Fig. 4

The evolutionary trajectory of the three simplified types in Triplophysa. a Time-calibrated Bayesian species tree from the *BEAST analysis. Circles on the tips indicate three simplified types, and pie charts at ancestral nodes represent their relative ML supports. The triangle with arrow indicates the direction with unequivocal transition numbers (average). N1-N4 denote four nodes. b Three characteristics of Triplophysa. Lower jaw: broadened, sharp and uncovered by lips (rose red); spoon-like, sharp and uncovered by lips (black red); spoon-like, blunt and covered by lips (gray). PCAB (posterior chamber of air bladder): developed (gray) and degenerated (rose red). Intestine: screw shape (rose red) and zig-zag shape (gray). Details are depicted in Additional file 1: Figure S5. c Climatic events (modified from Favre et al. [17] and Zachos et al. [18]): the red dotted line denotes the major global temperature trends; tildes (∼) represent the Quaternary climate oscillations