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Experimental introductions of species have provided some of the most tractable examples of rapid phenotypic changes, which may reflect plasticity, the impact of stochastic processes, or the action of natural selection. Yet to date, very few studies have investigated the neutral and potentially adaptive genetic impacts of experimental introductions. We dissect the role of these processes in shaping the population differentiation of wall lizards in three Croatian islands (Sušac, Pod Kopište, and Pod Mrčaru), including the islet of Pod Mrčaru, where experimentally introduced lizards underwent rapid (~30 generations) phenotypic changes associated with a shift from an insectivorous to a plant‐based diet. Using a genomic approach (~82,000 ddRAD loci), we confirmed a founder effect during introduction and very low neutral genetic differentiation between the introduced population and its source. However, genetic depletion did not prevent rapid population growth, as the introduced lizards exhibited population genetic signals of expansion and are known to have reached a high density. Our genome‐scan analysis identified just a handful of loci showing large allelic shifts between ecologically divergent populations. This low overall signal of selection suggests that the extreme phenotypic differences observed among populations are determined by a small number of large‐effect loci and/or that phenotypic plasticity plays a major role in phenotypic changes. Nonetheless, functional annotation of the outlier loci revealed some candidate genes relevant to diet‐induced adaptation, in agreement with the hypothesis of directional selection. Our study provides important insights on the evolutionary potential of bottlenecked populations in response to new selective pressures on short ecological timescales. Our study provides unprecedented information on how demographic expansion can help genetically impoverished populations successfully adapt to new environments. Such interplay between demography and selection can have a major role in the evolution of species responding to global changes, such as introduced species and species impacted by climate change.

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.

Aim The Mediterranean basin has a long history of interactions between humans and biota, with multiple ancient and recent introductions of alien species. Such a multitude of introductions makes it difficult to distinguish between alien and native species but provides an excellent opportunity to investigate factors related to introductions and long‐term persistence of alien species. In this study, we combined genetic and distribution data to identify the factors promoting the presence of alien reptiles on islands, considering human‐related, geographic and species features. Furthermore, we assessed whether the use of genetic evidence to identify alien species improves inference of the factors determining their distribution. Location Mediterranean islands. Methods We combined genetic data and distribution databases to obtain information on biological traits and on the native/alien status of reptiles on >900 Mediterranean islands, and we gathered data on geographic and human features of islands. We then used spatially explicit generalized additive mixed models to identify the factors associated with the establishment of alien reptiles. Results Alien reptile populations are more frequent on islands far from the native range and with large human population. Alien populations of reptiles that are able to feed on plants are particularly frequent. Traditional data sources underestimate the frequency of alien reptiles on Mediterranean islands, and using genetic evidence to assess the status of populations provided a more complete picture of the factors associated with the presence of alien populations. Main conclusions Humans are key drivers of the distribution of alien reptiles on Mediterranean islands, but the distributions are determined by a complex interplay between human activities, geographic factors and species features. Genetic data are essential for obtaining reliable biogeographic assessments of invasive species, particularly in systems with a long history of human influence.

The Aeolian wall lizard Podarcis raffonei is an island endemic that survives only on three tiny islets, and on the Capo Grosso peninsula of the Vulcano island, thus is among the European vertebrates with the smallest range and one of the most threatened by extinction. This species is declining due to competition and hybridization with the non-native lizard Podarcis siculus , but a regular monitoring program is lacking. Here we assessed the size and status of the Capo Grosso population of P . raffonei on Vulcano. In September 2015 we captured 30 individuals showing the typical brown phenotype of P . raffonei , while one single male showed a green phenotype, apparently intermediate between P . raffonei and the non-native Podarcis siculus . In May 2017, only 47% of 131 individuals showed the typical brown phenotype ( P . raffonei -like) and 53% showed the green phenotype ( P . siculus -like). Based on N -mixture models and removal sampling the estimated size of the Capo Grosso population was of 800–1300 individuals in 2017, being similar to 2015; available data suggest that the total range of the species could be as small as 2 ha. The frequency of individuals with the typical P . raffonei phenotype dramatically dropped between two samplings with a parallel increase of individuals displaying the green phenotype. Observation on outdoor captive-bred individuals demonstrates plasticity for colouration in P . raffonei individuals from Capo Grosso, with several individuals showing the typical brown pattern in September 2017 and a green pattern in March 2021. Non-exclusive hypotheses, including hybridization with P . siculus and plasticity in colour pattern of P . raffonei , are discussed to explain the phenotypic shifts of the P . raffonei population of Capo Grosso. While genomic evidence is required to reach conclusions and investigate eventual hybridization, it is urgent to undertake a programme for the monitoring and management of this lizard.

Biological invasions are a major conservation threat for biodiversity worldwide. Islands are particularly vulnerable to invasive species, especially Mediterranean islands which have suffered human pressure since ancient times. In the Balearic archipelago, reptiles represent an outstanding case with more alien than native species. Moreover, in the last decade a new wave of alien snakes landed in the main islands of the archipelago, some of which were originally snake-free. The identification of the origin and colonization pathways of alien species, as well as the prediction of their expansion, is crucial to develop effective conservation strategies. In this study, we used molecular markers to assess the allochthonous status and the putative origin of the four introduced snake species (Hemorrhois hippocrepis, Malpolon monspessulanus, Macroprotodon mauritanicus and Rhinechis scalaris) as well as ecological niche models to infer their patterns of invasion and expansion based on current and future habitat suitability. For most species, DNA sequence data suggested the Iberian Peninsula as the potential origin of the allochthonous populations, although the shallow phylogeographic structure of these species prevented the identification of a restricted source-area. For all of them, the ecological niche models showed a current low habitat suitability in the Balearic, which is however predicted to increase significantly in the next few decades under climate change scenarios. Evidence from direct observations and spatial distribution of the first-occurrence records of alien snakes (but also lizards and worm lizards) suggest the nursery trade, and in particular olive tree importation from Iberian Peninsula, as the main pathway of introduction of alien reptiles in the Balearic islands. This trend has been reported also for recent invasions in NE Spain, thus showing that olive trees transplantation may be an effective vector for bioinvasion across the Mediterranean. The combination of molecular and ecological tools used in this study reveals a promising approach for the understanding of the complex invasion process, hence guiding conservation management actions.

In recent decades, many reptile species have been introduced outside their native ranges, either accidentally through the transportation of goods and materials (e.g., plants, construction materials), but also intentionally through the pet trade. As a paradigmatic example, the Italian wall lizard, Podarcis siculus, native to the Italian Peninsula, Sicily and the north Adriatic coast, has been introduced in several nearby islands since historical times (Corsica, Sardinia, Menorca). Besides these regions, scattered populations were later reported from the Iberian Peninsula, France, Switzerland, Turkey, Greece, the United Kingdom and North America. Here, we provide molecular evidence regarding the introduction and origin of P. siculus in six new populations outside its native range: Romania (Bucharest and Alba Iulia), inland Croatia (Zagreb and Karlovac), Italy (Lampedusa Island) and Azerbaijan (Baku). Phylogenetic analysis suggests that the Alba Iulia (Romania) population originated from a single clade (Tuscany), while the population from Azerbaijan is admixed including two distinct clades, one similar to those found in Sicily and the other present across the Tuscany clade. Samples from Bucharest also have admixed origins in Tuscany and the Adriatic clades. Less surprisingly, samples from Zagreb and Karlovac are included in the Adriatic clade while those from Lampedusa originated from Sicily. Overall, our results further demonstrate that P. siculus is able to establish outside of its native range even under different climatic conditions, not particularly from specific clades or source areas. Also, for the first time in this species, our results indicate that repeated human introductions promote lineage admixture and enhance their invasive potential.

Biological invasions are a challenge to conservation and constitute a threat to biodiversity worldwide. The Italian wall lizard Podarcis sicula has been widely introduced, and seems capable of adapting to most of the regions where it is established and to impact on native biota. Here we construct a phylogenetic framework to assess the origin of the introduced populations in the United Kingdom, Greece and Turkey comparing cytochrome-b gene sequences of lizards from five locations to published sequences from the native range and other non-native locations. The results support an origin from central Italy for the United Kingdom population, from the Adriatic region for the Greek population and from Calabria for the population from Turkey. These results emphasise the multiple-source pattern of introduction of this species identified in previous studies. The improvement in the knowledge of the origin and pathways by which invaders arrive in new areas, as well as the monitoring of their populations, are crucial for successful strategies to deal with exotic species.

The continuous growth and movement of the human population is increasing the frequency of translocating species from their native ranges to novel environments. However, biological invasions offer a rare opportunity to investigate how species can colonise and adapt to new conditions. In that sense, Ecological Niche Models (ENMs) can be a powerful tool to predict where invasive species will spread over the next decades, although they depend heavily on climatic niche conservatism between native and exotic ranges. To reduce these uncertainties, ENMs can be refined by accounting for dispersal constraints. The common wall gecko, Tarentola mauritanica is a native and widespread Mediterranean lizard that has been introduced across different tropical and sub-tropical regions. In this study, we aim to predict the potential and future distribution of T. mauritanica geckos using correlative models, its potential colonization regions under a dispersal model, and the niche overlap between native and introduced populations. The correlative models predict that the most suitable geographic areas for this gecko correspond to Mediterranean-type ecosystems, such as California, central Chile, the Cape Region of South Africa, around the Caspian Sea, south-eastern Asia, and south-western and southern Australia. The species distribution models projected to 2061–2080, forecast that the range of T. mauritanica is likely to shift towards northern latitudes but, surprisingly, not to expand. According to the dispersal models, T. mauritanica will be able to colonise a similar geographic range compared to the one obtained with the correlative models for the future. Finally, the niche overlap results demonstrate that T. mauritanica ’s realised niche has not been conserved over space, as the naturalised climatic niche of the introduced populations differs significantly from its native one. The latter results suggest that there has been no climatic niche conservatism during the several introductions of T. mauritanica and that this species seems to be able to cope with novel and more humid environments, typical from the tropics.

CITATION: Ficetola, G. F. et al. 2021. Status of the largest extant population of the critically endangered Aeolian lizard Podarcis raffonei (Capo Grosso, Vulcano island). PLoS ONE, 16(6):e0253631, doi:10.1371/journal.pone.0253631.

Emerging in the 1990s, bioblitzes have become flagship events for biodiversity assessments. Although the format varies, a bioblitz is generally an intensive, short-term survey in a specific area. Bioblitzes collect biodiversity data and can therefore play a role in research, discovery of new species at a site and monitoring. They may also promote public engagement, community building, and education and outreach. However, the question remains, how effective are bioblitzes at achieving these goals? To evaluate the value of bioblitzes for these multiple goals, we conducted two meta-analyses, one on sixty published bioblitzes and the other on 1860 bioblitzes conducted using iNaturalist. Furthermore, we made an in-depth analysis of the data collected during a bioblitz we organized ourselves. From these analyses we found bioblitzes are effective at gathering data—collecting on average more than 300 species records—despite limitations of bias, which many types of biodiversity surveys suffer from, such as preferences for charismatic taxa, and uneven sampling effort in time and space. However, because the survey intensity, duration and extent are more controlled, a bioblitz is more repeatable than some other forms of survey. We also found that bioblitzes were highly effective at engaging people in sustained activity after they participated in a bioblitz. A bioblitz may therefore act as a trigger for participation in biological recording, which is supported by the use of technology, particularly smartphone apps. Another important aspect is the involvement of both citizen scientists and professional biologists, creating learning opportunities in both directions. Indeed, it was clear that many bioblitzes acted as brokerage events between individuals and organizations, and between professionals who work in biodiversity research and conservation. Such community building is important for communication and building trust between organizations and citizens to the benefit of biodiversity research and conservation. From the impartial perspective of hypothesis-driven science, bioblitzes may seem like a lot of work with limited scientific gain. However, this largely overlooks how important people, communities and their organizations are in gathering data, and in conserving biodiversity.