http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 23 May 2013 11:13:53 GMT 2013-05-23T11:13:53Z http://hdl.handle.net/2067/681 Title: Filogeografia di Talpa romana in Italia meridionale Authors: Cecchetti, Silvia Abstract: Gli organismi fossori sono caratterizzati da livelli di variabilità genetica modesti, a causa dell’omogeneità del loro ambiente. L’insettivoro Talpa romana, endemico dell’Italia centromeridionale, mostra livelli di variabilità genetica del tutto confrontabili con quelli di altri mammiferi fossori, tranne che nelle popolazioni della Calabria centro-meridionale. Un’analisi di sistemi gene-enzima ha dimostrato la presenza di un contatto secondario nella Piana di Catanzaro tra due entità isolate, una tipica dell’Appennino centro-meridionale, l’altra dell’Aspromonte. L’aumentata variabilità sarebbe dovuta all’ibridazione tra le due forme grazie alla definitiva emersione della Piana di Catanzaro. Per indagare più approfonditamente i processi di differenziamento e contatto secondario descritti, sono stati sequenziati un frammento del citocromo b (mtDNA) e due introni del cromosoma Y (DNA nucleare). Il primo marcatore ha permesso di distinguere quattro gruppi di aplotipi mitocondriali la cui distribuzione geografica è in buona misura coincidente con i principali massicci montuosi della regione. L’uso del cromosoma Y (introni UTY11 e DBY14) ha permesso di tracciare lo spostamento dei soli maschi, caratterizzati da una maggiore mobilità: un gruppo risulta limitato all’Aspromonte ma il secondo estende il flusso genico dall’Italia centrale all’Aspromonte. Il confronto tra i vari i marcatori mostra un quadro corrispondente agli eventi paleogeografici verificatisi in Calabria.; The subterranean organisms are characterized by low genetic variability levels, due to the homogenous environment they live in. The worm-eating Talpa romana, endemic species of central and southern Italy, shows genetic variability levels comparable with those of other subterranean mammals, except for central and southern Calabria populations. The multilocus electrophoresis analysis has evidenced an hybrid zone in the Catanzaro plain between two isolated units, the first one in central and southern Appennines and the second one in Aspromonte. The increased variability might be due to hybridation between the two groups, occurred after the definitive emersion of the Catanzaro plain. In order to analyze the differentiation processes and secondary contact zones, it was sequenced a cytochrome b fragment gene (mtDNA) and two introns of Y chromosome (nuclear DNA). The first marker has allowed highlighting four groups of mitochondrial haplotypes whose geographic distribution is coincident with the main mountains of the region. The use of the Y chromosome (introns UTY11 and DBY14) allowed tracing the movement of the males having greater mobility: one group is confined in the Aspromonte, while the second one spreads its gene flow from the Central Italy to the Aspromonte. The comparison between the several markers used shows a scenario in agreement with the palegeographic events occurred in Calabria. Description: Dottorato di ricerca in Ecologia e gestione delle risorse biologiche Tue, 23 Jun 2009 22:00:00 GMT http://hdl.handle.net/2067/681 2009-06-23T22:00:00Z http://hdl.handle.net/2067/1714 Title: Birth of a hotspot of intraspecific genetic diversity: notes from the underground Authors: Canestrelli, Daniele; Aloise, Gaetano; Cecchetti, Silvia; Nascetti, Giuseppe Abstract: Hotspots of intraspecific diversity have been observed in most species, often within areas of putative Pleistocene refugia. They have thus mostly been viewed as the outcome of prolonged stability of large populations within the refugia. However, recent evidence has suggested that several other microevolutionary processes could also be involved in their formation. Here, we investigate the contribution of these processes to current range-wide patterns of genetic diversity in the Italian endemic mole Talpa romana, using both nuclear (30 allozyme loci) and mitochondrial markers (cytochrome b sequences). Southern populations of this species showed an allozyme variation that is amongst the highest observed in small mammals (most populations had an expected heterozygosity of 0.10 or above), which was particularly unexpected for a subterranean species. Population genetic, phylogeographic and historical demographic analyses indicated that T. romana populations repeatedly underwent allopatric differentiations followed by secondary admixture within the refugial range in southern Italy. A prolonged demographic stability was reliably inferred from the mitochondrial DNA data only for a population group located north and east of the Calabrian peninsula, showing comparatively lower levels of allozyme variability, and lacking evidence of secondary admixture with other groups. Thus, our results point to the admixture between differentiated lineages as the main cause of the higher levels of diversity of refugial populations. When compared with the Pleistocene evolutionary history recently inferred for species from both the same and other geographic regions, these results suggest the need for a reappraisal of the role of gene exchange in the formation of intraspecific hotspots of genetic diversity. Description: L'articolo è disponibile sul sito dell'editore http://onlinelibrary.wiley.com/ Thu, 31 Dec 2009 23:00:00 GMT http://hdl.handle.net/2067/1714 2009-12-31T23:00:00Z