Raghuram Hanumanthan, Deb Rittik, Nandi Diptarup, Balakrishnan Rohini
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India Post graduate and Research Department of Zoology, The American College, Madurai 625 002, India.
Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
Proc Biol Sci. 2015 Jan 7;282(1798):20142319. doi: 10.1098/rspb.2014.2319.
Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females.
发出引人注目的求偶吸引信号的雄性动物，常常面临着被窃听的捕食者捕食的高风险。此类物种的雌性通常会寻找发出信号的雄性，而它们较高的活动能力也可能使它们处于危险之中。在利用远距离信号寻找配偶的背景下，雄性和雌性所面临的相对捕食风险很少得到研究。在本研究中，我们通过饮食分析和行为实验相结合的方法表明，不发出声音信号的螽斯雌性，比发出叫声的雄性，面临来自主要蝙蝠捕食者大耳假吸血蝠的捕食风险更高。在大耳假吸血蝠栖息地下方被捕杀的残骸中，雌性螽斯的数量比雄性多得多。使用螽斯叫声进行的回放实验表明，总体而言，在所有试验中，只有约三分之一的试验中蝙蝠会接近雄性的叫声，而被拴住飞行的螽斯总是会被接近并遭到攻击。我们的研究结果对以下观点提出了质疑，即包括被捕食风险在内的寻找配偶的必要代价，发出信号的雄性比寻找配偶的雌性更高。
