Instituto de Biología, Departamento de Biología Animal, Laboratorio de Fisiología de la Reproducción y Ecología de Peces, Facultad de Ciencias, Universidad de la Republica, Igua 4227, Montevideo, Uruguay.
Unidad de Anatomía, Facultad de Veterinaria, Universidad de la República, Lasplaces 1620, 11600 Montevideo, Uruguay.
J Acoust Soc Am. 2022 Jul;152(1):429. doi: 10.1121/10.0012690.
The male and female southern black drum possess highly specialized, bilateral, striated sonic muscles used in sound production during courtship by males and in the production of disturbance calls by both males and females. Androgen-driven hypertrophy of the sonic muscles in males during the late spring spawning period results in increased growth of sonic muscle mass followed by post-spawning atrophy of sonic muscles. We examined changes in sonic muscle morphology and in the sound characteristics of males and females underlying seasonal changes in sonic muscle mass and muscle contraction as measured by sound production. In males, the sound pressure level increased while sound pulse duration decreased with increasing sonic muscle mass, indicating that sonic muscle fibers contract with greater force and shorter duration during the spawning season. Interpulse interval and the total number of pulses varied seasonally with muscle mass, which suggests that the effects of steroids on male southern black drum sound characteristics are more pronounced peripherally than in the central nervous system. In females, no increase in sonic muscle mass was found, and therefore, a change was not observed in the acoustic variables analyzed. Seasonal sonic muscle hypertrophy in males likely functions as a secondary sexual characteristic that maximizes vocalization amplitude or loudness during the spawning period.
南方黑鲈的雌雄个体都拥有高度特化的双侧横纹声肌，用于求偶时雄性个体发出求爱声，以及雄性和雌性个体发出干扰声。在春季末的繁殖期，雄性个体的雄激素驱动声肌发生肥大，导致声肌质量增加，随后在繁殖后发生声肌萎缩。我们研究了声肌形态的变化，以及雄性和雌性个体的声音特征，这些特征与声肌质量的季节性变化以及通过发声测量的肌肉收缩有关。在雄性个体中，随着声肌质量的增加，声压级增加，而声脉冲持续时间减少，这表明在繁殖季节，声肌纤维以更大的力和更短的持续时间收缩。声脉冲间隔和脉冲总数随肌肉质量季节性变化，这表明类固醇对雄性南方黑鲈声音特征的影响在外周比在中枢神经系统更为明显。在雌性个体中，没有发现声肌质量的增加，因此，在分析的声学变量中没有观察到变化。雄性个体季节性的声肌肥大可能是一种次要的性特征，在繁殖期最大限度地增加发声的幅度或响度。
