Search results for " Biogeography."
showing 10 items of 61 documents
Primo rinvenimento in Sicilia di Typha laxmannii (Typhaceae)
2011
First record of Typha laxmannii Lepech. (Typhaceae) in Sicily. Typha laxmannii Lepech. (Typhaceae) is here reported, for the first time, in Sicily at Scopello, near Castellammare del Golfo (NW Sicily). This species is compared with the congenerics occurring in the region; dichotomous key and description are also given to make the identification easier.
Genetic diversity in Cytisus aeolicus Guss. (Leguminosae), a rare endemite of the Italian flora
1998
ABSTRACT Cytisus aeolicus Guss, is an endemic plant restricted to the isles of Vulcano, Stromboli and Alicudi in the Aeolian archipelago. All known populations were assayed for genetic variability using enzyme polymorphism. Allozyme variation at 16 loci coding for 10 enzyme systems was examined. The great majority of loci turned out to be monomorphic or fixed heterozygous. The observed genetic depauperation is indicative of historical factors, such as the bottleneck effect associated with migration, and the founder effect in population re-establishment. The low genetic diversity is largely partitioned within rather than among populations, indicating that extant populations have not been est…
Isolation and biodiversity inCytisus villosusPourret (Fabaceae, Genisteae): enzyme polymorphism in disjunct populations
1997
ABSTRACT The genetic diversity of isolated populations of Cytisus villosus has been studied by means of enzyme polymorphism analysis. Two types of isolated populations were studied: “terrestrial islands” in Sicily, and “true islands” in the Aeolian archipelago. In the populations of “true islands” the number of alleles and the heterozygosity are lower than in “terrestrial islands”. Isolation amongst Sicilian populations seems to be more recent than isolation of the Aeolian populations, and may be attributed to climatic changes which occurred during the Holocene and/or to human activities. The disjunction of the Aeolian populations seems much more recent than the origin of the isles themselv…
La Biogeografia della Sicilia: considerazioni conclusive sul XXXVII Congresso della Societa' Italiana di Biogeografia
2011
Biogeographia vol. XXX - 2011 (Pubblicato il 23 dicembre 2011) La Biogeografia della Sicilia La Biogeografia della Siciliaz considerazioni conclusive sul XXXV11 Congresso della Societa Italiana di Biogeografia BRUNO MASSA* VALERIO SBORDON1**, AUGUSTO V1GNATAGL1ANT1*** q‘ Dipartimento Demetra, Universita dzq Palermo; e—maz'[: eruno. massa @unz}ga.z't ** Dzpartimento di Biologia, Uniz/ersita di Roma q Ybr 1/Ergata”; e—mai[:12a1erz'o.5[9ord0ni@uniroma2. it *** Dipartimento di Biologia e Biotecnologie “Charles Darwin”, Universita di Roma qLa Sapienza”; e—mai[: augusto. z2z'gnatag[z'anti@uniroma1.it 11 tema generale del Congresso e stato la Biogeografia della Sicilia, al suo in~ …
THE GARGANO TERRE ROSSE INSULAR FAUNAS: AN OVERVIEW
2010
After forty years from its discovery, the history of the field surveys and of the researches on the fossiliferous deposits on Gargano is briefly reported. The Gargano fauna belongs to the Abruzzo-Apulian Palaeobioprovince (including also Scontrone and Palena, Abruzzo). The fossil assemblage comprehends all the classes of terrestrial vertebrates: Reptilia, Amphibia, Aves and Mammalia. The faunal composition is unbalanced and presents the features of a typical insular endemic fauna. The bulk of the assemblage is composed of small mammals and birds. Based on literature, we report the most characteristic features, phylogenetic relationships, and evolutionary remarks on a list of mammals, focusi…
Land mammal colonisation of islands is a multifactorial product; a critic to the unwise use of models
2011
The colonization of islands by terrestrial mammals has been the topic of a flurry of studies. Contributions normally tend to oversimplify the subject, focusing on specific key factors which are allegedly considered the best to explain why, how and when non volant terrestrial mammals reached islands and which are used to devise models. The subjectivity in the choice of key factors understandably leads to controversy and debate. Insular faunas are the multifactorial result of complex combinations of facts, conditions and processes. Hence, the faunal assemblages of each island should be inquired individually, on a case-by-case basis. Models, by definition, are simplified representations of rea…
Global review of recent taxonomic research into Isoetes (Isoetaceae), with implications for biogeography and conservation
2018
With the advent of cytological analysis, Scanning Electron Microscopy, the recognition of sterile hybrids, improved access to wild populations and increasingly comprehensive molecular investigations, there has been a revolution in Isoetes taxonomy in recent times. The last 40 years have seen an almost 100% increase in the diversity documented during the previous two centuries. Four geographic areas account for over 90% of this diversity: northern-central South America, eastern North America, western Eurasia (including the northern Mediterranean) and South to Tropical Africa. There is a significant global conservation concern for Isoetes, with many taxa being rare (known from one to a handfu…
AMMONOID EVOLUTION TRIGGERED BY PALAEOGEOGRAPHIC CHANGES: ORIGIN OF OXFORDIAN SUBFAMILY PASSENDORFERIINAE (SOUTHERN TETHYS)
2011
The comparison of Middle-Upper Jurassic ammonite successions in SW Sicily (Sciacca) and Iberia shows that, during the Middle Jurassic, besides some typical Mediterranean taxa, in Sicily as well as in the Betic Ranges (S Spain) ammonoid successions contain a higher share of typical Submediterranean taxa of Ammonitina, entirely comparable to those recorded in Epicontinental areas of Eastern Iberia. From middle Oxfordian onwards instead, ammonite successions show a clear taxonomic differentiation, being dominated in Sicily by typically Mediterranean taxa (Passendorferiinae) whilst typical Submeditrerranean groups (Perisphinctinae, Oppeliidae) clearly dominant in the Iberian Range, are testimon…
Factors affecting between-lake variation in the occurrence of epidermal papillomatosis in roach,Rutilus rutilus(L.)
2009
The theory of island biogeography predicts that the probability of a species occupying an island depends on a dynamic equilibrium between extinction and colonization. Epidermal papillomatosis is a disease manifesting as skin tumours on fish. We studied the factors affecting the occurrence of the disease in roach, Rutilus rutilus (L.), in 34 lakes. The results of discrimination analysis suggest that maximum depth, percentage of the drainage area of the lake covered by lakes in the vicinity and altitude best identified diseased lakes. Comparison of diseased and non-diseased lakes revealed that lake area could also be regarded as a variable contributing to the occurrence of the disease. The sa…
Mediterranean island biogeography: Analysis of fern species distribution in the system of islets around Sicily
2011
The aim of this article was to test the way in which geographical factors influence island floras in the Mediterranean basin, using ferns as target organisms, and the islands surrounding Sicily as location. A matrix with presence/absence data concerning fern taxa in the 16 islands studied was compiled. Cluster analysis, principal co-ordinates analysis (PCoA), principal components analysis (PCA) and a Bayesian analysis were performed. For each island, the total number of fern taxa was regressed against three factors: island area, island elevation and isolation. All the analyses pointed to affinities between islands according to their different geological composition, independently from their…