Physiological Entomology (2011) 36, 165–172 DOI: 10.1111/j.1365-3032.2011.00778.x Saline stress tolerance partly matches with habitat preference in ground-living wolf spiders JULIENP ´ ETILLON 1,2 , KEVIN LAMBEETS 3 ,BRUNILDE RACT-MADOUX 1 , PHILIPPE VERNON 4 and D A V I D R E N A U L T 1 1 Universit´ e de Rennes 1, UFR SVE, Rennes Cedex, France, 2 Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerpen, Belgium, 3 Terrestrial Ecology Unit, Ghent University, Ghent, Belgium and 4 Universit´ e de Rennes 1, UMR 6553, France Abstract. Salinity interacts with many physiological functions and therefore probably influences the distribution of terrestrial fauna in tidal flooded salt marshes. The present study tests the hypothesis that the physiological tolerance of stenotopic wolf spiders for saline conditions at least partially determines their occurrence throughout salt-marsh and nonsaline habitats. The duration of survival of three stenotopic wolf spider species (Araneae: Lycosidae) with different habitat preferences is compared in a controlled laboratory experiment. The forest-dwelling Pardosa saltans, the salt-marsh resident Pardosa purbeckensis and its sister species the inland- living Pardosa agrestis are exposed to experimental conditions with different levels of salinity. Individuals (45 males and 20–45 females per treatment) are placed in individual air-tight boxes filled with water-saturated sand. Three levels of salinity are tested: nonsaline (0‰), medium saline (33–35‰) and highly saline (66–70‰). Contents of carbon, hydrogen and nitrogen and the molar ration carbon/nitrogen remain constant over time and do not differ among salinity treatments, indicating that starvation effects on survival, if any, are similar for all treatments. Conversely, body water significantly decreases over time and differs among salinity treatments, in accordance with patterns of survival. Conforming to their habitat preference, the survival of P. saltans and P. agrestis decreases quickly under highly saline conditions. Pardosa purbeckensis, however, has a high survival under both saline and nonsaline conditions. The duration of survival of females is significantly lower than that of males of P. saltans and P. purbeckensis. Durations of survival of ground-living wolf spiders exposed to salinity partly match their habitat distribution but do not explain the restriction of salt-marsh species to saline habitats. Key words. Environmental stress, habitat specialization, interspecific comparison, Pardosa spp., physiological tolerance, salinity. Introduction The distribution of species is not only determined by exter- nal factors such as the direct abiotic environment and biotic constraints, but also by intrinsic conditions, such as the phys- iological state of the species (Spicer & Gaston, 1999). Hence, Correspondence: Julien P´ etillon, Evolutionary Ecology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium. Tel.: +33 223 236851; e-mail: julien.petillon@univ-rennes1.fr species differing in their ecological needs, as reflected by (micro) habitat selection (Dennis et al., 2003), might also differ in their ecophysiological characteristics (DeVito et al., 2004). Additionally, species might adapt to new conditions if changes in life-history traits would benefit their survival over the long term (Stearns, 1992). Salt marshes, comprising intertidal habitats located between terrestrial and marine ecosystems, are prone to rapid changes in salinity, temperature and water depth after tidal floods (P´ etillon et al., 2010a). For that reason, salt marshes are inter- esting model systems for testing relationships between abiotic  2011 The Authors Physiological Entomology  2011 The Royal Entomological Society 165