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Alien invasive species are a major threat to amphibians. The red swamp crayfish, Procambarus clarkii, is native of eastern North America but has been introduced worldwide, and can cause dramatic declines of amphibians. We analyzed the distribution of amphibians and of P. clarkii in an area of northern Italy where the crayfish has been recently introduced.We assessed the relationship between wetland features, the distribution of P. clarkii and the richness and structure of amphibian communities. We surveyed 114 wetlands, using a combination of standard methods; we recorded environmental features (size, depth, hydroperiod), and analyzed relationships using generalized additive models, including components taking into account spatial autocorrelation. We found the richest communities in wetlands with intermediate size and hydroperiod. Conversely, P. clarkii was associated to the largest, permanent wetlands. Amphibian communities were significantly nested; wetlands with intermediate size and hydroperiod hosted communities with less gaps than expected by chance. However, two species (Bufo bufo and Salamandra salamandra) were less nested than the other amphibians. Management focusing on relatively small, semipermanent wetlands, that are isolated from the main hydrographic network, may be an effective strategy for amphibian conservation, because these wetlands can have suboptimal features for P. clarkii. Nevertheless, these wetlands are not enough for the conservation of the whole amphibian community, because some species have peculiar requirements.

Aim: Analyses of biogeographical patterns and macroecology of islands require large datasets reporting the occurrence of species. The Mediterranean region is a biodiversity hotspot, which hosts a large number of reptile species and has been the focus of many studies. Nevertheless, comprehensive inventories describing the features and biodiversity of these environments are lacking. We gathered a dataset summarizing data on reptile distribution on islands of the Mediterranean basin and Macaronesia, also including detailed information on the geographical features. Location: Islands from the Mediterranean Basin, the Atlantic Ocean within the Mediterranean biogeographical region, and Macaronesia (Canary and Savage Islands, Azores, Madeira and Cape Verde). Time period: Present. Taxon: Reptiles (squamates and turtles). Methods: Initially, we developed a geographical database describing islands of the study region, then gathered information on reptile occurrences from 757 bibliographical sources, including atlases, published papers and the grey literature. Through a critical review of these sources, we also obtained information on the status of populations (native, island endemic or non-native) and on the reliability of occurrence data. Results: We obtained basic geographical information from 1875 islands covering the whole study region and with a very broad range of geographical features. We gathered >4150 records of reptile occurrence on islands, referring to 198 taxonomic units (species or species complexes); information on population status was available for 84.9% of records. Data are provided as comma-delimited text files. Main conclusions: The database provides a key resource for biogeographical analyses and can also serve as a backbone for conservation studies. The availability of a large database on island features can also be useful for biogeographers working on other taxonomic groups. Nevertheless, more data are required for some geographical areas, in order to ascertain the status (e.g., native vs. non-native) of many populations and to understand the interplay between natural and human-driven processes.

Context: A landscape is defined as a “system of ecosystems” and this is a model in which karst areas can easily be integrated. In karst areas, much of the connectivity between the units of the landscape is underground, with aquifers and caves forming a continuous layered tissue. However, underground environments are among the least studied landscapes on Earth because of limited accessibility and the difficulty of performing surveys. Objectives: The aim of this paper is to provide a conceptual framework for applying principles of landscape ecology to research on karst environments. Methods: By adapting the standard patch-corridor-matrix model to a 3d model, the main issues that need to be addressed were identified. These include identifying the main morphological (surface and underground) karst features; determining the landscape structure through its features, composition, and configuration; and developing adequate indices. Results: The landscape spatial structure of different karst areas influences fundamental ecological functions and biodiversity patterns. Determining how structure, biodiversity, and functions relate reveals important insights into the functioning of karst systems. Emphasizing the provisioning of ecosystem services is essential in supporting the concept that karst regions are vital for human well-being because they host valuable resources and fundamental ecosystem processes. The paper discusses how this framework helps address anthropogenic impacts and conservation issues on karst. Conclusions: The potential of applying a landscape approach to karst systems lies in developing models that provide ecological information relevant to understanding karst systems and understanding their implications for natural resources management.

Accurate measures of species abundance are essential to identify conservation strategies. N-mixture models are increasingly used to estimate abundance on the basis of species counts. In this study we tested whether abundance estimates obtained using N-mixture models provide consistent results with more traditional approaches requiring capture (capture-mark recapture and removal sampling). We focused on endemic, threatened species of amphibians and reptiles in Italy, for which accurate abundance data are needed for conservation assessments: the Lanza’s Alpine salamander Salamandra lanzai, the Ambrosi’s cave salamander Hydromantes ambrosii and the Aeolian wall lizard Podarcis raffonei. In visual counts, detection probability was variable among species, ranging between 0.14 (Alpine salamanders) and 0.60 (cave salamanders). For all the species, abundance estimates obtained using N-mixture models showed limited differences with the ones obtained through capture-mark-recapture or removal sampling. The match was particularly accurate for cave salamanders in sites with limited abundance and for lizards, nevertheless non-incorporating heterogeneity of detection probability increased bias. N-mixture models provide reliable abundance estimates that are comparable with the ones of more traditional approaches, and offer additional advantages such as a smaller sampling effort and no need of manipulating individuals, which in turn reduces the risk of harming animals and spreading diseases.

SCOPUS: ar.j, info:eu-repo/semantics/published

The analysis of biogeographical structure and patterns of endemism are central topics of biogeography, but require exhaustive distribution data. A lack of accurate broad-scale information on the distribution of reptiles has so far limited the analyses of biogeographical structure. Here we analysed the distribution of reptiles within the broad-sense Western Palearctic to assess biogeographical regionalization using phylogenetic and non-phylogenetic approaches, identified areas of endemism and evaluated the environmental factors promoting community uniqueness and endemism. We gathered distributional records from the literature and from the field, mapping the distribution of all the Western Palearctic reptiles on a 1-degree resolution grid. βsimdissimilarity and hierarchical clustering was used to identify bioregions, analysing data both at the species and at the genus level, and considering phylogenetic dissimilarity. Consensus areas of endemism were identified on the basis of the optimality criterion. We then assessed whether biogeographical structure is related to present-day climate, insularity, orography and velocity of climate change during the Late Quaternary. The genus-level analysis identified five main biogeographical regions within the Western Palearctic, in partial agreement with previous proposals, while the species-level analysis identified more bioregions, largely by dividing the ones identified by genera. Phylogenetic bioregions were generally consistent with the non-phylogenetic ones. The strongest community uniqueness was observed in subtropical warm climates with seasonal precipitation and low productivity. We found nine consensus areas of endemism, mostly in regions with limited velocity of Quaternary climate change and warm subtropical climates. The biogeographical structure of Western Palearctic reptiles is comparable to what has been observed in other vertebrates, with a clear distinction between the Saharo-Arabian-Sindian and Euro-Mediterranean herpetofaunas. Unlike other vertebrates, in reptiles the highest uniqueness and endemism is observed in dry climates, but the velocity of climate change during the Quaternary remains a major driver of endemism across all the vertebrates.

Traditionally, analyses of relationships between amphibians and habitat focused on breeding environments (i.e., pond features) more than on the features of the surrounding environment. Nevertheless, for most amphibians the terrestrial phase is longer than the aquatic phase, and consequently landscape features (i.e., habitat mosaics) may have an important role for modelling amphibian distribution. There were different aims in this analysis. Firstly, we compared the effectiveness of the information provided by land cover/use (LC/LU) classes and habitat classes defined according to a new habitat taxonomy named General Habitat Category (GHC), which is based on the concept of biological forms of dominant vegetation and class naturalness. The GHC map used was obtained from a pre-existing validated LC/LU map, by integrating spectral and spatial measurements from very high resolution Earth observation data according to ecological expert rules involving concepts related to spatial and temporal relationships among LC/LU and habitat classes. Then, we investigated the importance for amphibians of the landscape surrounding ponds within the Italian Alta Murgia National Park. The work assessed whether LC/LU classes in pond surrounds are important for the presence/absence of amphibians in this area, and identified which classes are more important for amphibians. The results obtained can provide useful indications to management strategies aiming at the conservation of amphibians within the study area. An information-theoretic approach was adopted to assess whether GHC maps allow to improve the performance of species distribution models. We used the Akaike's Information Criterion (AICc) to compare the effectiveness of GHC categories versus LC/LU categories in explaining the presence/absence of pool frogs. AICc weights suggest that GHC categories can better explain the distribution of frogs, compared to LC/LU classes.

Aim Habitat loss and degradation are the factors threatening the largest number of amphibian species. However, quantitative measures of habitat availability only exist for a small subset of them. We evaluated the relationships between habitat availability, extinction risk and drivers of threat for the world's amphibians. We developed deductive habitat suitability models to estimate the extent of suitable habitat and the proportion of suitable habitat (PSH) inside the geographic range of each species, covering species and areas for which little or no high-resolution distribution data are available. Location Global. Methods We used information on habitat preferences to develop habitat suitability models at 300-m resolution, by integrating range maps with land cover and elevation. Model performance was assessed by comparing model output with point localities where species were recorded. We then used habitat availability as a surrogate of area of occupancy. Using the IUCN criteria, we identified species having narrow area of occupancy, for which extinction risk is likely underestimated. Results We developed models for 5363 amphibians. Validation success of models was high (94%), being better for forest specialists and generalists than for open habitat specialists. Generalists had proportionally more habitat than forest or open habitat specialists. The PSH was lower for species having small geographical ranges, currently listed as threatened, and for which habitat loss is recognized as a threat. Differences in habitat availability among biogeographical realms were strong. We identified 61 forest species for which the extinction risk may be higher that currently assessed in the Red List, due to limited extent of suitable habitat. Main conclusions Habitat models can accurately predict amphibian distribution at fine scale and allow describing biogeographical patterns of habitat availability. The strong relationship between amount of suitable habitat and extinction threat may help the conservation assessment in species for which limited information is currently available.

Body size is influenced by the interaction of multiple forces, whose effects can determine the occurrence of sexual size dimorphism (SSD). Rensch's rule is the increase of SSD with body size in taxa where males are the largest sex, and the opposite pattern in female-biased SSD taxa. This pattern was detected in many animal groups, but contrasting results were also highlighted. This study evaluated the existence of Rensch's patterns for body size and for the number of caudal vertebrae in salamandrid caudate amphibians. Furthermore, we tested the support of alternative hypotheses on processes that may determine allometric patterns: sexual selection, fecundity selection and constraining selection by performing separate analyses on species with male- and female-biased SSD. We used the literature and original data to gather information on body size and number of caudal vertebrae in 52 species of salamandrids over four continents. We then tested the support of the three hypotheses using a phylogenetic approach. Rensch's rule was valid for body size in salamanders only for species with male-biased dimorphism. No allometric relationships were detected by analyses on all the species, or by analyses on female-biased SSD species. Analyses performed on the number of caudal vertebrae showed no significant patterns. Our study supports the role of sexual selection in promoting positive allometry for body size in male-biased SSD species, whereas the alternative hypotheses were not supported by our data. These results highlight the importance of distinguishing male- and female-biased species as different evolutionary pressures and constraints may be at the basis of evolution of SSD in these groups. © 2014 The Zoological Society of London.

Risk assessment allows the identification of non-native species most likely to become invasive and cause harm, and helps to set up preventive measures such as trade regulations. Freshwater turtles are among the most traded pets; an increasing number of species are easily available and frequently released by owners in natural wetlands. This study identified a pool of freshwater turtles frequently traded at cheap prices, and performed risk assessment at multiple steps of the invasion process. Establishment risk was assessed through species distribution models (MaxEnt and Boosted Regression Trees) based on global presence records and bioclimatic variables. We also analyzed ecological and life history traits favouring release, establishment and population growth. Besides the already invasive Trachemys scripta, at least 14 species are easily found in the pet market. For most of them, species distribution models identified areas with suitable climate outside the native range. Validation with independent data confirmed the reliability of the modelling approach. Pelodiscus sinensis and Pelomedusa subrufa had the broadest areas of suitable climate outside the native range. For all the species, possibility of coexistence with humans and reproductive traits suggest high risk of invasion, if introduced in areas with suitable climate. The availability of spatially explicit maps of risk allows to identify areas where preventive measures are urgently needed. In Europe, an expansion of trade regulations is needed to avoid that multiple freshwater turtles become invasive.

Invasive alien species can have complex effects on native ecosystems, and interact with multiple components of food webs, making it difficult a comprehensive quantification of their direct and indirect effects. We evaluated the relationships between the invasive crayfish, Procambarus clarkii, amphibian larvae and predatory insects, to quantify crayfish impacts on multiple levels of food webs, and to evaluate whether crayfish predation of aquatic insects has indirect consequences for their preys. We used pipe sampling to assess the abundance of crayfish, amphibian larvae and their major predators (Ditiscidae, Notonectidae and larvae of Anisoptera) in invaded and uninvaded ponds within a human dominated landscape. We disentangled the multivariate effects of P. clarkii on different components of food web through a series of constrained redundancy analyses. The crayfish had a negative, direct impact on both amphibian communities and their predators. Amphibian abundance was negatively related to both predators. However, the negative, direct effects of crayfish on amphibians were much stronger than predation by native insects. Our results suggest that this crayfish impacts multiple levels of food webs, disrupting natural prey-predator relationships.

Measuring a species decline is pivotal to evaluate their conservation status, but an accurate assessment of demographic trends requires observations collected across broad spatial and temporal scales. Volunteers can help to collect information over large scales, but their data may be affected by heterogeneity for sampling efforts and protocols, which may influence detection probability. Ignoring this issue may conduct to misleading conclusions. Here we show that data collected by different volunteer groups can be integrated with measures of sampling efforts, to obtain information on large scale demographic trends. We collected data on 33 common toad (Bufo bufo) populations across Italy for the period 1993-2010. We used two approaches (meta-analysis; analysis of average change in population size) to evaluate the overall demographic trend. We incorporated measures of volunteer sampling efforts into analyses, to take into account changes in detection probability. Toad abundance significantly declined in the last decade. From 2000 to 2010, 70% of populations showed a strong decline, and only 10% increased. Trends were heterogeneous among populations, but taking into account sampling effort reduced heterogeneity by 40%. We detected a 76% cumulative average decline of toad populations, despite an increasing mean sampling effort. The widespread toad decline rises concern for its future, also because the causes remain unclear. Volunteer data can be extremely useful to identify large scale population trends, if information on sampling effort are recorded and used to adjust counts. © 2011 Elsevier Ltd.

Egg provisioning is a major maternal effect in amphibians. We evaluated the relationship between starting body size (a proxy of egg provisioning) and multiple measures of larval performance in the Italian agile frog Rana latastei; we analysed within-clutch variation, to remove co-variation between provisioning and genetic maternal effect. We reared tadpoles from multiple clutches in a common environment under two food treatments (high- and low-protein content), and measured the mortality, tadpole size during development and development rate. We used a Bayesian framework (Markov chain Monte Carlo generalized linear mixed models) for the multivariate analysis of performance measures. Tadpoles with a large starting size remained the largest ones through the entire larval development, and attained metamorphosis earlier. Food with a high-protein content reduced mortality and increased the growth and development rate; the choice of food may be important in captive-breeding/headstarting programmes. We did not detect effects of the interaction between provisioning and type of food on tadpole performance. Our study confirms the importance of egg provisioning in amphibians, showing that it can affect multiple traits, and that their effects can last through the entire larval development. © 2010 The Authors. Journal of Zoology © 2010 The Zoological Society of London.

Fragmentation is a major cause of biodiversity loss. The relationship between fragmentation and biodiversity might be non-linear, due to the presence of ecological thresholds; however, the application of the threshold concept on the conservation of herb biodiversity has received limited attention. We assessed the relationship between a pool of woodland indicators and features of forest fragments (area, isolation, shape), and we evaluated whether ecological thresholds might provide guidelines for conservation. We performed our study in a human dominated area of northern Italy. In order to obtain a group of floristic indicators, we chose perennial herbs characteristic of the phytosociological syntaxa Fagetalia sylvaticae, Carpinion betuli and Erythronio-Carpinion, with suitable Landolt L and H index, obtained from previous releve´ s in reference and high-quality forests. Subsequently, we analyzed the relationship between richness of indicators and patch features recorded in a highly fragmented landscape. Generalized linear models showed that the number of forest indicators was positively related to fragment size and connectivity. Generalized Additive Models showed that the relationship between indicator richness and fragment size was non-linear, with the presence of two thresholds. The number of forest indicators increased until 35–40 ha; above this size the richness remained constant. Fragments above this threshold should be the target of conservation. Furthermore, the relationship between area and number of indicators was less steep in patches smaller than 1–1.5 ha. Patches between these two thresholds can be optimal targets of management actions, as small size increases can greatly improve their value for biodiversity. The identification of two thresholds in the relationship between patch area and indicators suggests an abrupt response to changing landscape features and provide quantitative targets for conservation.

Aim: The theory of island biogeography predicts species richness based on geographical factors that influence the extinction-colonization balance, such as area and isolation. However, human influence is the major cause of present biotic changes, and may therefore modify biogeographical patterns by increasing extinctions and colonizations. Our aim was to evaluate the effect of human activities on the species richness of reptiles on islands. Location: Islands in the Mediterranean Sea and Macaronesia. Methods: Using a large data set (n = 212 islands) compiled from the literature, we built spatial regression models to compare the effect of geographical (area, isolation, topography) and human (population, airports) factors on native and alien species. We also used piecewise regression to evaluate whether human activities cause deviation of the species-area relationship from the linear (on log-log axes) pattern, and path analysis to reveal the relationships among multiple potential predictors. Results: The richness of both native and alien species was best explained by models combining geographical and human factors. The richness of native species was negatively related to human influence, while that of alien species was positively related, with the overall balance being negative. In models that did not take into account human factors, the relationship between island area and species richness was not linear. Large islands hosted fewer native species than expected from a linear (on log-log axes) species-area relationship, because they were more strongly affected by human influence than were small islands. Path analysis showed that island size has a direct positive effect on reptile richness. However, area also had a positive relationship with human impact, which in turn mediated a negative effect on richness. Main conclusion: Anthropogenic factors can strongly modify the biogeographical pattern of islands, probably because they are major drivers of present-day extinctions and colonizations and can displace island biodiversity from the equilibrium points expected by theory on the basis of geographical features. © 2009 The Authors Journal compilation © 2009 Blackwell Publishing.

International audience; Aim Species richness is one of the commonest measures of biodiversity, and is a basis for analyses at multiple scales. Data quality may affect estimations of species richness, but most broad-scale studies do not take sampling biases into account. We analysed reptile richness on islands that have received different sampling efforts, and assessed how inventory completeness affects the results of ecogeographical analyses. We also used simulations to evaluate under what circumstances insufficient sampling can bias the outcome of biodiversity analyses. Location Mediterranean islands. Methods We gathered data on reptile richness from 974 islands, assuming better sampling in islands with specific inventories. We used Moran's eigenvector mapping to analyse the factors that determine whether an island has been surveyed, and to identify the relationships between reptile richness, geographical parameters and anthropic parameters. We simulated islands, mimicking patterns of true data, and sampled them with varying effort. Simulated richness was analysed using the same approach used for real-world data. Results The probability that islands were sampled for reptiles was higher in large, human-populated islands. The relationship between human impact and reptile richness was negative in well-surveyed islands, but positive in islands that had not been systematically surveyed, because densely populated and accessible islands receive better sampling. In simulations, analyses successfully retrieved the relationships between species richness and human presence only if the average species detection probability was ≥75%. Poorer sampling resulted in biased regression results. Main conclusions Human activities may strongly affect biodiversity, but human presence and accessibility improve sampling effort and thus the quality of biodiversity information. Therefore, regressing known species richness on parameters representing human presence may result in apparent positive relationships. These two facets of human presence (positive on biodiversity knowledge, negative on actual biodiversity) represent a major challenge for ecogeographical studies, as not taking them into account would bias analyses and underestimate human impact.

Aim Maps of species ranges are among the most frequently used distribution data in biodiversity studies. As with any biological data, range maps have some level of measurement error, but this error is rarely quantified. We assessed the error associated with amphibian range maps by comparing them with point locality data. Location Global. Methods The maps published by the Global Amphibian Assessment were assessed against two data sets of species point localities: the Global Biodiversity Information Facility (GBIF), and a refined data set including recently published, high-quality presence data from both GBIF and other sources. Range fit was measured as the proportion of presence records falling within the range polygon(s) for each species. Results Using the high-quality point data provided better fit measures than using the raw GBIF data. Range fit was highly variable among continents, being highest for North American and European species (a fit of 84–94%), and lowest for Asian and South American species (a fit of 57–64%). At the global scale, 95% of amphibian point records were inside the ranges published in maps, or within 31 km of the range edge. However, differences among continents were striking, and more points were found far from range edges for South American and Asian species. Main conclusions The Global Amphibian Assessment range maps represent the known distribution of most amphibians well; this study provides measures of accuracy that can be useful for future research using amphibian maps as baseline data. Nevertheless, there is a need for greater investment in the continuous updating and improvement of maps, particularly in the megadiverse areas of tropical Asia and South America.

At the local spatial scale, land-use variables are often employed as predictors for ecological niche models (ENMs). Remote sensing can provide additional synoptic information describing vegetation structure in detail. However, there is limited knowledge on which environmental variables and how many of them should be used to calibrate ENMs. We used an information-theoretic approach to compare the performance of ENMs using different sets of predictors: (1) a full set of land-cover variables (seven, obtained from the LGN6 Dutch National Land Use Database); (2) a reduced set of land-cover variables (three); (3) remotely sensed laser data optimized to measure vegetation structure and canopy height (LiDAR, light detection and ranging); and (4) combinations of land cover and LiDAR. ENMs were built for a set of bird species in the Veluwe Natura 2000 site (the Netherlands); for each species, 26–214 records were available from standardized monitoring. Models were built using MaxEnt, and the best performing models were identified using the Akaike’s information criterion corrected for small sample size (AICc). For 78% of the bird species analysed, LiDAR data were included in the best AICc model. The model including LiDAR only was the best performing one in most cases, followed by the model including a reduced set of land-use variables. Models including many land-use variables tended to have limited support. The number of variables included in the best model increased for species with more presence records. For all species with 33 records or less, the best model included LiDAR only. Models with many land-use variables were only selected for species with >150 records. Test area under the curve (AUC) scores ranged between 0.72 and 0.92. Remote sensing data can thus provide regional information useful for modelling at the local and landscape scale, particularly when presence records are limited. ENMs can be optimized through the selection of the number and identity of environmental predictors. Few variables can be sufficient if presence records are limited in number. Synoptic remote sensing data provide a good measure of vegetation structure and may allow a better representation of the available habitat, being extremely useful in this case. Conversely, a larger number of predictors, including land-use variables, can be useful if a large number of presence records are available.

Aim The incompleteness of information on biodiversity distribution is a major issue for ecology and conservation. Researchers have made many attempts to quantify the amount of biodiversity that still remains unknown. We evaluated whether models that integrate ecogeographical variables with measures of the effectiveness of sampling can be used to estimate biodiversity patterns (species richness) of reptiles in remote areas that have received limited surveys. Location The Western Palaearctic (Europe, Northern Africa, the Middle East and Central Asia). Methods We gathered data on the distribution of turtles, amphisbaenians and lizards. We used regression models integrating spatial autocorrelation (spatial eigenvector mapping and Bayesian autoregressive models) to analyse species richness, and identified relationships between species richness, ecogeographical features and large-scale measures of accessibility. Results The two regression techniques were in agreement. Known species richness was dependent on ecogeographical factors, peaking in areas with high temperature and annual actual evapotraspiration, and intermediate cover of natural vegetation. However, richness declined sharply in the least accessible areas. Our models revealed regions where reptile richness is likely to be higher than currently known, particularly in the biodiversity hotspots in the south of the Arabian Peninsula, the Irano-Anatolian region, and the Central Asian mountains. An independent validation data set, with distribution data collected recently throughout the study region, confirmed that combining accessibility measures with ecogeographical variables allows a good estimate of reptile richness, even in remote areas that have received limited monitoring so far. Some remote regions that support very rich communities are covered very little by protected areas. Main conclusions Integrating accessibility measures into species distribution models allows biologists to identify areas where current knowledge underestimates the actual richness of reptiles. Our study identifies regions requiring future biodiversity research, proposes a novel approach to biodiversity prediction in poorly studied areas, and identifies potential regions for conservation.

The evolution of sexual dimorphism is an important topic of evolutionary biology, but few studies have investigated the determinants of sexual dimorphism over broad phylogenetic scales. The number of vertebrae is a discrete character influencing multiple traits of individ- uals, and is particularly suitable to analyze processes determining morphological variation. We evaluated the support of multiple hypotheses concerning evolutionary processes that may cause sexual dimorphism in the number of caudal vertebrae in Urodela (tailed amphibians). We obtained counts of caudal vertebrae from (2,000 individ- uals representing 27 species of salamanders and newts from Europe and the Near East, and integrated these data with a molecular phylogeny and multiple information on species natural history. Per each species, we estimated sexual dimorphism in caudal vertebrae number. We then used phylogenetic least squares to relate this sexual dimorphism to natural history features (courtship complexity, body size dimorphism, sexual ornamentation, aquatic phenology) representing alternative hypotheses on processes that may explain sexual dimorphism. In 18 % of species, males had significantly more caudal vertebrae than females, while in no species did females have significantly more caudal vertebrae. Dimorphism was highest in species where males have more complex courtship behaviours, while the sup- port of other candidate mechanisms was weak. In many species, males use the tail during courtship displays, and sexual selection probably favours tails with more vertebrae. Dimorphism for the number of tail vertebrae was unrelated to other forms of dimorphism, such as sexual ornamenta- tion or body size differences. Multiple sexually dimorphic features may evolve independently because of the interplay between sexual selection, fecundity and natural selection.

Trachemys scripta, the slider terrapin, has been traded worldwide since at least the 1950s, and quickly became a very popular pet because of its cheap price and the reasonably simple husbandry. Sliders are probably the most commonly traded reptile: More than 52 million individuals were exported from the US during the period 1989–1997 (Telecky, 2001). Although sliders are mostly traded as pets, in some areas they are also imported or farmed for human consumption, particularly in Asia (Scalera, 2007). Three subspecies of T. Scripta are currently recognized (Bonin et al, 2006): Trachemys scripta scripta (Thunberg in Schoepff, 1792), T. S. Elegans (Wied, 1838) and T. S. Troostii (Holbrook, 1836) (Figure 28.1). Trachemys scripta elegans (the redeared slider terrapin) was the most widely traded subspecies until 1997. The European Union interrupted the import of T. S. Elegans in 1997 (Regulation 338/1997; Regulation 349/2003) due to the high risk of biological invasion. However, these regulations considered only the subspecies T. S. Elegans and, as a consequence, the trade in the other two subspecies (T. S. Scripta, T. S. Troostii and hybrids among subspecies) sharply increased after the ban (Scalera, 2007). Young sliders are sold at a size of just a few centimetres, but can grow quickly. As owners are rarely prepared to maintain large adults for many years, they often release terrapins into natural or semi-natural wetlands (Teillac- Deschamps et al, 2009).

Spatial autocorrelation (SAC) is often observed in species distribution data, and can be caused by exogenous, autocorrelated factors determining species distribution, or by endogenous population processes determining clustering such as dispersal. However, it remains debated whether SAC patterns can actually reveal endogenous processes. We reviewed studies measuring dispersal of the salamander Salamandra salamandra , to formulate a priori hypotheses on the scale at which dispersal is expected to determine population distribution. We then tested the hypotheses by analysing SAC in distribution data, and evaluating whether controlling for the eff ect of environmental variables can reveal endogenous processes. We surveyed 565 streams to obtain species distribution data; we also recorded landscape and microhabitat features known to aff ect the species. We used multiple approaches to tease apart endogenous and exogenous SAC: the analysis of residuals of logistic regression models considering diff erent environmental variables; the analysis of eigenvectors extracted by several implementations of spatial eigenvector mapping. In capture – mark – recapture studies, 98% of individuals moved 500 m or less. Both species distribution and environmental features were strongly autocorrelated. Th e residuals of logistic regression relating species to environmental variables were autocorrelated at distances up to 500 m; analyses considering diff erent sets of environmental variables, or assuming non-linear species habitat relationships, yielded identical results. Th e results of spatial eigenvector mapping strongly depended on the matrix of distances used. Nevertheless, the eigenvectors of models with best fi t were autocorrelated at distances up to 200 – 500 m. Th e concordance between multiple approaches suggests that 500 m is the scale at which dispersal connects breeding localities, increasing probability of occurrence. If exogenous variables are correctly identifi ed, the analysis of SAC can provide important insights on endogenous population processes, such as the fl ow of individuals. SAC analysis can also provide important information for conservation, as the existence of metapopulations or population networks is essential for long term persistence of amphibians.

Complex spatial dynamics are frequent in invasive species; analyzing distribution patterns can help to understand the mechanisms driving invasions. We used different spatial regression techniques to evaluate processes determining the invasion of the red swamp crayfish Procambarus clarkii. We evaluated four a priori hypotheses on processes that may determine crayfish invasion: landscape alteration, connectivity, wetland suitability for abiotic and biotic features. We assessed the distribution of P. clarkii in 119 waterbodies in a recently invaded area. We used spatially explicit statistical techniques (spatial eigenvector mapping, generalized additive models, Bayesian intrinsic conditional autoregressive models) within an information-theoretic framework to assess the support of hypotheses; we also analyzed the pattern of spatial autocorrelation of data, model residuals, and eigenvectors. We found strong agreement between the results of spatial eigenvector mapping and Bayesian autoregressive models. Procambarus clarkii was significantly associated with the largest, permanent wetlands. Additive models suggested also association with human-dominated landscapes, but tended to overfit data. The results indicate that abiotic wetlands features and landscape alteration are major drivers of the species’ distribution. Species distribution data, residuals of ordinary least squares regression, and spatial eigenvectors all showed positive and significant spatial autocorrelation at distances up to 2,500 m; this may be caused by the dispersal ability of the species. Our analyses help to understand the processes determining the invasion and to identify the areas most at risk where screening and early management efforts can be focused. The comparison of multiple spatial techniques allows a robust assessment of factors determining complex distribution patterns.

Semiaquatic organisms depend on the features of both water bodies and landscapes; the interplay between terrestrial and aquatic systems might influence the semiaquatic communities, determining the scale at which management would be more effective. However, the consequences of such interplay are not frequently quantified, particularly at the community level. We analyzed the distribution of amphibians to evaluate whether the influence of landscape features on freshwater ecosystems can have indirect consequences at both the species and community level. We surveyed 74 streams in northern Italy to obtain data on breeding amphibians, water, and microhabitat features; we also measured features of surrounding landscapes. We used an information-theoretic approach and structural equation models to compare hypotheses on causal relationships between species distribution and variables measured at multiple levels. We also used a constrained redundancy analyses to evaluate causal relationships between multivariate descriptors of habitat features and community composition. Distribution of Salamandra salamandra was related to landscape, hydrological, and water characteristics: salamanders were more frequent in permanent streams with low phosphate concentration within natural landscapes. Water characteristics were dependent on landscape: streams in natural landscapes had less phosphates. Landscape influenced the salamander both directly and indirectly through its influence on phosphates. Community structure was determined by both landscape and water characteristics. Several species were associated with natural landscapes, and with particular water characteristics. Landscape explained a significant proportion of variability of water characteristics; therefore it probably had indirect effects on community. Upland environments play key roles for amphibians, for example, as the habitat of adults, but upland environments also have indirect effects on the aquatic life stages, mediated through their influence on water characteristics. Synergistic effects can magnify the negative consequences of landscape alteration on amphibians; landscape management can be particularly effective, as it can also improve wetland features. © 2011 by the Ecological Society of America.

Aim Early assessment of the impact of invasive alien species is crucial to set up timely management, but often the impact is evident when it is too late for action. We evaluated relationships between the alien crayfish, Procambarus clarkii, the distribution of native amphibians, and the abundance of their larvae. We assessed whether considering measures of reproductive success provide a more prompt measure of impact than considering just species distribution. Location One hundred and twenty-five wetlands in Northern Italy, in an area recently invaded by P. clarkii. Methods We surveyed wetlands to assess the presence of breeding activity of amphibians and the distribution of P. clarkii. We measured the abundance of amphibian larvae before metamorphosis through pipe sampling. We built models analysing the relationships between amphibian and crayfish distribution, while taking into account spatial autocorrelation and environmental features. Analyses were performed at both the species level (generalized linear models and spatial eigenvector mapping) and community level (constrained redundancy analysis). Results In terms of breeding site distribution, only two amphibians (Lissotriton vulgaris and Hyla intermedia) were negatively associated with P. clarkii, while the relationships between other the species and P. clarkii were positive or not significant. However, larval abundance for all amphibian species was negatively associated with the alien crayfish. Analyses performed at community and single species levels yielded consistent results. Main conclusions Procambarus clarkii impacts amphibians through different processes. Newts probably avoid invaded wetlands for breeding. Other species attempt breeding in wetlands with crayfish, but suffer very low success. Considering distribution data alone would not provide a correct picture of the impact of this alien species; measures of reproductive success may allow a more accurate assessment of the impact.

Aim Ecogeographical variation of body size in vertebrates (e.g. Bergmann's rule) has long been recognized. However, the patterns and causes of intra-specific ecogeographical variation of body size in ectotherms, and in amphibians in particular, are strongly debated. We identified the relationship between bioclimatic variables and body size predicted a priori by alternative hypotheses (heat balance, endurance, seasonality, starvation resistance, water availability, primary productivity, parental investment) proposed to explain ecogeographical patterns of body size in ectotherms, and we evaluated the relative support of these hypotheses in explaining variation in body size of the Italian crested newt, Triturus carnifex. Location Twenty-three populations covering the whole range of T. carnifex (Austria, Croatia, Italy and Slovenia). Methods We obtained data on body size (snout-vent length, SVL) of 2639 adult newts from direct measurements and the literature; we obtained high-resolution environmental data for the sampled localities. We used an information-theoretic approach to evaluate the support of the data for the different hypotheses. We also integrated information on population genetics in our models. Results We observed strong geographical variation of body size. The best Akaike information criterion (AIC) models showed that populations with larger body size are associated with cold climates and secondarily with high primary productivity. Furthermore, sexual dimorphism increases in cold climates, as the increase in body size was stronger for females. When taking into account population genetics, we did not find support for relationships with the other variables. Main conclusion Our results are consistent with three hypotheses proposed to explain ecogeographical variation in amphibians: heat balance, increased parental investment of females and productivity. Information theory provides the framework for comparing hypotheses rather than looking for patterns. We suggest that evaluating the support for mechanisms can provide better insights than simply assessing whether ecogeographical variation is in agreement with some 'rule'. Universita degli Studi di Milano Bicocca; FRS-FNRS [1.5.010.09]; Serbian Ministry of Science and Technological Development [143052]

Biological invasions and land-use changes are two major causes of the global modifications of biodiversity. Habitat suitability models are the tools of choice to predict potential distributions of invasive species. Although land-use is a key driver of alien species invasions, it is often assumed that land-use is constant in time. Here we combine historical and present day information, to evaluate whether land-use changes could explain the dynamic of invasion of the American bullfrog Rana catesbeiana ( 5Lithobathes catesbeianus) in Northern Italy, from the 1950s to present-day. We used MAXENT to build habitat suitability models, on the basis of past (1960s, 1980s) and present-day data on land-uses and species distribution. For example, we used models built using the 1960s data to predict distribution in the 1980s, and so on. Furthermore, we used land-use scenarios to project suitability in the future. Habitat suitability models predicted well the spread of bullfrogs in the subsequent temporal step. Models considering land-use changes predicted invasion dynamics better than models assuming constant land-use over the last 50 years. Scenarios of future land-use suggest that suitability will remain similar in the next years. Habitat suitability models can help to understand and predict the dynamics of invasions; however, land-use is not constant in time: land-use modifications can strongly affect invasions; furthermore, both land management and the suitability of a given land-use class may vary in time. An integration of land-use changes in studies of biological invasions can help to improve management strategies.

Effective population size (Ne) is a key determinant of genetic diversity of populations. In amphibians, the ratio effective population size/census size (Ne/N) is often very low, raising concerns for the long-term persistence of genetic diversity in isolated populations. It has been proposed that the phenomenon of 'genetic compensation' increases the ratio Ne/N in small populations, but the underlying mechanisms are poorly understood. Polygyny can decrease Ne/N because of the negative relationship between polygyny and Ne. We used genetic information (microsatellites) to evaluate the relationship between census size, polygyny and Ne in populations of the threatened Italian agile frog Rana latastei. We reconstructed parentage in tadpoles from nine populations with eight to 32 breeding females, using a likelihood-based method; we analysed simulated datasets with known properties to confirm the reliability of this approach in reconstructing polygyny. Furthermore, we estimated Ne using approximate Bayesian computation. The level of polygyny differed strongly among populations (average number of mates per breeding male: 2-6.4). Polygyny was greater in populations with larger census sizes. Moreover, variance in male mating success was larger in large populations. Effective population size increased with population size, but was negatively related to polygyny; as polygyny increased in large populations, this was associated with reduced Ne/N. In polygynous species, increasing levels of polygyny in large populations may explain the low Ne/N values, with important implications for the conservation of genetic diversity and for long-term population persistence. © 2009 The Authors. Journal compilation © 2009 The Zoological Society of London.

The Northern Areas of Pakistan are at the boundary between the Paleartic and the Oriental biogeographical realm. This mountainous region is at the junction between major mountain ranges, has huge altitudinal and environmental gradients, and is the focus of efforts for biodiversity conservation. However, the amphibians and reptiles of this area remain poorly known. We used multiple approaches to describe species distribution and ecology, to perform a preliminary analysis of genetic diversity of toads, and to assess the occurrence of Batrachochytrium dendrobatidis, a pathogen largely responsible of global amphibian decline. We observed seven species of amphibians and reptiles: Bufo pseudoraddei baturae, Bufo latastii, Scutiger cf. nyingchiensis, Altiphylax stoliczkai, Laudakia himalayana, L. pakistanica and Varanus bengalensis; we describe the habitat and distribution of these species. In the case of L. himalayana, we observed a bimodal pattern of diurnal activity, and we report new data on the altitudinal range of this agamid. Sequences of a fragment of mitochondrial 16S rDNA from multiple populations of B. pseudraddei baturae show low genetic diversity among individual of this species. Conversely, we observed strong genetic substructuring among populations of B. latastii living in different valleys. A PCR-based analysis did not reveal the presence of B. dendrobatidis in any of the amphibians investigated. Distribution data show that amphibians and reptiles are limited to relatively low elevations; these areas suffer the strongest human impact, and might be overlooked by future conservation plans for the area, making the future of these organisms at risk. © NwjZ, Oradea, Romania, 2010.

Aim General patterns of biodiversity, such as latitudinal gradients and species-area relationships, are found consistently in a wide range of organisms, but recent results for protist diversity suggest that organisms shorter than 2 mm do not display such patterns. We tested this prediction in bdelloid rotifers, pluricellular metazoans smaller than 2 mm, but with size and ecology comparable to protists. Location A single valley in northern Italy was surveyed in detail and compared to all available faunistic data on bdelloids worldwide. Methods We analysed 171 local assemblages of bdelloid rotifers living in 5 systems of dry mosses and submerged mosses in running water and in lakes. We compared patterns of alpha, beta, and gamma diversity, and nestedness of metacommunities, with those known from protists and larger organisms. Results Bdelloid rotifers showed low local species richness (alpha diversity), with strong habitat selection, as observed in larger organisms. The number of species differed among systems, with a higher number of species in dry than in aquatic mosses. There was no hierarchical structure or exclusion of species in the metacommunity pattern within each system. Local diversity for the entire valley was surprisingly high compared with worldwide bdelloid diversity, similar to observed patterns in protists. Main Conclusions Bdelloid rotifers have some of the peculiarities of protist biodiversity, although at slightly different spatial scales, thus confirming the idea of a major change in biodiversity patterns among organisms shorter than 2 mm. However, bdelloids show stronger habitat selection than protists. We suggest two possible explanations for the observed patterns: (1) dispersal is very rare, and not all bdelloid clones are arriving everywhere; and (2) dispersal is effective in displacing propagules, but environmental heterogeneity is very high and prevents many species from colonizing a given patch of moss.

Non-native invasive species establish in favourable habitats in alien regions. Such favourable habitats are largely determined by local climatic, soil and biogeographic factors. Modelling these factors can help managers to identify areas of possible risk of invasion. This paper uses logistic regression modelling to identify variables conducive to high invasion in a tropical mixed forest in a biodiversity hotspot region in India. Using presence-absence data of an invasive species Lantana camara and local habitat variables from increasing buffer distances around sampling locations along with broad scale climatic parameters, we identify the variables that support invasion and spread. Results indicated that the percentage of moist deciduous forest at a distance of 50 m around the plot was significantly related to the invasion of L. camara. The study demonstrates the facilitation by moist deciduous forests to the growth and spread of L. camara in this region, and highlights the importance of using data at multiple scales for modelling invasion.

Crop damages by wildlife is a frequent form of human-wildlife conflict. Identifying areas where the risk of crop damages is highest is pivotal to set up preventive measures and reduce conflict. Species distribution models are routinely used to predict species distribution in response of environmental changes. The aim of this paper was assessing whether species distribution models can allow to identify the areas most at risk of crop damages, helping to set up management strategies aimed at the mitigation of human-wildlife conflicts. We obtained data on wild boar Sus scrofa damages to crops in the Alta Murgia National Park, Southern Italy, and related them to landscape features, to identify areas where the risk of wild boar damages is highest. We used MaxEnt to build species distribution models. We identified the spatial scale at which landscape mostly affects the distribution damages, and optimized the regularization parameter of models, through an information-theoretic approach based on AIC. Wild boar damages quickly increased in the period 2007-2011; cereals and legumes were the crops more affected. Large areas of the park have a high risk of wild boar damages. The risk of damages was related to low cover of urban areas or olive grows, intermediate values of forest cover, and high values of shrubland cover within a 2-km radius. Temporally independent validation data demonstrated that models can successfully predict damages in the future. Species distribution models can accurately identify the areas most at risk of wildlife damages, as models calibrated on data collected during only a subset of years correctly predicted damages in the subsequent year.

Fragmentation has negative effects on ecosystems and can cause loss of habitats, increase of edges and isolation. Forests in northern Italy have strongly declined, because of the development of urban land, infrastructures and crops. In suburban areas forest patches often perform a variety of functions. This study used scenarios integrating both ecological and social principles to improve landscape multifunctionality in a suburban area of Northern Italy, with a special focus on the role of woody patches. We evaluated how improving some functions of woody patches (suitability for forest species, mitigation for road impact and recreation) can help creating a multifunctional landscape. We combined the scenario visualisation through GIS, the maximization of functions based on ecological principles, and the use of fuzzy logic. The scenarios obtained show that improving existing woods can help to maximize multiple functions. The scenario improving recreation is the most suitable to increase biodiversity, and it can also help to mitigate road impact. The scenario approach can help decision-makers during the planning process, because it is user-friendly. Comparing multiple scenarios can allow assessing if managing the landscape for one function may also accomplish other function(s).