Okada Kensuke, Suzaki Yû, Okada Yasukazu, Miyatake Takahisa
Laboratory of Evolutionary Ecology, Graduate School of Environmental Science, Okayama University, Tsushima-naka 111, Okayama 700-8530, Japan.
Zoolog Sci. 2011 Sep;28(9):659-63. doi: 10.2108/zsj.28.659.
Males of the bean bug species Riptortus pedestris possess larger hindlegs than females. Observations of male-male interactions showed that the enlarged hindlegs are used as weapons in male fights, and that males with larger hindlegs win fights more frequently. Morphological analysis based on the positive allometry test showed that the femora of larger males are relatively bigger than those of smaller males, but femora of larger females are not relatively larger than those of smaller females. These results suggest that sexual selection in R. pedestris favors larger hindlegs for male fighting. In addition, the thorax and abdomen lengths were larger in the male than in the female. The males often lift their abdomen with their back to the opponent for displays against an opponent. As a result, abdominal size may be under stronger selection in the male than in the female, as for the exaggerated hindlegs.
豆蝽（Riptortus pedestris）雄性的后腿比雌性的更大。对雄性之间互动的观察表明，增大的后腿在雄性争斗中被用作武器，后腿较大的雄性更频繁地赢得争斗。基于正向异速生长测试的形态学分析表明，体型较大的雄性的股骨相对比体型较小的雄性的股骨更大，但体型较大的雌性的股骨并不比体型较小的雌性的股骨相对更大。这些结果表明，豆蝽的性选择有利于雄性争斗中更大的后腿。此外，雄性的胸部和腹部长度比雌性的更大。雄性经常将腹部抬起，背向对手以向对手展示。因此，与夸张的后腿一样，腹部大小在雄性中可能比在雌性中受到更强的选择。
