http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 23 May 2013 08:28:44 GMT 2013-05-23T08:28:44Z http://hdl.handle.net/2067/1794 Title: Additional records of metazoan parasites from Caribbean marine mammals, including genetically identified anisakid nematodes Authors: Colón-Llavina, Marlene M.; Mignucci-Giannoni, Antonio A.; Mattiucci, Simonetta; Paoletti, Michela; Nascetti, Giuseppe; Williams Jr., Ernest H. Abstract: Studies of marine mammal parasites in the Caribbean are scarce. An assessment for marine mammal endo- and ectoparasites from Puerto Rico and the Virgin Islands, but extending to other areas of the Caribbean, was conducted between 1989 and 1994. The present study complements the latter and enhances identification of anisakid nematodes using molecular markers. Parasites were collected from 59 carcasses of stranded cetaceans and manatees from 1994 to 2006, including Globicephala macrorhynchus, Kogia breviceps, Kogia sima, Lagenodelphis hosei, Mesoplodon densirostris, Peponocephala electra, Stenella longirostris, Steno bredanensis, Trichechus manatus. Tursiops truncatus, and Ziphius cavirostris. Sixteen species of endoparasitic helminthes were morphologically identified, including two species of acanthocephalans (Bolbosoma capitatum, Bolbosoma vasculosum), nine species of nematodes (Anisakis sp., Anisakis brevispiculata, Anisakis paggiae, Anisakis simplex, Anisakis typica, Anisakis ziphidarium, Crassicauda anthonyi, Heterocheilus tunicatus, Pseudoterranova ceticola), two species of cestodes (Monorygma grimaldi, Phyllobothrium delphini), and three species of trematodes (Chiorchis groschafti, Pulmonicola cochleotrema, Monoligerum blairi). The nematodes belonging to the genus Anisakis recovered in some stranded animals were genetically identified to species level based on their sequence analysis of mitochondrial DNA (629 bp of mtDNA cox 2). A total of five new host records and six new geographic records are presented. Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com/ Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2067/1794 2008-12-31T23:00:00Z http://hdl.handle.net/2067/1793 Title: Helminth communities of loggerhead turtles (Caretta caretta) from Central and Western Mediterranean Sea: the importance of host's ontogeny Authors: Santoro, Mario; Badillo, Francisco J.; Mattiucci, Simonetta; Nascetti, Giuseppe; Bentivegna, Flegra; Isacco, Gianni; Travaglini, Andrea; Paoletti, Michela; Kinsella, John M.; Tomas, Jesus; Raga, Juan A.; Aznar, Francisco J. Abstract: We investigated the factors providing structure to the helminth communities of 182 loggerhead sea turtles, Caretta caretta, collected in 6 localities from Central and Western Mediterranean. Fifteen helminth taxa (10 digeneans, 4 nematodes and 1 acanthocephalan) were identified, of which 12 were specialist to marine turtles; very low numbers of immature individuals of 3 species typical from fish or cetaceans were also found. These observations confirm the hypothesis that phylogenetic factors restrict community composition to helminth species specific to marine turtles. There were significant community dissimilarities between turtles from different localities, the overall pattern being compatible with the hypothesis that parasite communities reflect the ontogenetic shift that juvenile loggerheads undergo from oceanic to neritic habitats. The smallest turtles at the putative oceanic, pelagic-feeding stage harboured only the 2 digenean species that were regionally the most frequent, i.e. Enodiotrema megachondrus and Calycodes anthos; the largest turtles at the putative neritic, bottom-feeding stage harboured 11 helminth taxa, including 3 nematode species that were rare or absent in turtles that fed partially on pelagic prey. Mean species richness per host was low (range: 1.60–1.89) and did not differ between localities. Variance ratio tests indicated independent colonization of each helminth species. Both features are expected in ectothermic and vagrant hosts living in the marine environment. Description: L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.com Thu, 31 Dec 2009 23:00:00 GMT http://hdl.handle.net/2067/1793 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1799 Title: Genetic diversity of the killifish Aphanius fasciatus paralleling the environmental changes of Tarquinia salterns habit Authors: Angeletti, Dario; Cimmaruta, Roberta; Nascetti, Giuseppe Abstract: The habitat in the Natural Reserve of the Tarquinia salterns, located on the Tyrrhenian coast of central Italy, has undergone dramatic alterations over the last 10 years. After salt production was terminated in 1997 the site was abandoned until 2002, with consequent degradation of habitat quality and stiffening of the environmental conditions. From 2003 to 2006 ecological rehabilitation of the site was carried out, restoring water circulation to its previous equilibrium. The genetic variation in the killifish Aphanius fasciatus inhabiting the salterns was monitored using allozymes from 1998. The results showed that the genetic variability of the killifish strongly reduced through time: a high number of rare alleles were lost and both heterozygosity and allele richness were significantly decreased. The most recent samples, taken after the ecological restoration, showed that to date the genetic erosion of A. fasciatus gene pool has slowed down, since no significant differences have been detected for any genetic variability parameter. Concerning the mechanisms leading to the impoverishment of the genetic variability, the strong loss of rare alleles suggests a role of genetic drift, which accords with the fluctuation of the effective population size recorded over the period of study and with the low gene flow typical of this species. The low levels of gene flow reported for this species imply that once lost, the genetic variability can rarely be restored through immigration from highly variable populations. Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com Thu, 31 Dec 2009 23:00:00 GMT http://hdl.handle.net/2067/1799 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1800 Title: Genetic structure and temporal stability in the horse mackerel (Trachurus trachurus) Authors: Cimmaruta, Roberta; Bondanelli, Paola; Ruggi, Alessandra; Nascetti, Giuseppe Abstract: This study aimed at assessing the temporal and spatial genetic structure of the horse mackerel (Trachurus trachurus) using allozymes, within the frame of a multidisciplinary research project directed at the stock assessment of this species. To this end, 19 samples were taken from a large part of the geographical range of the species, providing more than 2200 specimens analysed. Samples from 14 localities were caught twice in different years, so that the temporal stability of their genetic structure could be investigated. The genotypes and the allele frequencies obtained at different times from the same locality were statistically consistent, suggesting that the genetic structure of horse mackerel populations is stable overtime. Allozyme analysis showed that all the horse mackerel populations studied, although geographically separated, were genetically homogeneous and connected by high levels of gene flow. Attempts to highlight subtle genetic structure only revealed a slight differentiation between eastern Mediterranean samples (Ionian and Aegean Seas) versus the western Mediterranean and Atlantic ones, in agreement with the horse mackerel’s migration routes so far identified and with the results obtained using different approaches (parasites as biological tags, otoliths). A further objective of the research was to assess the level of genetic variability in this species. We found very high variability in all the studied samples, among the highest recorded in the literature for many pelagic and demersal fishes. Since the levels of genetic variability are increasingly used as indicators of the state of exploited and human-impacted populations, the results obtained suggested that the biomass depletion suffered by the horse mackerel has not impoverished its genetic resources yet. However, it is worth noting that the significantly lowest values were recorded for the samples from the so-called north-western stock, where the catches are rapidly decreasing since 1996. Description: L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.com Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2067/1800 2007-12-31T23:00:00Z http://hdl.handle.net/2067/1709 Title: Advances and Trends in the Molecular Systematics of Anisakid Nematodes, with Implications for their Evolutionary Ecology and Host—Parasite Co-evolutionary Processes Authors: Mattiucci, Simonetta; Nascetti, Giuseppe Abstract: The application of molecular systematics to the anisakid nematodes of the genera Anisakis, Pseudoterranova and Contracaecum, parasites of aquatic organisms, over the last two decades, has advanced the understanding of their systematics, taxonomy, ecology and phylogeny substantially. Here the results of this effort on this group of species from the early genetic works to the current status of their revised taxonomy, ecology and evolutionary aspects are reviewed for each of three parasitic groups. It has been shown that many anisakid morphospecies of Anisakis, Contracaecum and Pseudoterranova include a certain number of sibling species. Molecular genetic markers provided a rapid, precise means to screen and identify several species that serve as definitive and intermediate and or/paratenic hosts of the so far genetically characterized species. Patterns of differential distribution of anisakid nematodes in various definitive and intermediate hosts are presented. Differences in the life history of related species can be due both to differential host—parasite co-adaptation and co-evolution, and/or to interspecific competition, that can reduce the range of potential hosts in sympatric conditions. Phylogenetic hypotheses attempted for anisakid nematodes and the possible evolutionary scenarios that have been proposed inferred from molecular data, also with respect to the phylogeny of their hosts are presented for the parasite—host associations Anisakis-cetaceans and Contracaecum-pinnipeds, showing that codivergence and host-switching events could have accompanied the evolution of these groups of parasites. Finally, examples in which anisakid nematodes recognized genetically at the species level in definitive and intermediate/paratenic hosts from various geographical areas of the Boreal and Austral regions and their infection levels have been used as biological indicators of fish stocks and food-web integrity in areas at high versus low levels of habitat disturbance (pollution, overfishing, by-catch) are presented. Description: L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.com/ Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2067/1709 2007-12-31T23:00:00Z 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 http://hdl.handle.net/2067/1764 Title: Association of riparian features and water chemistry with reed litter breakdown in a volcanic lake (Lake Vico, Italy) Authors: Costantini, Maria Letizia; Rossi, Loreto; Scialanca, Fabrizio; Rossi, David; Nascetti, Giuseppe; Sabetta, Letizia Abstract: To assess riparian influences on lake functioning and develop simple tools for lake health monitoring, the association of remotely-sensed riparian factors and water chemistry with the breakdown rate of reed litter was examined in Lake Vico, a volcanic lake in central Italy. The decomposition rate of Phragmites australis was determined as leaf mass loss from litterbags at 6 locations during summer 2000. Water temperature, dissolved oxygen, nitrogen and phosphorus concentrations, pH, conductivity, percent organic matter in sediments and effective fetch were also assessed at each site. Riparian factors (i.e. shoreline complexity, riparian vegetation cover, and distance from shoreline) were estimated from satellite images (Landsat VII). External organic loadings largely explained spatial heterogeneity in lake metabolism. Decomposition was fastest in the northern area of the lake that drained most of the watershed, including a larger portion in wetland area. Rates correlated exponentially with soluble reactive phosphorus (SRP) concentration, and were positively associated with total-P (TP) concentration and organic matter percentage in sediments, which, in turn, were influenced by the riparian-related factors and waveexposure (fetch). A relationship existed between the index of riparian load, RL, which combined the three riparian-related factors, and both decomposition rate and SRP, suggesting that the riparian index is a promising cost-saving tool for monitoring lake function using remotely-sensed data. Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com/ Sun, 31 Dec 2006 23:00:00 GMT http://hdl.handle.net/2067/1764 2006-12-31T23:00:00Z http://hdl.handle.net/2067/1766 Title: Population genetic structure and diversity of the Apennine endemic stream frog, Rana italica – insights on the Pleistocene evolutionary history of the Italian peninsular biota Authors: Canestrelli, Daniele; Cimmaruta, Roberta; Nascetti, Giuseppe Abstract: For most species in the Western Palaearctic region, southern Mediterranean peninsulas have been identified as major Quaternary refugia and hotspots of intraspecific diversity, and thus, as areas of particular relevance for the conservation of the evolutionary potential. We analysed the patterns of geographical variation among 26 populations of the Italian stream frog, using both nuclear (allozymes) and mitochondrial (partial cytochrome b sequences) markers. Phylogenetic, phylogeographical and population genetic analyses suggested that the species survived the last glacial–interglacial cycles in two distinct refugia, one restricted to the tip of the Calabrian peninsula, at the extreme south of the species’ range, the other spanning from central Calabria to central Apennines and showing evidences for further population subdivision therein. Historical demographic tests suggested a significant population expansion from the latter, which most likely began around the last pleniglacial. This expansion would have led to the rapid colonization of the northern Apennines to the north, and to a secondary contact and population admixture with the population from the southern refugium in southern central Calabria. A comparison of the evolutionary history inferred for the Italian stream frog with the data emerging for other codistributed species suggests: (i) the generality of a multiple-refugia scenario for the Italian peninsula, (ii) the possible occurrence of at least one suture zone in southern Italy, and (iii) that for most species, this Pleistocene refugium is not only a hotspot, but also a melting pot of intraspecific genetic diversity. Finally, the conservation implications of these results are also briefly highlighted. Description: L'articolo è disponibile sul sito dell'editore http://onlinelibrary.wiley.com Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2067/1766 2007-12-31T23:00:00Z http://hdl.handle.net/2067/1767 Title: Phylogeography and historical demography of the Italian treefrog, Hyla intermedia, reveals multiple refugia, population expansions and secondary contacts within peninsular Italy Authors: Canestrelli, Daniele; Cimmaruta, Roberta; Nascetti, Giuseppe Abstract: We investigated the geographical patterns of genetic diversity in the Italian treefrog through sequence analysis of a mitochondrial cytochrome b gene fragment. Three main mitochondrial lineages were identified, distributed in northern, central and southern Italy, respectively. Their divergence appears indicative of a split time largely predating Late Pleistocene climatic oscillations, and syntopy between them was only observed in the geographically intermediate populations. The historical demographic reconstructions suggest that in both northern and central Italy, an expansion occurred during the last major glacial phase, when a vast widening of the lowland habitats followed the glaciation-induced fall of the sea level. Instead, in southern Italy an expansion event likely followed the end of the last glaciation, although the inference of expansion appears less reliable for the southern clade than for the others. Within this geographical area, a sharp phylogeographic discontinuity separated peninsular from Sicilian populations, and the overall pattern of diversity suggests that the latter derived from a recent colonization of the island, probably through a Late Pleistocene land bridge. Phylogenetic, phylogeographic and historical demographic analyses thus concur in delineating a scenario of multiple refugia, with four groups of populations which survived the last glacial–interglacial cycles in at least three distinct refugia arranged along peninsular Italy, and have recently come into contact following range expansions. Therefore, these results support the hypothesis that a plethora of microevolutionary processes, rather than the prolonged stability of populations, were mainly responsible for shaping the patterns of diversity within this major biodiversity hotspot. Description: L'articolo è disponibile sul sito dell'editore http://onlinelibrary.wiley.com Sun, 31 Dec 2006 23:00:00 GMT http://hdl.handle.net/2067/1767 2006-12-31T23:00:00Z