Claudia Corti

Determination of genetic diversity within the insular lizard Podarcis tiliguerta using mtDNA sequence data, with a reassessment of the phylogeny of Podarcis

Despite being the predominant reptile group in Southern Europe, the taxonomy of Podarcis Wall lizards is both complex and unstable. Recent attempts to estimate a phylogeny for the genus using molecular methods have been largely unsuccessful, with many poorly resolved nodes and widely different estimates from different studies (Harris and Arnold, 1999; Oliverio et al., 2000; Poulakakis et al., 2003). One possible reason for this is that presently accepted forms may well be species complexes — Podarcis hispanica∗ (Steindachner, 1879) contains several highly genetically distinct lineages all of which may deserve species status based on mitochondrial (Harris and Sa-Sousa, 2002; Harris et al., 2002) and protein electrophoretic data (Pinho et al., 2003). Podarcis erhardii (Bedriaga, 1882) is also probably a species complex (Poulakakis et al., 2003), Podarcis sicula and Podarcis melisellensis contain considerable genetic diversity (Podnar et al., 2004, 2005) although Podarcis lilfordi (Günter,

Mitochondrial phylogeography, contact zones and taxonomy of grass snakes (Natrix natrix, N. megalocephala)

Grass snakes (Natrix natrix) represent one of the most widely distributed snake species of the Palaearctic region, ranging from the North African Maghreb region and the Iberian Peninsula through most of Europe and western Asia eastward to the region of Lake Baikal in Central Asia. Within N. natrix, up to 14 distinct subspecies are regarded as valid. In addition, some authors recognize big‐headed grass snakes from western Transcaucasia as a distinct species, N. megalocephala. Based on phylogenetic analyses of a 1984‐bp‐long alignment of mtDNA sequences (ND4+tRNAs, cyt b) of 410 grass snakes, a nearly range‐wide phylogeography is presented for both species. Within N. natrix, 16 terminal mitochondrial clades were identified, most of which conflict with morphologically defined subspecies. These 16 clades correspond to three more inclusive clades from (i) the Iberian Peninsula plus North Africa, (ii) East Europe and Asia and (iii) West Europe including Corso‐Sardinia, the Apennine Peninsula and Sicily. Hypotheses regarding glacial refugia and postglacial range expansions are presented. Refugia were most likely located in each of the southern European peninsulas, Corso‐Sardinia, North Africa, Anatolia and the neighbouring Near and Middle East, where the greatest extant genetic diversity occurs. Multiple distinct microrefugia are inferred for continental Italy plus Sicily, the Balkan Peninsula, Anatolia and the Near and Middle East. Holocene range expansions led to the colonization of more northerly regions and the formation of secondary contact zones. Western Europe was invaded from a refuge within southern France, while Central Europe was reached by two distinct range expansions from the Balkan Peninsula. In Central Europe, there are two contact zones of three distinct mitochondrial clades, and one of these contact zones was theretofore completely unknown. Another contact zone is hypothesized for Eastern Europe, which was colonized, like north‐western Asia, from the Caucasus region. Further contact zones were identified for southern Italy, the Balkans and Transcaucasia. In agreement with previous studies using morphological characters and allozymes, there is no evidence for the distinctiveness of N. megalocephala. Therefore, N. megalocephala is synonymized with N. natrix.

Using faecal samples in lizard dietary studies

While the use of faecal pellets is widely accepted as a primary methodological source of data for dietary studies, a recent paper advocated for the use of gut contents. This was due to the fact that faecal samples would give biased results of the diet of arthropod predators, due to a lower representation of soft-bodied prey in faecal pellets. To test this assumption, we compared the spring diet of several populations of two insular lizards from the Balearic Islands (Spain), Podarcis lilfordi and Podarcis pityusensis, using both faecal pellets and gut contents. Our results do not support the supposed bias of dietary analyses based on faecal pellets. Indeed, soft-bodied prey and particularly insect larvae are often equally represented in faecal pellets and gut contents. Alternatively, soft bodied prey are represented in different proportions in gut contents and faecal pellets, but in some cases with higher proportions being observed in the gut contents, and in other cases with higher proportions in faecal samples. We conclude that faecal pellets can be a reliable source of information for dietary studies.

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.

Determining environmental minimum requirements for functions provided by agro-ecosystems

The definition of meaningful and realistic targets is the key element in the development of agri-environmental measures to improve the present situation of agricultural landscapes both from ecological and socio-economic points of view. Such targets should be based on a system of reference values that consider ecological thresholds and the carrying capacity of ecosystems and landscapes as well as the demands and necessities of human society in a specific area. In this way, so-called Environmental Minimum Requirements (EMR) can be prescribed for each indicator selected. With the help of EMR it is possible to envisage the minimum values to be matched by the state indicators, below which the particular environmental function becomes jeopardised at the level of the area under consideration. Thus, the definition of EMR is the crucial step to bridge scientific analyses of the ecological state with socio-economic and political evaluations. In examples of the EU-project AEMBAC, various approaches of determining EMR for indicators in the field of biodiversity, soil, water and ‘landscape’ are described. EMR can be classified according to their sources, spatial differentiation, scale and temporal validity. EMR values can vary between countries and local levels. Admittedly, the definition of EMR should take account of value-free scientific facts but an evaluation step is needed as well as the orientation towards human targets to avoid naturalistic fallacy.

Aspects of population ecology of Testudo hermanni hermanni from Asinara Island, NW Sardinia (Italy, Western Mediterranean Sea): preliminary data

Hermanns tortoise ( Testudo hermanni Gmelin) of the Island of Asinara (NW Sardinia, Italy) has been studied during a period of four seasons. This population consisted of several individuals of large body size, some of them being amongst the largest known for this species. Bony shells of males were commonly found on this island, while the same was not true for female bony shells. Although wild boars ( Sus scrofa ) are potential large sized predators for tortoises, the analysis of carapace morphology did not reveal injuries signs due to bites. Male tortoises could die due to up-turning, as the result of male-male combats during the mating season, to possible hyperthermia when upturned, and to predation carried out by birds particularly when upturned. Estimated density was 4.88 individuals ha -1 , which was similar to that of conspecifics from other areas studied so far.

Is the imperilled spur-thighed tortoise (Testudo graeca) native in Sardinia? Implications from population genetics and for conservation

Using mtDNA sequences and 12 microsatellite loci, we compare populations of Testudo graeca from Sardinia and North Africa. The observed pattern of almost no differentiation combined with reduced variation in the Sardinian population is consistent with introduction in prehistoric or historic times from what is now Tunisia and neighbouring Algeria. Furthermore, in the light of the recently published recommendation to eradicate the non-native T. graeca from Italy, we review recent studies on the archaeological and fossil record, on the phylogeography and population genetics of the three other chelonian species occurring in Sardinia (Emys orbicularis, T. hermanni, T. marginata). We conclude that the extant Sardinian populations of all four species are not native. However, they are and should be safeguarded under EC law (Council Regulation No 338/97 on the Protection of Species of Wild Fauna and Flora; Flora Fauna Habitat Directive: Appendix IV, Art. 12) because they serve as a back-up for the declining mainland populations. Moreover, these populations constitute an important part of the human-shaped natural heritage of the Mediterranean.

Phylogenetic relationships of Sardinian cave salamanders, genus Hydromantes, based on mitochondrial and nuclear DNA sequence data

The Tyrrhenian island of Sardinia is known for its high level of endemism. Beside the importance of this island as a refuge during the last glaciations, little is known about the origin and relationships of Sardinian species. Therefore, in an effort to resolve these relationships, in the current study we extended the existing dataset considerably by adding two nuclear genes and additional mitochondrial sequence data, as well as greatly extend the number of Sardinian populations represented in the dataset from eight to 16 populations.

Different habitats, different pressures? Analysis of escape behaviour and ectoparasite load in Podarcis sicula (Lacertidae) populations in different agricultural habitats

Human agricultural activities can deeply alter the environment thus provoking major impacts on a variety of organisms. Agricultural habitats however can be very different from one another in terms of habitat structure and management intensity, presenting varying pressures and/or benefits for different species. Agro-ecosystems can have opposing effects on reptiles and in some circumstances the presence of a species can even been enhanced by agricultural practices. We focused our study on Podarcis sicula, a relatively widespread lacertid lizard commonly present in agro-environments in Italy. We examined escape behaviour, caudal autotomy rates and ectoparasite load (tick infestation) in populations living in two different land uses, olive tree plantations and vineyards. All three aspects seemed to be deeply influenced by habitat structure. Predation pressure, as evaluated by tail break frequency, was lower in olive tree plantations, the most structurally complex habitats. In this type of habitat lizard escape behaviour was characterised by a clear preference for olive trees as refuges: individuals ran farther distances on average to reach the trees and hid inside them for a relatively long time. In vineyards, on the contrary, a less clear escape strategy was observed, showing a use of more temporary refuges. Also tick (Ixodes ricinus) infestation differed among land uses, being higher in olive tree plantations, probably in relation to vegetation cover features. Differences were found also between managements (with a higher tick load in traditional cultivations) and sexes, with males being more parasitized.

Assessing the Spatial Scale Effect of Anthropogenic Factors on Species Distribution

Patch context is a way to describe the effect that the surroundings exert on a landscape patch. Despite anthropogenic context alteration may affect species distributions by reducing the accessibility to suitable patches, species distribution modelling have rarely accounted for its effects explicitly. We propose a general framework to statistically detect the occurrence and the extent of such a factor, by combining presence-only data, spatial distribution models and information-theoretic model selection procedures. After having established the spatial resolution of the analysis on the basis of the species characteristics, a measure of anthropogenic alteration that can be quantified at increasing distance from each patch has to be defined. Then the distribution of the species is modelled under competing hypotheses: H0, assumes that the distribution is uninfluenced by the anthropogenic variables; H1, assumes the effect of alteration at the species scale (resolution); and H2, H3 … Hn add the effect of context alteration at increasing radii. Models are compared using the Akaike Information Criterion to establish the best hypothesis, and consequently the occurrence (if any) and the spatial scale of the anthropogenic effect. As a study case we analysed the distribution data of two insular lizards (one endemic and one naturalised) using four alternative hypotheses: no alteration (H0), alteration at the species scale (H1), alteration at two context scales (H2 and H3). H2 and H3 performed better than H0 and H1, highlighting the importance of context alteration. H2 performed better than H3, setting the spatial scale of the context at 1 km. The two species respond differently to context alteration, the introduced lizard being more tolerant than the endemic one. The proposed approach supplies reliably and interpretable results, uses easily available data on species distribution, and allows the assessing of the spatial scale at which human disturbance produces the heaviest effects.