FIGURE 6.

Constructive traits in Astyanax mexicanus cavefish. (a and b) Superficial neuromast number and diameter (insets) is increased in cavefish relative to surface fish (a). (Reprinted with permission from Ref 88. Copyright 2010 Elsevier Limited). (c) Differences in feeding posture behavior in surface fish and cavefish. (Reprinted with permission from Ref 90. Copyright 2005 Oxford University Press). (d–g) Cavefish embryos (e) have a larger mouth (o) than surface fish (d). The mouth is encircled by shhA expression (d and e). Later in development (f and g), shhA expression is attenuated to tooth germs (downward arrowheads) and developing taste buds (upward arrowheads). (h–k) Cavefish larvae (i) show increased jaw span (double headed arrows) and anti-calretinin-stained taste buds (arrowheads) on their lips (k) relative to surface fish (h and j). (l and m) Overexpression of shhA by mRNA injection into cavefish embryos causes the formation of a large gaping mouth with excessive taste bud development. (l) Surface fish control and (m) shhA-injected cavefish. (n and o) Conditional heat shock shhA overexpression at the tailbud stage (n) but not at 1 dpf (o) induces eye degeneration, forebrain enlargement, and a larger mouth with more taste buds (not shown) in surface fish larvae. (Reprinted with permission from Ref 91. Copyright 2009 Elsevier Limited)