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Phylogenetic review of tonal sound production in whales in relation to sociality

BACKGROUND: It is widely held that in toothed whales, high frequency tonal sounds called 'whistles' evolved in association with 'sociality' because in delphinids they are used in a social context. Recently, whistles were hypothesized to be an evolutionary innovation of social dol...

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Autores principales: May-Collado, Laura J, Agnarsson, Ingi, Wartzok, Douglas
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2000896/
https://www.ncbi.nlm.nih.gov/pubmed/17692128
http://dx.doi.org/10.1186/1471-2148-7-136
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author May-Collado, Laura J
Agnarsson, Ingi
Wartzok, Douglas
author_facet May-Collado, Laura J
Agnarsson, Ingi
Wartzok, Douglas
author_sort May-Collado, Laura J
collection PubMed
description BACKGROUND: It is widely held that in toothed whales, high frequency tonal sounds called 'whistles' evolved in association with 'sociality' because in delphinids they are used in a social context. Recently, whistles were hypothesized to be an evolutionary innovation of social dolphins (the 'dolphin hypothesis'). However, both 'whistles' and 'sociality' are broad concepts each representing a conglomerate of characters. Many non-delphinids, whether solitary or social, produce tonal sounds that share most of the acoustic characteristics of delphinid whistles. Furthermore, hypotheses of character correlation are best tested in a phylogenetic context, which has hitherto not been done. Here we summarize data from over 300 studies on cetacean tonal sounds and social structure and phylogenetically test existing hypotheses on their co-evolution. RESULTS: Whistles are 'complex' tonal sounds of toothed whales that demark a more inclusive clade than the social dolphins. Whistles are also used by some riverine species that live in simple societies, and have been lost twice within the social delphinoids, all observations that are inconsistent with the dolphin hypothesis as stated. However, cetacean tonal sounds and sociality are intertwined: (1) increased tonal sound modulation significantly correlates with group size and social structure; (2) changes in tonal sound complexity are significantly concentrated on social branches. Also, duration and minimum frequency correlate as do group size and mean minimum frequency. CONCLUSION: Studying the evolutionary correlation of broad concepts, rather than that of their component characters, is fraught with difficulty, while limits of available data restrict the detail in which component character correlations can be analyzed in this case. Our results support the hypothesis that sociality influences the evolution of tonal sound complexity. The level of social and whistle complexity are correlated, suggesting that complex tonal sounds play an important role in social communication. Minimum frequency is higher in species with large groups, and correlates negatively with duration, which may reflect the increased distances over which non-social species communicate. Our findings are generally stable across a range of alternative phylogenies. Our study points to key species where future studies would be particularly valuable for enriching our understanding of the interplay of acoustic communication and sociality.
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spelling pubmed-20008962007-10-05 Phylogenetic review of tonal sound production in whales in relation to sociality May-Collado, Laura J Agnarsson, Ingi Wartzok, Douglas BMC Evol Biol Research Article BACKGROUND: It is widely held that in toothed whales, high frequency tonal sounds called 'whistles' evolved in association with 'sociality' because in delphinids they are used in a social context. Recently, whistles were hypothesized to be an evolutionary innovation of social dolphins (the 'dolphin hypothesis'). However, both 'whistles' and 'sociality' are broad concepts each representing a conglomerate of characters. Many non-delphinids, whether solitary or social, produce tonal sounds that share most of the acoustic characteristics of delphinid whistles. Furthermore, hypotheses of character correlation are best tested in a phylogenetic context, which has hitherto not been done. Here we summarize data from over 300 studies on cetacean tonal sounds and social structure and phylogenetically test existing hypotheses on their co-evolution. RESULTS: Whistles are 'complex' tonal sounds of toothed whales that demark a more inclusive clade than the social dolphins. Whistles are also used by some riverine species that live in simple societies, and have been lost twice within the social delphinoids, all observations that are inconsistent with the dolphin hypothesis as stated. However, cetacean tonal sounds and sociality are intertwined: (1) increased tonal sound modulation significantly correlates with group size and social structure; (2) changes in tonal sound complexity are significantly concentrated on social branches. Also, duration and minimum frequency correlate as do group size and mean minimum frequency. CONCLUSION: Studying the evolutionary correlation of broad concepts, rather than that of their component characters, is fraught with difficulty, while limits of available data restrict the detail in which component character correlations can be analyzed in this case. Our results support the hypothesis that sociality influences the evolution of tonal sound complexity. The level of social and whistle complexity are correlated, suggesting that complex tonal sounds play an important role in social communication. Minimum frequency is higher in species with large groups, and correlates negatively with duration, which may reflect the increased distances over which non-social species communicate. Our findings are generally stable across a range of alternative phylogenies. Our study points to key species where future studies would be particularly valuable for enriching our understanding of the interplay of acoustic communication and sociality. BioMed Central 2007-08-10 /pmc/articles/PMC2000896/ /pubmed/17692128 http://dx.doi.org/10.1186/1471-2148-7-136 Text en Copyright © 2007 May-Collado et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
May-Collado, Laura J
Agnarsson, Ingi
Wartzok, Douglas
Phylogenetic review of tonal sound production in whales in relation to sociality
title Phylogenetic review of tonal sound production in whales in relation to sociality
title_full Phylogenetic review of tonal sound production in whales in relation to sociality
title_fullStr Phylogenetic review of tonal sound production in whales in relation to sociality
title_full_unstemmed Phylogenetic review of tonal sound production in whales in relation to sociality
title_short Phylogenetic review of tonal sound production in whales in relation to sociality
title_sort phylogenetic review of tonal sound production in whales in relation to sociality
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2000896/
https://www.ncbi.nlm.nih.gov/pubmed/17692128
http://dx.doi.org/10.1186/1471-2148-7-136
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