Pace Daniela Silvia, Tumino Carla, Silvestri Margherita, Giacomini Giancarlo, Pedrazzi Giulia, Pavan Gianni, Papale Elena, Ceraulo Maria, Buscaino Giuseppa, Ardizzone Giandomenico
Department of Environmental Biology, Sapienza University of Rome, 00185 Rome, Italy.
Department of Environmental and Evolutionary Sciences, University Austral of Chile, Valdivia 5090000, Chile.
Biology (Basel). 2022 Feb 25;11(3):367. doi: 10.3390/biology11030367.
Acoustic sequences are commonly observed in many animal taxa. The vast vocal repertoire of common bottlenose dolphins () also includes sequences of multi-unit rhythmic signals called bray-call which are still poorly documented, both functionally and geographically. This study aimed to (1) describe, classify, and characterize series of bray-call recorded in two sites of the Mediterranean basin (Rome-Tyrrhenian Sea and Mazara del Vallo-Strait of Sicily) and (2) investigate for the existence of possible geographic differences. The acoustic analysis identified 13 different sequence types, only two detected in both study areas. The Sørensen-Dice index revealed a low degree of similarity between the sequence repertoire of the two common bottlenose dolphin sub-populations, with the Tyrrhenian being more diversified and complex than the Sicilian one. The acoustic parameters also showed variability between the study area. Different variants of the main acoustic elements composing the bray-call sequences were detected in the Tyrrhenian Sea only. The Markov-chain model demonstrated that the transition probability between acoustic elements is not uniform, with specific combinations of elements having a higher probability of occurrence. These new findings on common bottlenose dolphin bray-call sequences highlight the structural complexity of these vocalizations and suggest addressing future research on the context of emissions and the possible function(s) of such acoustic arrangements.
声学序列在许多动物类群中普遍存在。宽吻海豚（）丰富的发声库中还包括一系列被称为“ Bray-call”的多单元节奏信号序列，在功能和地理分布方面，这些序列的记录仍然很少。本研究旨在：（1）描述、分类和表征在地中海盆地两个地点（罗马 - 第勒尼安海和西西里海峡的马扎拉德尔瓦洛）记录的 Bray-call 序列；（2）调查是否存在可能的地理差异。声学分析确定了 13 种不同的序列类型，两个研究区域仅检测到两种。索伦森 - 迪西指数显示，两个宽吻海豚亚种群的序列库之间相似度较低，第勒尼安海的比西西里海峡的更加多样化和复杂。声学参数在研究区域之间也表现出变异性。仅在第勒尼安海检测到构成 Bray-call 序列的主要声学元素的不同变体。马尔可夫链模型表明，声学元素之间的转移概率并不均匀，特定的元素组合出现的概率更高。这些关于宽吻海豚 Bray-call 序列的新发现突出了这些发声的结构复杂性，并建议在未来研究中关注发声的背景以及这种声学排列可能的功能。
