Vipera berus (Linnaeus, 1758) is the terrestrial snake showing the widest distribution in the world, occuring from Great Britain, France and Northern Italy to the Sakhalin Island and North Korea (Nilson, 1980; Saint Girons, 1980; Nilson... more
Vipera berus (Linnaeus, 1758) is the terrestrial snake showing the widest distribution in the world, occuring from Great Britain, France and Northern Italy to the Sakhalin Island and North Korea (Nilson, 1980; Saint Girons, 1980; Nilson et al., 1994; Nilson & Andren, 1997a). However, adders do not occur uniformly over their distribution area, but are scattered in several isolated populations (Nilson & Andren, 1997a). Frequently, ecological traits of borderline and isolated populations differ from those living in the core area of the distribution range of the species, and might be subjected to higher risks of stochastic extinction and higher differentiation rates (Mayr, 1970). For example, meadow vipers ( Vipera ursinii ) show a highly fragmented distribution, many of isolated groups being different subspecies (Nilson & Andren, 1997b, 2001).
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Research Interests: Physiology, Zoology, Pigmentation, Biology, Medicine, and 12 moreTerritoriality, Testosterone, Color, Aggression, Lizards, Animals, Male, Mating, Body Size, Lizard, Veterinary Sciences, and Seasons
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Research Interests: Evolutionary Biology, Genetics, Geography, Genetic Drift, Molecular Evolution, and 15 moreBiology, Medicine, Coalescent Theory, Italy, Mitochondrial DNA, Maximum Likelihood, Animals, Introgression, Mitochondrial Genome, Genetic variation, Maximum Parsimony, Bayes Theorem, Microsatellite DNA, Likelihood Functions, and Founder Effect
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The throat and belly of both sexes of the common wall lizard Podarcis muralis exhibit a polymorphic coloration with three morphs (white, yellow and red). We documented the occurrence of this polymorphism in 11 populations of northern... more
The throat and belly of both sexes of the common wall lizard Podarcis muralis exhibit a polymorphic coloration with three morphs (white, yellow and red). We documented the occurrence of this polymorphism in 11 populations of northern Italy, and investigated the morphometric features of the three morphs in both sexes. The white morph was more frequent (56.6%), while yellow and red morphs accounted for 28.7 and 14.7% of the lizards, respectively. Moreover, the red morphotype was more frequent among males while the white one was more frequent among females. The occurrence of the three morphs varied microgeographically from populations with a higher proportion of white individuals to those where all morphs were more equally represented. The comparisons of morphometry between morphs did not reveal any significant difference among males, while snout–vent length and head height in females increased from the white-throated to the yellow-throated morph, and from the yellow-throated morph to the red-throated one. Possible functions of this polymorphic coloration are discussed.
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A ten year census was carried out on Rana dalmatina and R. latastei egg masses deposited in 36 reproductive sites in a 10‐hectare area, subject to periodic flooding, on the banks of the Ticino River. The vegetation type surrounding... more
A ten year census was carried out on Rana dalmatina and R. latastei egg masses deposited in 36 reproductive sites in a 10‐hectare area, subject to periodic flooding, on the banks of the Ticino River. The vegetation type surrounding reproductive sites was noted. There were no signs of decline in the populations of either frog species. The number of egg
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Research Interests: Biology, Medicine, Lizards, Female, Animals, and 15 moreMale, Body Condition, Body Size, Physiological Response, Lizard, Captivity, Colour Polymorphism, Indexation, Physical Restraint, Erythrocytes, Biochemistry and cell biology, Blood Parameter, Breeding season, Blood Parameters, and leukocyte Count
We censused feral pigeons (Columba livia) living in Milan, Italy (a 181-km2 area), between July 1999 and February 2000 by means of linear transects to examine population densities in different urban habitats and the relationships between... more
We censused feral pigeons (Columba livia) living in Milan, Italy (a 181-km2 area), between July 1999 and February 2000 by means of linear transects to examine population densities in different urban habitats and the relationships between population density and structural features of buildings. The pigeon population of Milan was 103 650 birds, with an average density of 570/km2. Population density increased significantly from farmland (434 birds/km2) to the suburbs (604 birds/km2) and from the suburbs to the centre of the city (2083 birds/km2). There was a positive relationship between both bird number and flock number and the abundance of buildings constructed before 1936. There were no significant associations between either bird number or flock number and the abundance of buildings when we did not consider date of construction. This indicated active selection of old buildings by feral pigeons.
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Sexual dimorphism in digit length ratios has been reported for humans, a few other mammals, and two bird species. This dimorphism is thought to arise via an interaction between the prenatal exposure of the embryo to sex hormones and the... more
Sexual dimorphism in digit length ratios has been reported for humans, a few other mammals, and two bird species. This dimorphism is thought to arise via an interaction between the prenatal exposure of the embryo to sex hormones and the Hox genes, which are highly conserved among vertebrates and control the development of both the appendices, including fingers and toes, and the urogenital system. In this study, we report on sexual dimorphism in 2D:3D, 2D:4D, and 3D:4D contralateral ratios of the forelimbs in two species of oviparous lizards, the common wall lizard (Podarcis muralis) and the tree skink (Mabuya planifrons), as measured on museum specimens. We found that male P. muralis had a larger 2D:4D ratio on both sides and larger 2D:3D ratio on the left side than females, whereas in M. planifrons, males had lower 2D:3D ratios than females on the left side. The two species show opposite patterns of sexual dimorphism in body size, males being larger than females in P. muralis, and the reverse in M. planifrons, suggesting that interspecific variation of sex differences in digit ratios could be associated with sex-specific growth trajectories. There was a limited evidence for directional asymmetry in digit ratios. Therefore, our findings provide the first evidence that digit ratios are sexually dimorphic in any reptile species and are consistent with the idea that the genetic link between limb development and the urogenital system had been established with the evolution of the earliest terrestrial tetrapods. Importantly, many lizard species with genetic sex determination, including the ones we studied, are oviparous and may represent valuable animal models for experimental tests of the association between prenatal exposure to androgens or estrogens and digit ratios.
Research Interests: Evolutionary Biology, Biology, Medicine, Sexual dimorphism, Biological Sciences, and 15 moreLizards, Female, Animals, Male, Reptilia, Lizard, Behavioral Animal Models, Sex Steroids, Oviparity, Sex Differentiation, Species Specificity, Bone and Bones, Sex Characteristics, bone development, and Medical and Health Sciences
In the current paper we show the results obtained using standard and banding staining methods (Ag-NOR-, CMA3-, C-banding and sequential colorations (or Alu I digestions) + CMA3 + DAPI) in specimens of Cerastes vipera, Vipera aspis, V.... more
In the current paper we show the results obtained using standard and banding staining methods (Ag-NOR-, CMA3-, C-banding and sequential colorations (or Alu I digestions) + CMA3 + DAPI) in specimens of Cerastes vipera, Vipera aspis, V. atra, and V. hugyi. Cerastes vipera presented chromosomal characters, primitive in snakes, as a karyotype of 2n = 36 chromosomes, with 16 biarmed macrochromosomes and 20 microchromosomes, NORs on one microchromosome pair and absence of cytologically evident sex chromosomes, at least with the methods used. The three taxa of Vipera studied showed chromosomal characters either derived, or primitive or at an initial stage of differentiation. All three species showed a karyotype (derived) of 2n = 42 chromosomes with 22 macro- and 20 micro-chromosomes; they all showed NORs on one micro-chromosome pair and presented Z and W chromosomes at an initial stage of differentiation. Sexchromosomes Z and W, were in fact homomorphic, but the former was near all euchrom...
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The phylogeography of the colubrid snake Hierophis viridiflavus was estimated using ND4 mtDNA sequences and a fragment of the nuclear marker β-fibrinogen intron 7. This species has a wide distribution across the Mediterranean region, and... more
The phylogeography of the colubrid snake Hierophis viridiflavus was estimated using ND4 mtDNA sequences and a fragment of the nuclear marker β-fibrinogen intron 7. This species has a wide distribution across the Mediterranean region, and is characterized by three distinct colour patterns (“viridiflavus”, abundistic, and melanic-melanotic) with a quite well defined geographic distribution. The “viridiflavus” pattern occurs in the northwestern and central areas of the species' range, the abundistic pattern is typical of the individuals from Corsica and Sardinia, and the melanic-melanotic coloration is present in northeastern and southern Italy, and Sicily. A total of 42 individuals from most of the species' range (including Pyrenees, central France, Italian Peninsula, Corsica, Sardinia and Sicily) were analyzed. Results support the existence of two different mtDNA lineages, one from Spain, France, Corsica, Sardinia, and continental Italy mainly west of the Apennines, and anoth...
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Permanent colour polymorphism in lizards is maintained by complex interactions between environmental pressures and physiological traits (such as immune responsiveness) that differ among morphs. In this study we investigated whether T-cell... more
Permanent colour polymorphism in lizards is maintained by complex interactions between environmental pressures and physiological traits (such as immune responsiveness) that differ among morphs. In this study we investigated whether T-cell mediated immune response vary among male colour morphs in the trimorphic (white, yellow and red) common wall lizard, Podarcis muralis. We found that yellow males showed a lower immune response compared to both red and white males, whose responses were similar. Thus, immune responsiveness is morph-specific in male common wall lizards, suggesting that this physiological trait could play an important role in maintaining colour polymorphism in this species. Moreover, immune responsiveness significantly increased with increasing male size, irrespective of colour morph, indicating that it could be regarded as a condition-dependent trait.
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Repatriations and translocations are among the most frequent actions deployed for conservation of amphibians all over the world. However, very few studies have analysed the effectiveness of these actions. The aims of this study were i) to... more
Repatriations and translocations are among the most frequent actions deployed for conservation of amphibians all over the world. However, very few studies have analysed the effectiveness of these actions. The aims of this study were i) to measure the success of repatriations of Rana latastei carried out within a conservation project in Lombardy (Northern Italy) from 1999 to 2001, and ii) to analyse how the environmental factors affected repatriation success. Eighteen ponds were surveyed from February to April 2006, for an overall of 45 field surveys. Each pond was carefully checked for frogs and egg masses. We classified each pond as newly excavated or pre-existing according to habitat management actions and we measured 16 variables concerning micro- and macro-habitat characteristics, human disturbance and presence of predators. Rana latastei was found in 33.3% of monitored sites and the repatriation outcome of tadpole release did not differ between newly excavated and non managed p...
Research Interests: Zoology, Conservation, Biology, Endangered Species, Amphibia, and 3 moreHabitat, Repatriation, and Woodland
Photographic identification is a promising marking technique alternative to the toe-clipping, since it is completely harmless, cheap, and it allows long time identification of individuals. Its application to ecological studies is mainly... more
Photographic identification is a promising marking technique alternative to the toe-clipping, since it is completely harmless, cheap, and it allows long time identification of individuals. Its application to ecological studies is mainly limited by the time consuming to compare pictures within large datasets and the huge variation of ornamentation patterns among different species, which prevent the possibility that a single algorithm can effectively work for more than few species. Scales of Reptiles offer an effective alternative to ornamentations for computer aided identification procedures, since both shape and size of scales are unique to each individual, thus acting as a fingerprint like ornamentation patterns do. We used the Interactive Individual Identification System (I3S) software to assess whether different individuals of two species of European lizards (Podarcis muralis and Lacerta bilineata) can be reliably photographically identified using the pattern of the intersections...
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Interspecific competition in contact areas is a major topic in ecological studies. A number of studies were carried out on European vipers, focusing on contact areas between two or three species characterized as appropriate by ecological... more
Interspecific competition in contact areas is a major topic in ecological studies. A number of studies were carried out on European vipers, focusing on contact areas between two or three species characterized as appropriate by ecological needs more or less similar. The aim of this study is to extend the analysis of this topic to the case of Vipera aspis and V. berus in an alpine area of northern Italy, by comparing suitability models to verify which ecological factors affect their occurrence and to assess a possible niche separation. Potential distribution was modelled using the maximum entropy method, using six non-correlated ecogeographical variables as predictors. The models fitted well for both species (mean AUC = 0.926; 87.4% of testing data correctly classified). The most informative variables were: habitat, altitude and solar radiation for the asp viper; altitude and habitat for the adder. Deciduous woods, meadows and urban areas had a positive effect on V. aspis distribution...