Mario Lo Valvo

Post-Messinian evolutionary relationships across the Sicilian channel: mitochondrial and nuclear markers link a new green toad from Sicily to African relatives.

BackgroundLittle attention has been paid to the consequences of the last landbridge between Africa and Sicily on Mediterranean biogeography. Previous paleontological and scarce molecular data suggest possible faunal exchange later than the well-documented landbridge in the Messinian (5.3 My); however, a possible African origin of recent terrestrial Sicilian fauna has not been thoroughly tested with molecular methods. To gain insight into the phylogeography of the region, we examine two mitochondrial and two nuclear markers (one is a newly adapted intron marker) in green toads (Bufo viridis subgroup) across that sea barrier, the Strait of Sicily.ResultsExtensive sampling throughout the western Mediterranean and North Africa revealed a deep sister relationship between Sicilian (Bufo siculus n.sp.) and African green toads (B. boulengeri) on the mitochondrial and nuclear level. Divergence times estimated under a Bayesian-coalescence framework (mtDNA control region and 16S rRNA) range from the Middle Pliocene (3.6 My) to Pleistocene (0.16 My) with an average (1.83 to 2.0 My) around the Pliocene/Pleistocene boundary, suggesting possible land connections younger than the Messinian (5.3 My). We describe green toads from Sicily and some surrounding islands as a new endemic species (Bufo siculus). Bufo balearicus occurs on some western Mediterranean islands (Corsica, Sardinia, Mallorca, and Menorca) and the Apennine Peninsula, and is well differentiated on the mitochondrial and nuclear level from B. siculus as well as from B. viridis (Laurenti), whose haplotype group reaches northeastern Italy, north of the Po River. Detection of Calabrian B. balearicus haplotypes in northeastern Sicily suggests recent invasion. Our data agree with paleogeographic and fossil data, which suggest long Plio-Pleistocene isolation of Sicily and episodic Pleistocene faunal exchange across the Strait of Messina. It remains unknown whether both species (B. balearicus, B. siculus) occur in sympatry in northern Sicily.ConclusionOur findings on green toads give the first combined mitochondrial and nuclear sequence evidence for a phylogeographic connection across the Strait of Sicily in terrestrial vertebrates. These relationships may have implications for comparative phylogeographic research on other terrestrial animals co-occurring in North Africa and Sicily.

Can the introduction of Xenopus laevis affect native amphibian populations? Reduction of reproductive occurrence in presence of the invasive species

Biological invasions are regarded as a form of global change and potential cause of biodiversity loss. Xenopus laevis is an anuran amphibian native to sub-Saharan Africa with strong invasive capacity, especially in geographic regions with a Mediterranean climate. In spite of the worldwide diffusion of X. laevis, the effective impact on local ecosystems and native amphibian populations is poorly quantified. A large population of X. laevis occurs in Sicily and our main aim of this work was to assess the consequences of introduction of this alien species on local amphibian populations. In this study we compare the occurrence of reproduction of native amphibians in ponds with and without X. laevis, and before and after the alien colonization. The results of our study shows that, when X. laevis establishes a conspicuous population in a pond system, the populations of Discoglossus pictus, Hyla intermedia and Pelophylax synklepton esculentus show clear signs of distress and the occurrence of reproduction of these native amphibians collapses. In contrast, the populations of Bufo bufo do not appear to be affected by the alien species. Since the Sicilian population of X. laevis shows a strong dispersal capacity, proportionate and quick interventions become necessary to bound the detriment to the Sicilian amphibians populations.

Biometrical and Biological Considerations on the Cory’s Shearwater Calonectris Diomedea

Today the Mediterranean distribution of Cory’s Shearwaters is believed to be well known. New colonies may be discovered, but certainly the largest ones are known. Many data were published during the last ten years and we believe to have a satisfactory knowledge of their biology, though some problems, as the winter movements of each population, the first breeding age and the ratio immatures/adults are still to be examined carefully.

Differences in gene flow in a twofold secondary contact zone of pond turtles in southern Italy (Testudines: Emydidae:Emys orbicularis galloitalica,E. o. hellenica,E. trinacris)

Using virtually range‐wide sampling for three pond turtle taxa (Emys orbicularis galloitalica, E. o. hellenica, E. trinacris), we analyse gene flow across their southern Italian contact zone. Based on population genetic analyses of 15 highly polymorphic microsatellite loci and a mitochondrial marker, we show that the general genetic pattern matches well with the current taxon delimitation. Yet, single individuals with conflicting genetic identity suggest translocation of turtles by humans. In addition, we identify in south‐western France and the vicinity of Rome populations being heavily impacted by introduced turtles. Cline analyses reveal that the major genetic break between E. o. galloitalica and E. o. hellenica corresponds well with the currently accepted intergradation zone in southern Italy. However, introgression is largely unidirectional from E. o. galloitalica into E. o. hellenica. In the distribution range of the latter subspecies, genetic footprints of E. o. galloitalica are evident along most of the Italian east coast. Our results corroborate that E. o. galloitalica was introduced long ago in Corsica and Sardinia and naturalized there. Gene flow between E. orbicularis and E. trinacris is negligible, with the Strait of Messina matching well with the narrow cline centre between the two species. This contrasts with other Mediterranean freshwater turtle species with extensive transoceanic gene flow. Compared to the two subspecies of E. orbicularis, the Sicilian E. trinacris shows an unexpectedly strong population structuring, a finding also of some relevance for conservation. The differences between the two taxon pairs E. orbicularis/E. trinacris and E. o. galloitalica/E. o. hellenica support their current taxonomic classification and make them attractive objects for follow‐up studies to elucidate the underlying mechanisms of speciation by comparing their properties.

Adaptive plasticity of blue tits (Parus caeruleus) and great tits (Parus major) breeding in natural and semi-natural insular habitats

Abstract The breeding performance and foraging of blue and great tits, and the abundance of arthropods living on the trees of an oak‐wood and of a coniferous reafforestation were studied in Sicily, in order to: 1) compare breeding parameters in natural and semi‐natural habitats within the same area; 2) estimate the degree of overlap in peak resource and peak demand of young tits, and the overlap of nestling diet of the two species in the two habitats. Both species had earlier laying dates, laid more eggs and raised more fledglings in the oakwood than in the reafforestation; they achieved the same fledging success within the same habitat type. These differences are probably due to the earlier and higher food peak in oak compared to pine. Food brought to the nestlings differed between habitats and between species: blue tits always brought small prey from a limited number of taxa, while great tits changed both prey taxa and size depending on habitat. The more flexible food of the great tit is in line with the smaller reduction in number of fledglings in pine reafforestation compared to oak‐wood. It is suggested that tits have developed a mechanism to lay eggs at different dates in accordance with the habitat resource where adults catch prey for nestlings. Finally, mean clutch sizes of blue tits between habitats were well correlated, but the process seemed different in the great tit. Significant correlation was indeed detected between the proportion of great tits breeding in oakwood and the difference in the clutch size between the habitats. This suggests that more great tits settled in oakwood in years when conditions were more suitable to produce bigger clutches.

Sexing Adult Cory's Shearwater by Discriminant Analysis of Body Measurements on Linosa Island (Sicilian Channel), Italy

-Males and females of many avian species may show no plumage dimorphism, but often can be sexed by differences in body measurements. Sex determination of many Corys Shearwaters Calonectris diomedea, was possible by multiplying bill length by bill depth. In this study, discriminant analysis of six measurements (bill length, bill depth, wing, tail, tarsus and mass) was performed on Corys Shearwaters breeding on Linosa Island (Sicilian Channel), Italy and the efficiency of sex determination was compared with the univariate method. Results show the advantages of the discriminant functions. Bill depth is the best parameter (up to 92% correct classification), followed by mass (84% correct classification); using mass is simple and causes less disturbance to the birds. Received 10 August 2000, accepted 2 February 2001.

Homing of Cory's shearwaters (Calonectris diomedea) carrying magnets

Abstract Corys shearwaters, equipped with magnets on their bodies and wings, were released far from their nesting‐place. The homing performances of experimental specimens did not differ from those of controls. The results do not support the suggestion that magnetic information plays an essential role in the homing of Corys shearwaters.

Cytokine components and mucosal immunity in the oviduct of Xenopus laevis (amphibia, pipidae)

Most studies on the mucosal immunity in female reproductive tissues have been performed in mammals. In all species, apart from their reproductive strategies, immunity in the genital mucosa is required to defend the host against luminal pathogens. In this study we investigated the role of the innate immunity of the oviductal mucosa of Xenopus laevis, an amphibian characterized by external fertilization. In particular we examined the expression and localization of Interleukin-1β (IL1B), Macrophage migration inhibitory factor (MIF) and Interleukin-1 receptor type 1 (IL1R1) in different oviductal portions including an upper glandular region, an intermediate and a lower aglandular region (the ovisac). Tissues were examined by immunohistochemistry and western blot using polyclonal antibodies against human molecules. IL1B, MIF and IL1R1 were all shown in the three oviductal regions examined, albeit with a general increase towards the external environment. A substantial difference among the cytokine components was also observed mainly in the epithelium of the glandular and intermediate regions. Specifically, all three molecules were expressed by the luminal ciliated cells while only IL1R1 was present in the unciliated cells at the bottom of the epithelial ingrowths. The expression of IL1R1 in these cells appeared as a continuous layer separating the epithelium from the underlying tissues. While supporting the role of the innate immune system for hosts defense against pathogens, the peculiar distribution of the cytokine components in the oviduct of X. laevis suggests novel immunologic strategies useful to assure gland secretion essential for egg formation and fertilization.

GENETIC VARIABILITY AND TAXONOMICAL CONSIDERATIONS ABOUT SIX SPECIES OF EUROPEAN CARDUELINE FINCHES (AVES, PASSERIFORMES)

Abstract Electrophoretic patterns of seven enzyme systems and two nonenzymatic proteins, albumin and haemoglobin, representing 13 loci, have been investigated in six species of cardueline finches with Palearctic distribution. A new locus, SOD-3, has been characterized in this subfamily. The two nonenzymatic proteins turned out to be the best genetic markers. From the analysis of the genetic distances it emerges that the mean values between species are higher than those reported for other groups of birds. However, the same results were obtained for other species of the same subfamily native to North America. In both cases this result is probably due to a classification that disagrees with the real cardueline phylogeny. In the present study, the attribution of the Greenfinch to the genus Carduelis raises the mean value of distance between species.

Bird communities on Mount Etna (Sicily, Italy)

Abstract Mount Etna contains a mosaic of habitats that maintain a rich bird fauna. Between 1981 and 1986 we detected 77 breeding bird species. At the lowest altitudes, the shrubby maquis and the oak woods harbour high populations of Mediterranean species. Above 1000 m dominant conifers (Pinus laricio) contain fewer species with lower diversity in even‐aged stands, but with higher values in the uneven‐aged conifer stands mixed with birch trees (Betula aetnensis). Forest edges yield the highest evenness and richness of the bird communities of Etna, while high‐altitude scrub contains the fewest number of species. Both forest edges and high altitude scrub har bour the highest number of species restricted to these habitat types. These data could be useful in the management of the Regional Park of Etna.