 Surface fish (a, b) and cave fish (c, d) differ in many morphological traits, the most prominent being the loss of pigmentation and the loss of eyes in the cave forms. (Image reused with the kind permission from Copyright Clearance Center: Nature Communications.  The cavefish genome reveals candidate genes for eye loss . Suzanne E. McGaugh, Joshua B. Gross, Bronwen Aken, Maryline Blin, Richard Borowsky et al.,© Springer Nature 2014)&amp;nbsp; 