Morris Glenn K, Hall Aaron M, Römer Heiner
Department of Biology, University of Toronto at Mississauga, Mississauga, Canada.
, Denver, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2018 Apr;204(4):339-351. doi: 10.1007/s00359-018-1250-8. Epub 2018 Feb 13.
Males of the katydid Sphagniana sphagnorum form calling aggregations in boreal sphagnum bogs to attract mates. They broadcast frequency-modulated (FM) songs in steady series, each song comprised of two wing-stroking modes that alternate audio and ultrasonic spectra. NN analysis of three populations found mean distances between 5.1 and 8.4 m, but failed to find spacing regularity: in one males spaced randomly, in another they were clumped, but within the clumps spaced at random. We tested a mechanism for maintaining inter-male distances by playback of conspecific song to resident males and analysing song interactions between neighbouring males in the field. The results indicate that the song rate is an important cue for males. Information coded in song rates is confounded by variation in bog temperatures and by the linear correlation of song rates with temperature. The ultrasonic and audio spectral modes suffer different excess attenuation: the ultrasonic mode is favoured at shorter distances (< 6 m), the audio mode at longer distances (> 6 m), supporting a hypothesized function in distance estimation. Another katydid, Conocephalus fasciatus, shares habitat with S. sphagnorum and could mask its ultrasonic mode; however, mapping of both species indicate the spacing of S. sphagnorum is unaffected by the sympatric species.
泥炭藓叶螽的雄性个体在北方泥炭藓沼泽中形成求偶聚集区以吸引配偶。它们以稳定的序列发出调频（FM）歌声，每首歌由两种交替出现音频和超声波频谱的翅膀挥动模式组成。对三个种群的最近邻分析发现，个体间平均距离在5.1至8.4米之间，但未发现间距规律：在一个种群中雄性个体随机分布，在另一个种群中它们聚集在一起，但在聚集体内部则随机分布。我们通过向驻留雄性个体回放同种歌声并分析野外相邻雄性个体之间的歌声互动，来测试一种维持雄性个体间距离的机制。结果表明，歌声速率是雄性个体的一个重要线索。歌声速率中编码的信息因沼泽温度的变化以及歌声速率与温度的线性相关性而变得复杂。超声波和音频频谱模式遭受不同程度的额外衰减：超声波模式在较短距离（<6米）时更受青睐，音频模式在较长距离（>6米）时更受青睐，这支持了其在距离估计方面的假设功能。另一种螽斯，条纹草螽，与泥炭藓叶螽共享栖息地，可能会掩盖其超声波模式；然而，对这两个物种的分布测绘表明，泥炭藓叶螽的分布间距不受同域物种的影响。
