“…Physiological-behavioral trait associations are commonly referred to as stress coping styles [Koolhaas et al, 1999], while consistent individual variations in behavior across situations have been denoted behavioral syndromes [Sih et al, 2004a, b], animal personalities [Gosling, 2001], temperament [Réale et al, 2007], or a shyness-boldness continuum [Wilson et al, 1994;Sneddon, 2003]. Despite a certain lack of consensus in terminology, revealing the ultimate and proximate mechanisms behind these analogues of human personality may add to the knowledge within diverse fields such as evolutionary ecology, animal husbandry, and biomedicine [Korte et al, 2005;Øverli et al, 2007;Zozulya et al, 2008;Dingemanse and Wolf, 2010;Koolhaas et al, 2010;Stamps and Groothuis, 2010;Conrad et al, 2011;Castanheira et al, 2015;Duckworth, 2015;Hau and Goymann, 2015;Sih et al, 2015]. Among the questions raised are: via what mechanisms are trait correlations inherited, which circumstances benefit different complex phenotypes, and what are the costs and benefits of the limited plasticity imposed by fixed trait associations?…”