Gero Shane, Whitehead Hal, Rendell Luke
Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Jutland, Denmark; Department of Biology, Dalhousie University, Halifax, Canada B3H 4J1; Centre for Social Learning and Cognitive Evolution, and Sea Mammal Research Unit, School of Biology, University of St Andrews, St Andrews KY16 9TH, UK.
Department of Biology , Dalhousie University , Halifax, Canada B3H 4J1.
R Soc Open Sci. 2016 Jan 20;3(1):150372. doi: 10.1098/rsos.150372. eCollection 2016 Jan.
The 'social complexity hypothesis' suggests that complex social structure is a driver of diversity in animal communication systems. Sperm whales have a hierarchically structured society in which the largest affiliative structures, the vocal clans, are marked on ocean-basin scales by culturally transmitted dialects of acoustic signals known as 'codas'. We examined variation in coda repertoires among both individual whales and social units-the basic element of sperm whale society-using data from nine Caribbean social units across six years. Codas were assigned to individuals using photo-identification and acoustic size measurement, and we calculated similarity between repertoires using both continuous and categorical methods. We identified 21 coda types. Two of those ('1+1+3' and '5R1') made up 65% of the codas recorded, were shared across all units and have dominated repertoires in this population for at least 30 years. Individuals appear to differ in the way they produce '5R1' but not '1+1+3' coda. Units use distinct 4-click coda types which contribute to making unit repertoires distinctive. Our results support the social complexity hypothesis in a marine species as different patterns of variation between coda types suggest divergent functions, perhaps representing selection for identity signals at several levels of social structure.
“社会复杂性假说”认为，复杂的社会结构是动物通讯系统多样性的驱动因素。抹香鲸拥有层次分明的社会结构，其中最大的亲和结构——声学氏族，在大洋盆地尺度上由被称为“尾声”的声学信号的文化传播方言标记。我们利用来自六个年份的九个加勒比海社会单位的数据，研究了个体鲸鱼和社会单位（抹香鲸社会的基本元素）之间尾声 repertoire 的差异。通过照片识别和声学尺寸测量将尾声分配给个体，我们使用连续和分类方法计算 repertoire 之间的相似度。我们识别出21种尾声类型。其中两种（“1+1+3”和“5R1”）占记录的尾声的65%，在所有单位中都有共享，并且在该种群的 repertoire 中占据主导地位至少30年。个体在发出“5R1”尾声的方式上似乎存在差异，但发出“1+1+3”尾声的方式没有差异。各单位使用不同的四咔嗒尾声类型，这使得单位 repertoire 具有独特性。我们的结果支持了一种海洋物种中的社会复杂性假说，因为尾声类型之间不同的变异模式表明了不同的功能，可能代表了在社会结构的几个层面上对身份信号的选择。
