Rubi Tricia L, Clark David L, Keller Jonathan S, Uetz George W
Department of Ecology, Evolution, and Behavior, University of Minnesota, 1479 Gortner Ave, St. Paul, MN 55108, USA.
Department of Biology, Alma College, 614 Superior St, Alma, MI 48801, USA.
Behav Processes. 2019 May;162:215-220. doi: 10.1016/j.beproc.2018.12.023. Epub 2019 Jan 14.
Signalers must balance the benefits of detection by intended receivers with the costs of detection by eavesdroppers. This trade-off is exemplified by sexual signaling systems, in which signalers experience sexual selection for conspicuousness to mates as well as natural selection for crypsis to predators. In this study, we examined how courtship behavior and body coloration influenced the conspicuousness of males to avian predators in the well-studied brush-legged wolf spider system (Schizocosa ocreata (Hentz)). We focused on three behaviors (courtship, walking, and freezing) and two coloration schemes (natural coloration and idealized background-matching coloration). We presented captive blue jays (Cyanocitta cristata) with video playbacks of male spiders in a presence-absence detection task and characterized conspicuousness by measuring response latency and detectability. We found that any type of motion significantly increased detectability, and that body coloration and behavior interacted to determine detectability while the spiders were in motion. Among spiders in motion, courting spiders were detected faster than walking spiders. Stationary (frozen) spiders, in contrast, were rarely detected. These results illustrate that male S. ocreata can be both highly conspicuous and highly cryptic to avian predators. Thus, while we find that courtship is conspicuous to avian predators in this system, we suggest that behavioral plasticity may mitigate some of the predation costs of the sexual signal.
信号发出者必须在预期接收者进行探测的益处与窃听者进行探测的代价之间找到平衡。这种权衡在性信号系统中得到了体现，在该系统中，信号发出者既要因对配偶显眼而经历性选择，又要因对捕食者保持隐蔽而经历自然选择。在本研究中，我们在研究充分的刷腿狼蛛系统（Schizocosa ocreata (Hentz)）中，研究了求偶行为和体色如何影响雄性对鸟类捕食者的显眼程度。我们聚焦于三种行为（求偶、行走和静止不动）以及两种体色模式（自然体色和理想化的背景匹配体色）。我们在一个存在-缺失探测任务中，向圈养的冠蓝鸦（Cyanocitta cristata）播放雄性蜘蛛的视频回放，并通过测量反应潜伏期和可探测性来表征显眼程度。我们发现，任何类型的运动都会显著提高可探测性，并且在蜘蛛移动时，体色和行为相互作用以决定可探测性。在移动的蜘蛛中，求偶的蜘蛛比行走的蜘蛛被更快地探测到。相比之下，静止不动（冻结）的蜘蛛很少被探测到。这些结果表明，对于鸟类捕食者而言，雄性奥氏狼蛛既可能非常显眼，也可能非常隐蔽。因此，虽然我们发现在这个系统中求偶行为对鸟类捕食者来说是显眼的，但我们认为行为可塑性可能会减轻性信号带来的一些捕食代价。
