Bazterrica Florencia, Mayol Juan Mateo, Vignetta Estefano, Flores Vladimir, Rapacioli Melina
Grupo Interdisciplinario de Biología Teórica, Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Universidad Favaloro, INECO, CONICET, Buenos Aires, Argentina.
PLoS One. 2025 Sep 3;20(9):e0330466. doi: 10.1371/journal.pone.0330466. eCollection 2025.
The present paper analyzes the sounds emitted by pre-hatching chicks, focusing on those named as "clicks," which are thought to mediate pre-hatching social interactions and hatching synchronization. Representative acoustic signals were analyzed under three incubation conditions: (1) isolated pre-hatching chicks (n = 13), (2) pre-hatching chicks in contact with others of the same age (n = 14), and (3) pre-hatching chicks in contact with other of different age (n = 10 for each group: leader and follower). Customized MATLAB software was developed to (a) identify and isolate clicks from other recorded sounds, (b) represent them as temporal series of stochastic point processes, and (c) determine whether click emission dynamics resembled white noise or exhibited characteristics of informative signals. Mathematical methods were applied to analyze (a) temporal dynamics, (b) clustering patterns (via hierarchical clustering and log-log scaling), and (c) scaling properties (via power spectral density analysis) of clicks under each condition. The results reveal developmental-dependent changes in click temporal patterns. As hatching approaches, clicks evolve from isolated events to highly organized hierarchical clusters. Contacting chicks displayed greater temporal organization than isolated ones. Significantly, contact with more advanced chicks accelerated click dynamics in less developed embryos, while older embryos showed a slight delay, suggesting reciprocal social interactions. Spectral analysis revealed long-range correlations consistent with fractional Gaussian noise. These findings confirm that click sequences (a) exhibit physical characteristics of informative signals, (b) function as communication signals, and (c) align developmental processes among pre-hatching chicks. The study underscores the value of fractal analysis in describing physiological signals and expands our understanding of prenatal social interactions. The results suggest that acoustic signals may influence both hatching coordination and central nervous system development. This work provides insight into the evolutionary advantage of embryo communication and highlights the importance of studying how environmental disruptions may affect these critical prenatal processes.
本文分析了孵化前雏鸡发出的声音，重点关注那些被称为“滴答声”的声音，这些声音被认为在孵化前的社会互动和孵化同步中起媒介作用。在三种孵化条件下分析了代表性声学信号：(1) 隔离的孵化前雏鸡（n = 13），(2) 与同龄其他雏鸡接触的孵化前雏鸡（n = 14），以及(3) 与不同年龄其他雏鸡接触的孵化前雏鸡（每组n = 10：领导者和跟随者）。开发了定制的MATLAB软件，用于(a) 从其他记录的声音中识别和分离滴答声，(b) 将它们表示为随机点过程的时间序列，以及(c) 确定滴答声发射动态是类似于白噪声还是表现出信息性信号的特征。应用数学方法分析每种条件下滴答声的(a) 时间动态、(b) 聚类模式（通过层次聚类和对数-对数缩放）以及(c) 缩放特性（通过功率谱密度分析）。结果揭示了滴答声时间模式中与发育相关的变化。随着孵化临近，滴答声从孤立事件演变为高度有组织的层次聚类。接触的雏鸡比隔离的雏鸡表现出更大的时间组织性。值得注意的是，与更高级的雏鸡接触加速了发育较不成熟胚胎中的滴答声动态，而较老的胚胎则略有延迟，这表明存在相互的社会互动。频谱分析揭示了与分数高斯噪声一致的长程相关性。这些发现证实，滴答声序列(a) 表现出信息性信号的物理特征，(b) 作为通信信号起作用，以及(c) 使孵化前雏鸡之间的发育过程同步。该研究强调了分形分析在描述生理信号方面的价值，并扩展了我们对产前社会互动的理解。结果表明，声学信号可能影响孵化协调和中枢神经系统发育。这项工作为胚胎通信的进化优势提供了见解，并突出了研究环境干扰如何影响这些关键产前过程的重要性。
