Suitable habitats redistribution for the European pond turtle (Emys orbicularis) lineages under future climate change

Emys orbicularis is a freshwater ectotherm turtle sensitive to climatic variation and landscape quality. Because this species is structured into several evolutionary lineages with distinct biogeographic histories, modelling it as a single unit may obscure lineage-specific responses to climate change. Here, we assessed how future climate change may reshape the distribution of its main European lineages by integrating lineage-level, dispersal limitation, and landscape quality into ensemble ecological niche models. We analysed five major lineages and split E. o. orbicularis II into western and eastern components. Climatic niche differentiation was quantified, and future distributions were projected for 2041–2070 and 2071–2100 under two SSP scenarios (SSP1-2.6, SSP5-8.5) and two GCMs (GFDL-ESM4, UKESM1-0-LL). Projections were constrained by a maximum dispersal rate of 5 km per year and filtered by land-cover–based landscape quality. Climatic niches differed among lineages, with significant overlap detected only between E. o. orbicularis I and II E . Climate-only projections showed discrepancies between the lineages and GCM, with pronounced losses of suitable areas within the range for E. o. occidentalis and E. o. galloitalica and more remaining suitable areas for E. o. orbicularis I and II lineages. Considering landscape quality consistently reduced effective suitability: four lineages were largely associated with low-quality landscapes, whereas E. o. orbicularis II W and orbicularis I kept higher proportions of climatically suitable habitat in moderate to favorable landscapes quality. Lineage-level models that integrate landscape and dispersal constraints provide more biologically realistic projections and help prioritize lineage-specific refugia, and conservation actions under climate change.