Data from: Exploring the hidden landscape of female preferences for complex signals

A major challenge in evolutionary biology is explaining the origins of complex phenotypic diversity. In animal communication, complex signals may evolve from simpler signals because novel signal elements exploit pre-existing biases in receivers’ sensory systems. Investigating the shape of female preference functions for novel signal characteristics is a powerful, but underutilized, method to describe the adaptive landscape potentially guiding complex signal evolution. We measured female preference functions for characteristics of acoustic appendages added to male calling songs in the grasshopper Chorthippus biguttulus, which naturally produces only simple songs. We discovered both hidden preferences for and biases against novel complex songs, and identified rules governing song attractiveness based on multiple characteristics of both the base song and appendage. The appendage’s temporal position and duration were especially important: long appendages preceding the song often made songs less attractive, while following appendages were neutral or weakly attractive. Appendages had stronger effects on songs of shorter duration, but did not restore the attractiveness of very unattractive songs. We conclude that sensory biases favor, within predictable limits, the evolution of complex songs in grasshoppers. The function-valued approach is an important tool in determining the generality of these limits in other taxa and signaling modalities.进化生物学（evolutionary biology）领域的一大核心挑战，在于阐释复杂表型（phenotype）多样性的起源。在动物通讯（animal communication）中，复杂信号或可由简单信号演化而来——因为新型信号元件（signal element）可利用接收方感官系统中预先存在的感知偏向（sensory bias）。针对新型信号特征探究雌性偏好函数（female preference functions）的形态，是一种强大却未得到充分利用的方法，可用于描述潜在驱动复杂信号演化的适应性景观（adaptive landscape）。本研究以仅能自然产生简单鸣唱的大翅雏蝗（Chorthippus biguttulus）为对象，测量了其雄性鸣唱中附加声学附属特征时的雌性偏好函数。研究发现，该物种既存在对新型复杂鸣唱的隐性偏好，也存在对其的排斥偏向；同时基于基础鸣唱与附属结构的多项特征，明确了调控鸣唱吸引力的规则。附属结构的时序位置与时长尤为关键：鸣唱前添加的长附属结构通常会降低鸣唱吸引力，而鸣唱后附加的附属结构则对吸引力无显著影响，或仅产生微弱的正向作用。附属结构对时长较短的鸣唱影响更强，但无法提升吸引力极低的鸣唱的吸引力水平。综上，本研究认为，在可预测的边界范围内，感知偏向会推动蝗虫复杂鸣唱的演化。函数值方法（function-valued approach）是在其他类群（taxa）与信号模态（signaling modalities）中验证这些边界普遍性的重要工具。