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1. The white-clawed crayfish (Austropotamobius pallipes) is globally endangered due to the impacts of habitat modification and fragmentation, water pollution, climate change, and invasive species, particularly the signal crayfish (Pacifastacus leniusculus). These pressures have caused the decline of A. pallipes populations in Europe, demonstrating the importance of predicting the species' potential distribution under current and future conditions. Focusing on the watercourses of mainland France, we aimed to identify suitable areas for A. pallipes to guide the conservation of current populations and future introduction actions or protection measures.2. We applied ecological niche modelling to model the potential distribution of both A. pallipes and P. leniusculus and identified locations suitable for A. pallipes only.We also assessed the potential distribution of the species under two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, respectively describing low-warming and high-warming conditions.3. We found that A. pallipes and P. leniusculus exploit equivalent niches in France.Despite this, under current conditions, about 5% of the study area simultaneously records a high suitability for A. pallipes and a low suitability for P. leniusculus and is therefore of significant conservation interest. This percentage remains relatively stable under RCP 2.6 for 2050 and 2100, but decreases to 2% under RCP 8.5 for 2100. 4. Ecological niche modelling can supply crucial guidance for conservation actions aimed at protecting endangered species at a national scale by identifying sites most suitable for protection and sites where climate change and invasive species constitute a threat. K E Y W O R D S ecological niche modelling, habitat suitability, climate change, conservation, niche overlap | 305 PRÉAU et Al. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Préau C, Nadeau I, Sellier Y, et al. Niche modelling to guide conservation actions in France for the endangered crayfish Austropotamobius pallipes in relation to the invasive Pacifastacus leniusculus. Freshwater Biology.

Climate and land use/land cover (LULC) change are two major global change factors driving shifts in the location of suitable areas for many species. Here, we assessed if a low‐vagility newt, Triturus marmoratus, can track displacement of suitable areas by 2100, and tested whether climate or LULC changes are primary drivers of the species’ future distribution. We combined niche modelling with the process‐based model simRShift to improve biological relevance and simulate species dispersal by 2100 under scenarios of climate and LULC changes at high spatial resolution. Our results show that T. marmoratus could lose a significant part of its current French range in the coming decades, and that the range loss will primarily be driven by climate change, with LULC change playing a secondary role. The species seems unlikely to be able to track the northern shift of its suitable habitat as rapidly as required given the rate of climate warming during the 21st century. This is due to insufficient dispersal ability, which is compounded by the magnitude of habitat fragmentation in the human‐dominated landscape. We highlight the need to assess vulnerability and anticipate threats arising from global change even for species that are not currently considered endangered. We identified areas where the species is most likely to occur and be extinct in the future, which can serve as a guide for population monitoring. Our framework can support conservation strategy development by defining ecological corridors that would assist species to track their required habitats in the face of global change.

& francis isselin-nondedeu 3,6Triturus cristatus and Triturus marmoratus are two protected and declining newts occurring in the administrative department of Vienne, in France. They have limited dispersal abilities and rely on the connectivity between habitats and their suitability. In a warming climate, the locations of suitable habitats are expected to change, as is the connectivity. Here, we wondered how climate change might affect shifts in habitat suitability and connectivity of habitat patches, as connectivity is a key element enabling species to realize a potential range shift. We used ecological niche modelling (ENM), combining large-scale climate suitability with local scale, high-resolution habitat features, to identify suitable areas for the two species, under low and high warming scenarios (RCP 2.6 and RCP 8.5). We associated it with connectivity assessment through graph theory. The variable 'small ponds' contributed most to land cover-only ENMs for both species. Projections with climate change scenarios revealed a potential impact of warming on suitable habitat patches for newts, especially for T. cristatus. We observed a decrease in connectivity following a decrease in patch suitability. Our results highlight the important areas for newt habitat connectivity within the study area, and define those potentially threatened by climate warming. We provide information for prioritizing sites for acquisition, protection or restoration, and to advise landscape policies. Our framework is a useful and easily reproducible way to combine global climate requirements of the species with detailed information on species habitats and occurrence when available. open Scientific RepoRtS | (2020) 10:3570 | https://doi.org/10.1038/s41598-020-60479-4www.nature.com/scientificreports www.nature.com/scientificreports/ connected by "edges", which refer to ecological corridors. Landscape graphs can be used to represent ecological networks and to analyse connectivity between habitats, with, for instance, the purpose of prioritizing sites for protection, improving connectivity, or assessing potential effect of an urban development project 19,20 . In this approach, the landscape between habitat patches is represented by a "resistance" or "cost" which estimates the relationships between environmental variables and movement of the considered species 21 . Resistance surfaces can be categorical, with a cost associated with land cover types 22 ; continuous, for example from an output of ENM, where resistance increases when habitat suitability decreases 23,24 ; or binary, assuming that the influence of the matrix on species movement is homogenous between patches 25 . Ziółkowska et al. 26 have compared the efficiency of such resistance surface representation on landscape connectivity assessment and they recommend using continuous resistance surface whenever possible. Using a habitat suitability map from ENM helps to overcome a lack of sufficient data. The use of ENM output is also a way to explore predictions of changes in high habitat su...