Acknowledgements

We are grateful to the following people who assisted with fieldwork: Raul Molleda, Carmen Soria, Daniel Fernandez, Pedro Alonso, Juan Tomas Alcalde, Xavier Puig and Maria Mas, Jesús Nogueras and Sonia Sánchez. We also thank Jorge Mederos for his help in designing the arthropod sampling and functional classification, and Juan Luis García-Mudarra for his assistance with laboratory work and comments on the manuscript. Permits to carry out the fieldwork were provided by the administrations of Junta de Andalucia, Gobierno de La Rioja and Cantabria, and Junta de Castilla y León. RNF was funded through a School of Biological Science studentship at the University of Southampton. OR was funded through a Natural Environment Research Council Independent Research Fellowship (NE/M018660/1). Sampling in Jaen was funded by the MICINN project (CGL 2012-38610).