We studied functional habitat connectivity for Natrix helvetica cetti, a rare and endangered island endemic taxon with a highly fragmented range on Sardinia. Using the habitat suitability model recently developed for this species as input, we applied circuit-theory based connectivity analyses in Julia, combining pairwise runs among all known occurrence localities with an omnidirectional analysis independent of focal nodes. Both approaches converged in identifying the eastern mountain chain as the main connectivity backbone, with a particularly strong corridor linking the Sarrabus reliefs in the south-east to the Barbagia region and, more weakly, to the Monte Limbara area in the north. Additionally, fainter routes were detected along the Iglesiente ranges in south-western Sardinia. Pinch point extraction based on the 95th percentile further identified the main priority connectivity corridors along this eastern backbone. The highest current flow generally connected areas previously predicted to have high habitat suitability, and also highlighted sectors with no confirmed records, suggesting priorities for targeted surveys. Of the identified priority areas, only about 50% fell within protected areas in Circuitscape, whereas this proportion increased to 65% in Omniscape. Our results indicate that corridors in eastern Sardinia are likely to be crucial for maintaining gene flow and long-term persistence of N. h. cetti and provide a spatial basis for integrating this island-restricted reptile into regional connectivity planning and future genetic and health assessments.
\n","language":"eng","license":{"name":"Creative Commons Attribution 4.0","short_name":"CC BY 4.0","text":"Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.\n\nNo additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.","url":"https://creativecommons.org/licenses/by/4.0"},"keywords":[{"word":"Circuit theory"},{"word":"Connectivity models"},{"word":"ecological modelling"},{"word":"landscape connectivity"},{"word":"Natrix helvetica cetti"},{"word":"Sardinia"}],"section":"Articles","is_remote":true,"remote_url":"https://escholarship.org/uc/item/6176s9p2","frozenauthors":[{"first_name":"Luca","middle_name":"","last_name":"Colla","name_suffix":"","institution":"Ethology unit, Departement of biology, University of Pisa, via Volta 6, 56126 Pisa, Italy","department":""},{"first_name":"Matteo Riccardo","middle_name":"","last_name":"Di Nicola","name_suffix":"","institution":"Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, 10154 Torino","department":"Genetics and genomics"}],"date_submitted":"2026-01-07T21:18:00.788000+06:00","date_accepted":"2026-03-17T14:25:15.694982+06:00","date_published":"2026-03-24T20:43:00+06:00","render_galley":{"label":"PDF","type":"pdf","path":"https://journalpub.escholarship.org/biogeographia/article/61984/galley/49124/download/"},"galleys":[{"label":"PDF","type":"pdf","path":"https://journalpub.escholarship.org/biogeographia/article/61984/galley/49124/download/"}]}