Setoguchi Shiori, Kudo Ayumi, Takanashi Takuma, Ishikawa Yukio, Matsuo Takashi
Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Department of Forest Entomology, Forestry and Forest Products Research Institute, Matsuno-sato 1, Tsukuba, Ibaraki 305-8687, Japan.
Proc Biol Sci. 2015 Nov 7;282(1818):20151377. doi: 10.1098/rspb.2015.1377.
Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform 'leg vibration', in which a male vibrates the female's body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to 'rubbing', which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration.
许多动物物种中都观察到周围环境（如同种雄性的存在）会诱导替代交配策略。卫星行为就是一个显著的例子，寄生雄性利用其他雄性的生殖投资。然而，尽管寄生交配策略很常见，但雄性改变求偶行为作为对抗寄生对手的反制策略的例子却很少见。果蝇Drosophila prolongata在前腿上表现出明显的两性异形。在求偶时，D. prolongata的雄性会进行“腿部振动”，即用其增大的前腿振动雌性的身体。在本研究中，我们发现腿部振动增加了雌性的接受度，但同时也增加了雌性被竞争对手雄性拦截的风险。因此，在有竞争对手的情况下，D. prolongata的雄性将其求偶行为从腿部振动转变为“摩擦”，这种行为较不易受到竞争对手雄性的干扰。这些结果表明，D. prolongata的雄性会调整其求偶行为，以规避腿部振动所带来的依赖社会环境的风险。
