This study was funded by FEDER funds through the Operational Programme for Competitiveness Factors- COMPETE and by National Funds through FCT – Foundation for Science and Technology under the PTDC/BIA-EVF/113805/2009 and FCOMP-01-0124-FEDER-014272. RF is financed by FCT under the Programa Operacional Potencial Humano – Quadro de Referencia Estrategico Nacional from the European Social Fund and the Portuguese Ministerio da Educacao e Ciencia through the postdoctoral fellowship SFRH/BPD/89313/2012. JG is currently supported by a Xunta de Galicia postdoctoral fellowship (Modalidade B).