title: Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation.
abstract: Exposing organisms to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against the two stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress. Thus, cross-tolerance to these physiologically similar stressors could have been positively selected in insects of these regions. We used adults of the saline water beetlesEnochrus jesusarribasi(Hydrophilidae) andNebrioporus baeticus(Dytiscidae) to test cross-tolerance responses to desiccation and salinity. In independent laboratory experiments, we evaluated the effects of (i) salinity stress on the subsequent resistance to desiccation and (ii) desiccation stress (rapid and slow dehydration) on the subsequent tolerance to salinity. Survival, water loss and haemolymph osmolality were measured. Exposure to stressful salinity improved water control under subsequent desiccation stress in both species, with a clear cross-tolerance (enhanced performance) inN. baeticusIn contrast, general negative effects on performance were found under the inverse stress sequence. The rapid and slow dehydration produced different water loss and haemolymph osmolality dynamics that were reflected in different survival patterns. Our finding of cross-tolerance to salinity and desiccation in ecologically similar species from distant lineages, together with parallel responses between salinity and thermal stress previously found in several aquatic taxa, highlights the central role of adaption to salinity and co-occurring stressors in arid inland waters, having important implications for the species' persistence under climate change.
authors.affiliation: Department of Ecology and Hydrology, University of Murcia, 30100 Murcia, Spain susana.pallares@um.es.
authors.forename: Susana
authors.identifier: 0000-0001-8677-7475
authors.initials: S
authors.lastname: Pallarés
authors.affiliation: Department of Ecology and Hydrology, University of Murcia, 30100 Murcia, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Botella-Cruz
authors.affiliation: Department of Life Sciences, Natural History Museum London, London SW7 5BD, UK.|Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.|Island Ecology and Evolution Research Group, IPNA-CSIC, 38206 La Laguna, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Arribas
authors.affiliation: Department of Ecology and Hydrology, University of Murcia, 30100 Murcia, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Millán
authors.affiliation: Department of Ecology and Hydrology, University of Murcia, 30100 Murcia, Spain.
authors.forename: Josefa
authors.initials: J
authors.lastname: Velasco
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D003890:Desiccation; D006458:Hemolymph / Q000502:physiology; D009997:Osmotic Pressure; D054712:Salinity; D055049:Salt Tolerance; D013312:Stress, Physiological
keywords: Beetles; Drought; Homeostasis; Inland waters; Osmotic stress; Water balance