ORIGINAL PAPER Desiccation resistance along an aridity gradient in the cactophilic fly Drosophila buzzatii: sex-specific responses to stress Paola L. Sassi • Esteban Hasson Received: 17 May 2012 / Accepted: 22 October 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract Stress resistance characters are valuable tools for the study of acclimation potential, adaptive strategies and biogeographic patterns in species exposed to environ- mental variability. Water stress is a challenge to terrestrial arthropods because of their small size and relatively high area: volume ratio. Fruit flies have been investigated to record adaptive morphological and physiological traits, as well as to test their responses to stressful factors. In this study, we investigate the ability to cope with water stress, by examining variation in desiccation resistance in a species that lives mainly in desert lands. Specifically, we explored the genetic and ecological basis of desiccation resistance in populations of Drosophila buzzatii from Northern Argentina. We used a common garden experiment with desiccation treatments on a number of isofemale lines from four popu- lations along an aridity gradient. Our results revealed significant among-population dif- ferentiation and substantial amounts of genetic variation for desiccation resistance. We also detected significant genotype-by-environment and genotype-by-sex interactions indicative that desiccation resistance responses of the lines assayed were environment- and sex- specific. In addition, we observed clinal variation in female desiccation resistance along gradients of altitude, temperature and humidity; that desiccation resistance is a sexually dimorphic trait, and that sexual dimorphism increased along the aridity and altitudinal gradients. Based on current evidence, we propose that the observed sex-specific responses P. L. Sassi (&) Departamento de Ecologı ´a, Gene ´tica y Evolucio ´n & IEGEBA, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Gu ¨iraldes 2160, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina e-mail: psassi@mendoza-conicet.gob.ar Present Address: P. L. Sassi Grupo de Investigaciones de la Biodiversidad, CONICET, IADIZA, CCT-Mendoza, Av. Ruiz Leal s/n, Parque Gral. San Martı ´n, CC 507 (5500) Mendoza, Argentina E. Hasson Departamento de Ecologı ´a, Gene ´tica y Evolucio ´n & IEGEBA, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Gu ¨iraldes 2160, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina 123 Evol Ecol DOI 10.1007/s10682-012-9616-9