Noun : the bold coloration of some birds.    From Dictionary.com. 

Walsh shows that a complete gradation exists between species which are absolutely unaffected by change of food and cases where "difference of food is accompanied by marked and constant differences, either colorational, or structural, or both, in the larva, pupa and imago states."), most of which was new to me.    From Wordnik.com.  [More Letters of Charles Darwin — Volume 1] Reference