ABSTRACT
The Sardinian grass snake, Natrix helvetica cetti, is an endangered endemic snake subspecies with a restricted and highly fragmented geographic distribution. Information on its ecology and detailed geographic distribution are scarce and may negatively impact on its conservation status. Therefore, a literature review on its taxonomy, morphology, ecology, and conservation is presented here. Moreover, field records from the authors, citizen science and the existing literature provide an updated geographic distribution highlighting its presence within 13 new and 7 historic 10 × 10 km cells. Bioclimatic niche modelling was then applied to explore patterns of habitat suitability and phenotypic variation within N. h. cetti. The geographic distribution of the species was found to be positively correlated with altitude and precipitation values, whereas temperature showed a negative correlation. Taken together, these outcomes may explain the snake's presence, particularly in eastern Sardinia. In addition, analysis of distribution overlap with the competing viperine snake (N. maura) and the urodeles as possible overlooked trophic resources (Speleomantes spp. and Euproctus platycephalus) showed overlaps of 66% and 79%, respectively. Finally, geographical or bioclimatic correlations did not explain phenotypic variation patterns observed in this highly polymorphic taxon. Perspectives on future research to investigate N. h. cetti's decline and support effective conservation measures are discussed.
ABSTRACT
Invasive alien species are one of the main causes of biodiversity loss and ecosystem alteration. Obtaining up-to-date occurrence records and accurate invasion risk maps has become crucial to develop timely and effective management strategies. Unfortunately, gathering and validating distribution data can be labor-intensive and time-consuming, with different data sources unavoidably leading to biases in the results. In this study, we evaluated the performance of a tailored citizen science project compared with other data sources, in mapping the current and potential distribution of Iris pseudacorus, a strong invasive alien plant in Argentina. To do so, we used geographic information systems and ecological niche modeling with Maxent, and compared data from: i) a citizen science tailored project; ii) the Global Biodiversity Information Facility (GBIF); and iii) an exhaustive professional data collection (i.e. field samplings across Argentina, literature and collections review). Results suggest that the citizen science tailored project provided a larger and more diversified amount of data compared to the other sources. All data-sources showed good performance in the ecological niche models, however, data from the tailored citizen science project predicted a greater suitable area, including regions not yet reported. This allowed us to better identify critical and vulnerable areas, where management and prevention strategies are necessary. Professional data provided more reports in non-urban areas, whereas citizen science based data sources (i.e. GBIF and the citizen science project conducted in this study) reported more sites in urban areas, which indicates that different data-sources are complementary and there is a big potential in combining methods. We encourage the use of tailored citizen science campaigns to gather a more diverse amount of data, generating better knowledge about aquatic invasive species and helping decision-making in ecosystem management.