Geographic and species variation in bottlenose dolphin (Tursiops spp.) signature whistle types

Dolphin sounds;Bottlenose dolphin--Vocalization

Gridley, Teresa ; Janik, Vincent ; Janik, Vincent

University:University of St Andrews

Department:Biology (School of)

关键词: Dolphin sounds;    Bottlenose dolphin--Vocalization;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/1910/TeresaGridleyPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

Geographic variation in the whistle vocalisations of dolphins has previously been reported. However, moststudies have focused on the whole whistle repertoire, with little attempt to classify sounds into biologicallyrelevant categories. Common bottlenose dolphins (Tursiops truncatus) use individually distinctive signaturewhistles which are thought to help maintain contact between conspecifics at sea. These whistles may show adifferent kind of variation between populations than non-signature whistles. Here I investigate signaturewhistle use and variation in the two recognised species of bottlenose dolphins (T. truncatus and T. aduncus)from populations inhabiting the coastal waters of the North America, Scotland, South Africa, Tanzania,Japan, Australia and New Zealand, and one captive colony. I identified likely signature whistles (signaturewhistles types, SWTs) from acoustic recordings by combining two novel techniques: automated contourcategorisation in ARTwarp (Deecke and Janik, 2006) and a specific bout analysis based on the timing ofsignature whistle production in T. truncatus termed SIGID (Janik et al. in press). Three ways of categorisingthe contours were tested and between 87 and 111 SWTs were identified in total. Repeated emissions ofstereotyped contours were apparent in the repertoire of all T. aduncus populations using both automated andhuman observer categorisation, providing good evidence for signature whistle use in this species. There wassignificant inter-specific variation in the frequency parameters, looping patterns and duration of SWTs.Inflection points, duration and measures of SWT complexity showed high variation within populations,suggesting inter- and intra-individual modification of these parameters, perhaps to enhance identity encodingor convey motivational information. Using 328 bases of the mtDNA control region, I found high levels ofpopulation differentiation (FST and φST) within the genus Tursiops. These data do not support a link betweenmtDNA population differentiation and variability in call type. Instead, morphological variations at thespecies level, and learned differences at the population level, better explain the variation found.