日本蚁蛛（蜘蛛目：跳蛛科）加长螯肢在性选择中的作用

The role of elongated male chelicerae in sexual selection of an ant-Like jumping spider Myrmarachne japonica

雄性夸张的身体结构通常在雌性择偶中作为装饰品，在雄性竞争中作为武器。跳蛛科蚁蛛属的雄性螯肢存在明显的性二态特征，雄性通常具有比雌雄更长的螯肢。一般认为蚁蛛雄性加长的螯肢被用于性选择，即雄性竞争或雌性择偶或两者都有。然而，这个假设未得到实验验证。本文以日本蚁蛛（Myrmarachne japonica）为研究对象，在实验室利用雄性竞争和雌性择偶实验研究雄性加长螯肢在性选择中的作用来验证这个假设。当对两个雄性蚁蛛作出选择时，日本雌性蚁蛛更偏爱螯肢更长的雄性；然而，在雄性竞争试验中，更长螯肢的雄性与更短螯肢的雄性竞争结果无显著差异。因此，我们认为日本蚁蛛加长的雄性螯肢可能主要用于雌蛛的择偶。

：Exaggerated male structures often serve as ornaments in female mate-choice or armaments （weapons） in male-male competition. Spiders of the ant-like jumping spider genus Myrmarachne （Araneae： Salticidae） exhibit marked sexual dimorphism in cheliceral size where males usually have longer chelicerae than females. It is assumed that the elongated male chelicerae of Myrmarachne spiders are used in sexual selection, i.e., female mate-choice and/or male-male competition. However, this hypothesis remains untested empirically. In this study, using Myrmarachne japonica as a model system, we tested this hypothesis by examining the role of the elongated male chelicerae in female mate-choice and male-male competition in the laboratory. When given a choice between two males, M. japonica females showed a strong preference for males with longer chelicerae over males with shorter chelicerae. In male-male contests, however, M. japonica males with longer chelicerae won the contests as often as males with shorter chelicerae did. We conclude that the elongated male chelicerae may play an important role in female mate-choice but not in male-male competition in M. japonica.