Fig. 7
From: The loss of flight in ant workers enabled an evolutionary redesign of the thorax for ground labour
Distributions of fibre angles for the dorsal petiole muscles (top IA1; bottom IA2; see Additional file 8) differ between Euponera sikorae queen (grey) and worker (red). Fibres with an angle of 0° contract in the same direction as the force exerted by the muscle, hence lower angles mean more efficient fibres. Dashed line indicates mean angle. According to Mann-Whitney rank sum tests for non-normally distributed data, attachment angles in IA1 are significantly lower in worker than in the queen (W = 27,911, p < 0.05). There is no significant difference in distribution of angles between worker and queen in IA2 (W = 18,231, p = 0.33)