1 INTRODUCTION Within species, individual differences (inter-individual variation) are necessary for selection to act (Darwin, 1859) while individual plasticity (i.e. intra-individual variation) may buffer against selection (West-Eberhard, 2003). Understanding causes and consequences of intraspecific variation at the individual, population and species level has consequently attracted much interest (Dall et al., 2012; Dochtermann et al., 2019; Magurran et al., 1998; Sih et al., 2004).
