Fig. 2. (A) Orientation angles of sandhoppers subjected to an artificial L:D cycle (15h:9h) corresponding to the natural cycle in phase and duration. (B) Orientation angles of individuals subjected to an artificial L:D cycle (15h:9h) inverted with respect to the natural cycle: the sandhoppers were released during their subjective night. (C) Orientation angles of sandhoppers subjected to an artificial 4h:20h L:D cycle; and (D) to an artificial 20h:4h inverted L:D cycle. The diagrams represent the relationship between the mean angle resulting from each release (filled circles) and time of day. White and black bars represent the natural or subjective hours of light and dark, respectively. a, expected direction towards land (i.e. yL) for differential compensation; b, expected yL according to the model of compensation proposed in this study; c, interpolation of the data. In C, curve d represents the expected direction according to the proposed model in the case of clock-shifting affecting subjective noon (clockwise shifting of 6h and 17 min). Line e indicates the same thing in the case of differential compensation. In B and D, the line for yL based on differential compensation is not represented since we do not know the curve of the sun at night. The equations of the regressions are also given.

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