1,721,001 research outputs found
Integrating genetic and parasitological approaches in the frame of multidisciplinary fish stock analysis
No full textFisheries and gene conservation: the case of swordfish and bluefin tuna in the Mediterranean sea.
No full textStruttura genetica e gestione del tonno rosso e dell’alalunga nel Mediterraneo. Genetic structure and management of bluefin and albacore tuna in the Mediterranean Sea.
No full textMolecular taxonomy of European Plethodontid salamanders (genus Hydromantes).
No full textGenetic variation of 33 enzyme loci was analysed electrophoretically in 32 populations of the plethodontid genus Hydromantes from southern France, northern and central Italy, and Sardinia. Eight taxa were recognized, included in three groups: from the mainland, eastern Sardinia, and south-western Sardinia, respectively. In the mainland area, two semispecies were detected: H. italicus and H. ambrosii (sensu stricto), as well as a third species: H. strinatii (combinatio nova), previously included within H. ambrosii. Eastern Sardinian populations correspond genetically to three species: H. flavus, H. supramontis, and H. imperialis. In south-western Sardinia, two genetically differentiated but morphologically very similar groups were found within H. genei, whose specific status remains doubtful. The distinctness of a number of subspecific taxa (H. italicus gormani, H. i. ligusticus, H. i. argentatus, H. i. bonzanoi, H. genei funereus), is not supported by genetic evidence. Data from two contact zones in Italy indicate that taxa showing comparable levels of genetic differentiation (i.e., H. italicus-H. ambrosii s. s. and H. ambrosii s. s.-H. strinatii, both pairs with Nei's D about 0.4) have not reached the same level of reproductive isolation. On the basis of available data, attempts are made: (1) to interpret the present pattern of geographic distribution of European Hydromantes studied; (2) to explain their genetic relationship
Ecological parapatry and competition in two sibling species of European plethodontid salamanders.
No full textThe analysis of a zone of parapatric contact between the European plethodontid salamanders Speleomantes ambrosii and Speleomantes strinatii in northwestern Italy (Liguria) has shown that no syntopic populations exist in the area. The spatial distributions of both species and their relationships with the main environmental parameters has been investigated at two different scales.
At a larger scale, a vegetation survey has revealed that two main vegetation types exist in the contact zone, representing different sets of environmental conditions. The two species are distributed according to the observed vegetationalclimatic patches, with S. strinatii in the more mesic environment and S. ambrosii in the more xeric, and hence less suitable, patches. At a smaller scale, a field experiment artificially created a syntopy, putting together specimens of both species in the same micro-environment. This allowed the study of the spatial distribution of the two species within the environmental micro-patches observed in the caves that Speleomantes use as retreats. S. ambrosii was again found mainly in the micro-patches that were less effective as refuges, while S. strinatii occupied the patches with steady favourable environmental conditions and abundant prey. The comparison of the two sets of results obtained suggests that the two species compete for cover (i.e., a micro-habitat providing high humidity, low temperature and prey availability even during the dry and hot Mediterranean summer). S. strinatii would be the superior competitor, able to confine S. ambrosii in the less suitable environment at both scales
Parapatria e competizione in pletodontidi del genere Hydromantes. Parapatry and competition in Plethodontid salamanders.
No full textMetodo di stima della fragilita’ intrinseca di habitats boschivi nei bacini di drenaggio di laghi vulcanici
No full textL’integrazione dell’ecologia ecosistemica con l’ecologia del paesaggio consentirà spiegazioni meccanicistiche di molti dei patterns osservati nei paesaggi. La propagazione delle perturbazioni è un esempio di come le caratteristiche strutturali e funzionali degli ecosistemi siano influenzate dall’eterogeneità spaziale del paesaggio. In questa ricerca si testa l’ipotesi di una stretta relazione tra eterogeneità ambientale del paesaggio o dei suoi sottoinsiemi e la probabilità di variazioni temporali dei
micropatches più omogenei. Parti di paesaggio sono state delimitate sulla base della varianza spaziale dell’indice NDVI in pixel di immagini satellitari Landsat riferite a tre anni 1987, 1992, 2000. La variazione temporale degli stessi pixel è stata stimata con la tecnica della Change Detection tramite il confronto delle immagini 1987, 1992, 2000. Lo studio ha evidenziato
che le aree più omogenee sono quelle che hanno subito maggiori cambiamenti nel tempo. Si discute questa relazione suggerendo che l’omogeneità può essere considerata una misura della fragilità intrinseca, non altrimenti misurabile, degli habitats relativamente a disturbi i cui effetti possono subire propagazioni
First Speleological and Biological Characterization of a Submerged Cave of the Tremiti Archipelago Geomorphosite (Adriatic Sea)
No full textThe Tremiti Islands Archipelago is located in the Central-Southern Adriatic Sea and is characterized
by a strong karst activity. Due to their landscape, geological, hydrological, archaeological,
and historical value, Tremiti Islands are considered a geomorphosite. We carried out a preliminary,
non-destructive survey by studying the speleological and biological features of the submerged sea
cave Elle, located at Cala Sorrentino (Capraia Island), representing an EU Natura 2000 Priority Habitat.
Topographic (perimeter length, width, height, GPS location, depth) and hydrological parameters
(temperature, dissolved oxygen, pH, irradiance, water movement) were measured and its map was
produced, based on morphological measurements and biological evidence. Species composition
and biotic cover were investigated by image analysis. The benthic community was dominated by
poriferans, together with remarkable assemblages of scleractinians and polychaete serpulids and
clearly reflected the sharp light and hydrological gradients from the entrance to the cave bottom.
Furthermore, different phases were hypothesized for the genesis of the cave during sea regression
and flooding periods. To be signaled is the record of Petrobiona massiliana, a sponge was protected
under both Barcelona and Bern Convention and of some individuals of polychaete Serpulinae, which
are still under description
Parasitic infestation by larval helminths in Antarctic fish: pathological changes and impact on the host body condition index
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