3D landscape reorganization in response to feeding preferences adaptation in the youngest split Gymnocypris fish.

Divergence in feeding preference is one of the main mechanisms that lead to the emergence of new species.However,little is known about the underlying genetic mechanism of feeding preference adap-tation,especially in the three-dimensional(3D)chromatin organiza-tion regulation.Gymnocypris eckloni scoliostomus(GS)and G.eckloni eckloni(GE)are two sister species of G.eckloni(Cyprinidae:Schizothoracinae:Gymnocypris),both of which are distributed in the Lake Sunmcuo on the Qinghai-Tibet Plateau,China(Zhao et al.,2009).Although GS and GE split only about 57,000 years ago(Zhao et al.,2009),they evolved different feeding preferences and showed significant adaptive divergence in the morphology and func-tion of feeding organs.GS has a terminal or superior mouth with a more oblique and deeply arched mouth cleft and mainly feeds on plankton.By contrast,GE has a subterminal mouth without a horny ridge at the inner margin of the lower jaw and feeds on plankton,zoo-benthos,algae,hydrophytes,and small fish(Zhao et al.,2009).