Massimo Capula

Comparative ecology in sympatric Podarcis muralis and P. sicula (Reptilia: Lacertidae) from the historical centre of Rome: What about competition and niche segregation in an urban habitat?

Abstract Some aspects of comparative ecology in two sympatric Podarcis species, P. muralis and P. sicula, were studied in an urban park of Rome. Both species preyed on a wide variety of invertebrates, but mainly on insects. Food niche breadth was wider in P. muralis, and this is possibly related to the higher microhabitat heterogeneity of the species in the study area. Food niche overlap was relatively high. Activity patterns (annual cycle, daily activity) were rather similar in the two lacertid lizards. Fecundity did not differ significantly between species, female snout‐vent length and clutch size being positively correlated. At least two clutches per year were detected in each species. In each of the two study sites chosen in the urban park the density of both species did not vary significantly amongst years. Podarcis muralis appeared to be the only species inhabiting humid places with dense vegetation, while P. sicula was numerically more abundant than P. muralis in sunny and dry spots. Although concl...

Comparative Diets of Three Populations of an Aquatic Snake (Natrix tessellata, Colubridae) from Mediterranean Streams with Different Hydric Regimes

Abstract The Dice Snake (Natrix tessellata) is an aquatic colubrid that is known for having a basically piscivorous diet and a female-biased sexual size dimorphism (larger females). The feeding habits of three populations of N. tessellata from Mediterranean streams in central Italy were studied. The three streams differed in terms of their water regimes, one being seasonal and two being perennial. More than 2,000 snake individuals were handled for food items, and 1,200+ prey items were collected. The percent of fed snakes was significantly influenced by the study area and by the interaction term between study area and season (i.e., by the hydric regime). Fishes accounted for over 90% of the snake diets at all study areas, the most common prey species being cyprinids. Overall, the three snake populations had similar taxonomic diet composition. There was a significant ontogenetic change in diets in all populations. There were also significant intersexual differences in prey composition, with the females taking more Scardinius erythrophtalmus fishes and more anurans, and the males more Leuciscus s. muticellus. The various fish species found at the three study areas (15 species) were classified in terms of six independent ecological characteristics in order to investigate what factors make a given prey species suited or not for Dice Snakes. It appeared that N. tessellata selected mainly fish species that were gregarious, small to medium sized, active foraging, diurnal, and not using mud as preferred substratum. We also found that the seasonal desiccation of the stream-bed of one study area caused a shift in the diet composition of these snakes, with males and juveniles being the categories where the seasonal dietary shift was more evident. Males preyed especially on the fishes S. erythrophtalmus and Leuciscus cephalus, and the juveniles preyed upon Leuciscus s. muticellus, whereas in spring their primary prey was Alburnus a. alborella.

Comparative food habits and body size of five populations of Elaphe quatuorlineata : the effects of habitat variation, and the consequences of intersexual body size dimorphism on diet divergence

Abstract The comparative diet and body size of the Four-Lined Snake (Elaphe quatuorlineata), one of the largest and more vulnerable species of snakes in Mediterranean central Italy, were studied in five different habitats. Data given here collated both literature and original data. Overall, females were significantly larger than males but the strength of these differences varied considerably with sample size. Overall, small mammals (almost exclusively rodents) accounted for the main part of the diet (66.7%), followed by birds and their eggs (mainly Passeriformes; 26.4%), and by lizards (6.9%), although the number of eggs in the diet was probably greatly underestimated. In qualitative terms, both sexes fed on the same prey types, but, quantitatively, males and females differed significantly in terms of prey composition; females fed on more birds and fewer lizards than males. Rodents were the most important prey source in most habitat types, although birds were preyed upon slightly more frequently in the wet habitat than rodents, which, nonetheless, still represented a important prey source. Four-Lined Snakes started feeding in early April and continued feeding until early November. The monthly frequency of occurrence of birds in snake stomachs differed significantly from that of small mammals; birds were taken almost exclusively in April and May (and mainly by females), and small mammals were taken all throughout the annual feeding cycle of snakes.

Distribution of genetic variation and taxonomy of insular and mainland populations of the Italian wall lizard, Podarcis sicula

The genetic structure and heterogeneity of Podarcis sicula (Reptilia, Lacertidae) was studied in insular (Pontine Archipelago) and mainland (central and southern Italy) populations by means of allozyme electrophoresis at 20 presumptive gene loci. Genetic variability in the species is low and genetic subdivision is high. The highest values of percent polymorphism and heterozygosity were found in the samples from the southernmost part of Italy (Calabria). The insular samples from the Pontine Archipelago were characterized by loss of alleles and erosion of genetic variability. Population heterogeneity analysis carried out by the estimation of Wrights F-statistics demonstrated substantial genetic differentiation among populations. F-statistics and genetic distance data show that genetic variation is distributed into three population groups. The first group includes the genetically very similar populations from central Italy and the Pontine Archipelago, the second includes the populations from Campania (southern Italy), the third comprises the populations from the southernmost part of the Italian Peninsula (Calabria). Based on the results of the allozyme data, the systematic status of the subspecies of P. sicula occurring in the studied areas is discussed.

Genetic and morphometric evidence of introgression between two species of moles (Insectivora: Talpa europaea and Talpa romana ) in central Italy

Allozyme and morphometric variation was studied in two populations of moles, Talpa europaea and T. romana, in an area of sympatric occurrence (Palazzo, near Assisi, central Italy) located along the known parapatric contact boundary. The electrophoretic analysis revealed 36 moles characterized by a genome of T. europaea, and 29 moles with a genome of T. romana. The extension of the overlap zone was c. 2 km along the north–south direction. Fourteen specimens recognized as T. europaea had an Ada allele typical of T. romana, while two specimens identified as T. romana were characterized by two alleles (at the Adh and Sdh loci) previously found only in T. europaea. The skulls of the specimens with introgressed alleles showed features intermediate between those typical of T. romana and T. europaea. However, the intermediate skull shape of the introgressed specimens did not correspond to an intermediate size between T. romana and T. europaea. The occurrence of individuals with introgressed alleles, and the lack of F1 hybrids or backcrossed individuals suggest that at present free interbreeding between the two species is unlikely, but that hybridization and backcrossing has occurred, probably when the species first came into contact.

Resource partitioning in a Mediterranean lizard community

Abstract Some aspects of community ecology in a lizard assemblage composed of three sympatric and diurnal species (Algyroides fitzingeri, Podarcis tiliguerta, Chalcides ocellatus) were studied in a Mediterranean habitat of central Sardinia. The three lizards were characterized by significantly different mean body size. There was no spatial overlap between the smallest species (A. fitzingeri) and the largest one (C. ocellatus), while there was a certain amount of overlap between P. tiliguerta and each of the other two lizards. The three species preyed on a wide variety of invertebrates, but mainly on insects. Food niche breadth was higher in P. tiliguerta, and this could be related to the higher microhabitat heterogeneity of this lizard in the study area. Food niche overlap was high between Chalcides ocellatus and Podarcis tiliguerta, but low between Algyroides fitzingeri and C. ocellatus. Although further data are required before any firm conclusion can be drawn, the results of this investigation seem to ...

The decline of the Aeolian wall lizard, Podarcis raffonei : causes and conservation proposals

Investigations carried out in the Aeolian Islands (off north-east Sicily) during 1989–99 gathered evidence strongly indicating that the endemic Aeolian wall lizard Podarcis raffonei is close to extinction. Competitive exclusion by the lizard Podarcis sicula , which has been introduced by man, habitat degradation, and possibly reduced genetic variability and inbreeding, were the main causes for the decline of the species. For the Aeolian wall lizard to recover from its threatened status and to prevent further decimation of populations, collection and trade in the species should be prohibited, and an education programme for local people should be promoted. An integrated project involving habitat protection and captive breeding is needed to secure the species in the wild for the future.

Genetic evidence of natural hybridization between Podarcis sicula and Podarcis tiliguerta (Reptilia: Lacertidae)

An allozyme survey revealed instances of natural hybridization between Podarcis sicula and P. tiliguerta from a locality of southern Sardinia. Pure specimens of both species together with some F1 hybrids were found, but no evidence of backcrossing was detected. The hybrid specimens appeared morphologically intermediate between the parent species. The absence of backcrossed individuals indicate that free interbreeding between the two species is unlikely. Hybrids were found in areas of habitat disturbance only.

HIGH GENETIC VARIABILITY IN INSULAR POPULATIONS OF THE LACERTID LIZARD, PODARCIS MURALIS

Abstract Allozyme electrophoresis was used to study genetic variability in Italian insular populations of the ecologically variable lizard Podarcis muralis . To test the theory predicting more genetic variation in mainland than in island populations, polymorphism and heterozygosity also were estimated in mainland populations of P. muralis from Italy, Spain and Austria. The results of this investigation showed that levels of genetic variability in insular populations were significantly higher than those in mainland populations. This is probably because the insular populations inhabit marginal environments characterized by temporal-ecological instability. In these environments high heterozygosity levels can be preserved after colonization events, unless founder populations are so small that bottleneck effects occur.

Geographic variation in the diet composition of a secretive Mediterranean colubrid snake: Coronella girondica from Spain and Italy

Abstract A comparative analysis of the diet of the small‐sized colubrid snake, Coronella girondica, from Spain and Italy was carried out. More than 95% of the prey consumed by Spanish C. girondica had diurnal behaviours, and all the prey were terrestrial dwelling or ‘rupicolous’ species, with no arboreal item being eaten. The same was true also for the Italian specimens. Lizards (mainly lacertids) accounted for the main bulk of the prey spectrums in both the Spanish and Italian samples. However, Italian specimens preyed frequently upon ground arthropods (mainly chilopods), that were not consumed by Spanish specimens. Mean prey size was similar in both the geographic areas. Some ecological implications of the observed patterns are highlighted.