Intraspecific variation in animal mating signals: a test of Mayr's conjecture

Mayr proposed that the stringency of stabilizing selection on animal mating signals is context-dependent: in species lacking sympatric congeners, relaxed selection pressure would afford greater intraspecific variability. This idea has rarely (if ever) been directly tested. Here, I evaluate Mayr’s conjecture using a comprehensive dataset on acoustic mating signals from 39 taxa (33 named species and 6 unnamed lineages) of North American Gryllus field crickets. In doing so, I distinguish between two distinct functions of mating signal components: recognition versus persuasion. Contrary to Mayr’s prediction, intraspecific variation in recognition mating signals did not increase in species with fewer or no sympatric congeners. Stabilizing selection on recognition traits appears to be maintained across both isolated and sympatric populations, possibly due to selection for efficient intraspecific communication—aligning with some aspects of Paterson’s “Specific Mate Recognition System” model. Persuasion traits, on the other hand, show elevated levels of variation consistent with directional sexual selection promoting condition dependence. Together these results reveal the ubiquity of stabilizing selection on recognition traits when at evolutionary equilibrium, and the critical importance of distinguishing between recognition and persuasion functions of animal mating signals.

迈尔（Mayr）提出，针对动物交配信号的稳定选择（stabilizing selection）的严格程度具有情境依赖性：在缺乏同域近缘种（sympatric congeners）的类群中，选择压力的松弛将带来更高的种内变异（intraspecific variability）。这一假说极少（即便曾有尝试）被直接验证。
本研究利用涵盖北美蟋蟀属（Gryllus）田野蟋蟀39个类群（33个已命名物种与6个未命名支系）的声学交配信号（acoustic mating signals）综合数据集，对迈尔的猜想进行了评估。研究过程中，我们区分了交配信号组分的两种截然不同的功能：识别功能与说服功能。
与迈尔的预测相悖，当同域近缘种更少或不存在时，识别型交配信号的种内变异并未出现升高。稳定选择对识别性状的维持似乎贯穿了隔离种群与同域种群，这可能源于对高效种内交流的选择——这与帕特森（Paterson）的“特定配偶识别系统（Specific Mate Recognition System）”模型的部分观点相契合。
说服型性状则表现出更高水平的变异，这与推动条件依赖性的定向性选择（directional sexual selection）的作用模式相符。综上，本研究结果揭示了在进化平衡状态下，稳定选择普遍存在于识别性状之中，同时也凸显了区分动物交配信号的识别与说服功能的关键重要性。