historical introductions from mainland Tuscany, while those of Giglio and Capraia are surviving populations of an ancient lineage which colonized the Tuscan Archipelago during the Pliocene and which shares a common ancestry with the P. siculus populations of south-eastern Italy. Giannutri perhaps represents an interesting case of hybridization between the populations from mainland Tuscany and the Giglio-Capraia clade. Based on the high phenotypic and molecular distinctiveness of this ancient clade, these populations should be treated as distinct units deserving conservation and management efforts as well as further investigation to assess their taxonomic status

Castanea sativa Ancient Trees Across Europe: Genetic Diversity And Conservation Strategy

Long-living trees are witnesses of environmental changes and human interventions; these extraordinary organisms not only represent a historical, landscape and environmental heritage of inestimable value, but they also are a reserve of genetic variability which can considered as a great resource for management programs of forest species. This is the first genetic study on Italian ancient chestnut trees (Castanea sativa Mill.). Ninety-nine ancient trees including the oldest known chestnut in Europe, named ‘Cento Cavalli’, which is believed to be to be between 3,000 and 4,000 years old, were collected. For each tree, more than one sample from canopy and root suckers was collected to test for the genetic integrity of the individuals The samples were genotyped using nine nuclear microsatellite markers (nSSRs) and two chloroplast markers (cpDNA). Genetic variability indices were evaluated using GeneAlEx 6.5, GenoDive 3.0 and HP-rare software. We identified a total of 106 unique genetic profiles within the analyzed individuals. A Bayesian analysis was performed using the software STRUCTURE to unveil the genetic relationships existing between the genotyped individuals. We were able to identify a geographic pattern of genetic diversity among the old chestnut trees. In addition, the genetic similarity among the ancient trees and the close chestnut populations to was studied. A phylogeographic structure of plastid diversity was also established. Our results contribute to evaluate the European chestnut genetic resources, gave insights to its domestication history and to define the best conservation and management strategies

Monumental chestnut trees: source of genetic diversity, cultural and landscape value

The monumental trees are unique individuals of venerable age and considerable size, which represent a heritage of inestimable historical, cultural, landscape, and scientific value for the territtory. They also constitute a source of genetic diversity which confers them longevity and ability to adapt to climate and environmental changes. In this context, studies on centennial trees can be useful for interpretatiton of species history as migration events, selection and anthropogenic actiton. The aim of this research was to evaluate the genetic variability of ancient Castanea sativa trees and relate them to actual natural/naturalized populatitons and varieties in order to enhance our knowledge about the demography, cultivatiton processes and the impact of these giant trees on the genetic diversity of the species. We selected a total of 182 ancient trees from Spain and Central - Southern Italy. For each tree, more than one sample was collected to test for genetic integrity and grafing. The samples were genotyped by means of nuclear microsatellite markers and the variability of plastid DNA regitons (trnH-psbA and trnK/matK) was also tested. Using the sofware GeneALex and HPrare, we evaluated observed (Hto) and expected (He) heterozygosity, allelic richness (Ar) private allelic richness (pAr). A Bayesian analysis was performed using the sofware STRUCTURE to identify the different gene pools and gentotypes. The obtained genetic data were compared with those of natural populations and cultivars collected in the same geographic areas. Higher values of allelic richness were observed in the ancient chestnut trees, a genetic similarity of these individual trees to the natural populations was highlighted. A phylogetographic structure of plastid diversity was alsto established. Eleven genotypes were coincident with 11 cultivars in the EU database. Based on the putative age of giant trees we can hyptothesize that the grafing practice occurred in the Iberian peninsula in the 15th century and in the 17th century in Italy. This work provides new knowledge about the history and domesticatiton tof European chestnut, the results are relevant for the conservatiton and management of Castanea sativa genetic resources

DNA analysis of Castanea sativa (sweet chestnut) in Britain and Ireland: Elucidating European origins and genepool diversity

Castanea sativa is classified as non-indigenous in Britain and Ireland. It was long held that it was first introduced into Britain by the Romans, until a recent study found no corroborative evidence of its growing here before c. AD 650. This paper presents new data on the genetic diversity of C. sativa in Britain and Ireland and potential ancestral sources in continental Europe. Microsatellite markers and analytical methods tested in previous European studies were used to genotype over 600 C. sativa trees and coppice stools, sampled from ancient semi-natural woodlands, secondary woodlands and historic cultural sites across Britain and Ireland. A single overall genepool with a diverse admixture of genotypes was found, containing two sub groups differentiating Wales from Ireland, with discrete geographical and typological clusters. C. sativa genotypes in Britain and Ireland were found to relate predominantly to some sites in Portugal, Spain, France, Italy and Romania, but not to Greece, Turkey or eastern parts of Europe. C. sativa has come to Britain and Ireland from these western European areas, which had acted as refugia in the Last Glacial Maximum; we compare its introduction with the colonization/translocation of oak, ash, beech and hazel into Britain and Ireland. Clones of C. sativa were identified in Britain, defining for the first time the antiquity of some ancient trees and coppice stools, evincing both natural regeneration and anthropogenic propagation over many centuries and informing the chronology of the species’ arrival in Britain. This new evidence on the origins and antiquity of British and Irish C. sativa trees enhances their conservation and economic significance, important in the context of increasing threats from environmental change, pests and pathogens

Landscape genetics structure of European sweet chestnut (Castanea sativa Mill): indications for conservation priorities

Sweet chestnut is a tree of great economic (fruit and wood production), ecological and cultural importance in Europe. A large-scale landscape genetic analysis of natural populations of sweet chestnut across Europe is applied to 1) evaluate the geographic patterns of genetic diversity 2) identify spatial coincidences between genetic discontinuities and geographic barriers 3) propose certain chestnut populations as reservoirs of genetic diversity for conservation and breeding programmes. Six polymorphic microsatellite markers were used for genotyping 1608 wild trees sampled in 73 European sites. The Geostatistical IDW technique (ArcGIS 9.3) was used to produce maps of genetic diversity parameters (He, Ar, PAr) and a synthetic map of the population membership (Q value) to the different gene pools. Genetic barriers were investigated using BARRIER 2.2 software and their locations were overlaid on a Digital Elevation Model (GTOPO30). The DIVA-GIS software was used to propose priority areas for conservation. High values of genetic diversity (He) and allelic richness (Ar) were observed in the central area of C. sativa's European distribution range. The highest values of private allelic richness (PAr) were found in the eastern area. Three main gene pools and a significant genetic barrier separating the eastern from the central and western populations were identified. Areas with high priority for genetic conservation were indicated in Georgia, eastern Turkey and Italy. Our results increase knowledge of the biogeographic history of C. sativa in Europe, indicate the geographic location of different gene pools and identify potential priority reservoirs of genetic diversity

Teoria dei sistemi. Lineari stazionari a dimensione finita

Quali sono i fondamenti teorici che sono alla base del comportamento dei sistemi complessi? Come comprendere e valutare le prestazioni di un sistema che si comporta in maniera autonoma? La Teoria dei Sistemi ci dà gli strumenti per comprendere e ci introduce ai metodi di progetto nel sorprendente mondo dell'Automatica. Dopo una breve introduzione destinata ad illustrare in modo succinto il punto di vista dell'Automatica, viene presentata la classe di modelli che sono oggetto di studio: si tratta delle rappresentazioni con lo stato lineari, stazionarie a dimensione finita, sia a tempo continuo che discreto. Lo studio nel dominio del tempo e della variabile complessa, sino alla caratterizzazione del comportamento in frequenza consente di mettere in evidenza i riscontri applicativi ai risultati teorici. Lo studio della stabilità interna ed esterna, delle proprietà dello spazio di stato, dei modelli dei sistemi interconnessi e delle loro proprietà in relazione a quelle dei componenti, sono i tasselli di un mosaico dei metodi fondamentali che vengono illustrati. La loro utilità nella valutazione delle prestazioni e nel progetto dei sistemi di controllo viene messa in luce nell'ultimo capitolo dove viene studiato il problema della modifica della dinamica con controreazione dall'uscita

The Intriguing Biogeographic Pattern of the Italian Wall Lizard Podarcis siculus (Squamata: Lacertidae) in the Tuscan Archipelago Reveals the Existence of a New Ancient Insular Clade

The Tuscan Archipelago is one of the most ancient and ecologically heterogeneous island systems in the Mediterranean. The biodiversity of these islands was strongly shaped by the Pliocene and Pleistocene sea regressions and transgression, resulting in different waves of colonization and isolation of species coming from the mainland. The Italian wall lizard, Podarcis siculus, is present on the following islands of the Tuscan Archipelago: Elba, Giglio, Giannutri, Capraia, Montecristo and Cerboli. The species in the area displays a relatively high morphological variability that in the past led to the description of several subspecies. In this study, both the genetic and morphological diversity of P. siculus of the Tuscan Archipelago were investigated. Specifically, the meristic characters and the dorsal pattern were analyzed, while the genetic relationships among these populations were explored with mtDNA and microsatellite nuclear markers to reconstruct the colonization history of the Archipelago. Our results converge in the identification of at least two different waves of colonization in the Archipelago: Elba, and the populations of Cerboli and Montecristo probably originate from historical introductions from mainland Tuscany, while those of Giglio and Capraia are surviving populations of an ancient lineage which colonized the Tuscan Archipelago during the Pliocene and which shares a common ancestry with the P. siculus populations of south-eastern Italy. Giannutri perhaps represents an interesting case of hybridization between the populations from mainland Tuscany and the Giglio-Capraia clade. Based on the high phenotypic and molecular distinctiveness of this ancient clade, these populations should be treated as distinct units deserving conservation and management efforts as well as further investigation to assess their taxonomic status