Physical constraints of cultural evolution of dialects in killer whales

Filatova, Olga A.; Samarra, Filipa I. P.; Barrett‐Lennard, Lance G.; Miller, Patrick J. O.; Ford, John K. B.; Yurk, Harald; Matkin, Craig O.; Hoyt, Erich

doi:10.1121/1.4967369

Cited by 7 publications

(9 citation statements)

References 55 publications

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“…In space, if one of the components is not recognizable due to distance or masked by noise, the whales can still use the other component to identify the caller's family affiliation. In time, if in some families the contour shape of the higher-or lower-frequency component randomly converges through the process of cultural evolution [42], the other component still remains different between the families and allows listeners to discriminate between them.…”

Section: Discussionmentioning

confidence: 99%

“…Killer whale dialects slowly change in time through learning errors and innovations [ 2 , 25 , 49 – 51 ]; this process of cultural change is called cultural evolution [ 52 , 53 ]. Since the variability of sound contours is limited due to the natural physical constrains, call contours of unrelated killer whale social units can sometimes become more similar due to the random convergence [ 42 ]. This would impede the discrimination between these two pods on a distance, when some call features are masked.…”

Section: Discussionmentioning

confidence: 99%

“…When both call components are detectable, biphonation can still be useful to duplicate the recognition potential of stereotyped calls, because the shape of call contours can randomly converge in unrelated social units [42]. Killer whale calls are not inherited genetically, but are rather learned from mother and other maternal relatives.…”

Section: Plos Onementioning

confidence: 99%

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Independent acoustic variation of the higher- and lower-frequency components of biphonic calls can facilitate call recognition and social affiliation in killer whales

Filatova

2020

PLoS ONE

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Each resident-type (R-type) killer whale pod has a set of stereotyped calls that are culturally transmitted from mother to offspring. The functions of particular call types are not yet clearly understood, but it is believed that calls with two independently modulated frequency components (biphonic calls) play an important role in pod communication and cohesion at long ranges. In this study we examined the possible functions of biphonic calls in R-type killer whales. First, we tested the hypothesis that the additional component enhances the potential of a call to identify the family affiliation. We found that the similarity patterns of the lowerand higher frequency components across the families were largely unrelated. Calls were classified more accurately to their respective family when both lower-and higher-frequency components were considered. Second, we tested the long-range detectability of the lowerand higher-frequency components. After adjusting the received levels by the killer whale hearing sensitivity to different frequency ranges, the sensation level of the higher-frequency component was higher than the amplitude of the lower-frequency component. Our results suggest that the higher-frequency component of killer whale biphonic calls varies independently of the lower-frequency component, which enhances the efficiency of these calls as family markers. The acoustic variation of the higher-frequency component allows the recognition of family identity of a caller even if the shape of the lower-frequency component accidentally becomes similar in unrelated families. The higher-frequency component can also facilitate family recognition when the lower-frequency component is masked by low-frequency noise.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Independent acoustic variation of the higher- and lower-frequency components of biphonic calls can facilitate call recognition and social affiliation in killer whales

Filatova

2020

PLoS ONE

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“…Norwegian, Icelandic and Southern Resident populations were not classified in any consistent pattern. Killer whale calls change in time, but their structural variation is limited by the physical and/or cultural constrains (Filatova et al, 2016). Therefore, diverging populations reach the maximum repertoire divergence, and after that their similarity can no longer decrease, but instead it can increase due to random convergences.…”

Section: Discussionmentioning

confidence: 99%

Crowd intelligence can discern between repertoires of killer whale ecotypes

et al. 2018

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Call classifications by human observers are often subjective yet they are critical to studies of animal communication, because only the categories that are relevant for the animals themselves actually make sense in terms of correlation to the context. In this paper we test whether independent observers can correctly detect differences and similarities in killer whale repertoires. We used repertoires with different a priori levels of similarity: from different ecotypes, from different oceans, from different populations within the same ocean, and from different local subpopulations of the same population. Calls from nine killer whale populations/subpopulations were pooled into a joint sample set, and eight independent observers were asked to classify the calls into separate categories. None of the observers' classifications strongly followed the known phylogeny of the analyzed repertoires. However, some phylogenetic relationships were reflected in the classifications substantially better than others. Most observers correctly separated the calls from two North Pacific ecotypes. Call classifications averaged across multiple observers reflected the known repertoire phylogenies better than individual classifications, and revealed the similarity of repertoires at the level of subpopulations within the same population, or closely related populations.

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“…2 e, Miller 2002 ). Sounds based on a non-pulsed tonal format with a narrow-band tone above 4 kHz were categorised as whistles (Filatova et al 2016 ), visually and aurally distinguishable from pulsed calls (Ford 1989 ; Riesch et al 2006 ), with an approximately maximum frequency range 3–17 kHz (Fig. 2 f, Thomsen et al 2001 ), and those with fundamental frequency contours above 17 kHz, were classified as high-frequency whistles (Fig.…”

Section: Methodsmentioning

confidence: 99%

Icelandic herring-eating killer whales feed at night

et al. 2017

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Herring-eating killer whales debilitate herring with underwater tail slaps and likely herd herring into tighter schools using a feeding-specific low-frequency pulsed call (‘herding’ call). Feeding on herring may be dependent upon daylight, as the whales use their white underside to help herd herring; however, feeding at night has not been investigated. The production of feeding-specific sounds provides an opportunity to use passive acoustic monitoring to investigate feeding behaviour at different times of day. We compared the acoustic behaviour of killer whales between day and night, using an autonomous recorder deployed in Iceland during winter. Based upon acoustic detection of underwater tail slaps used to feed upon herring we found that killer whales fed both at night and day: they spent 50% of their time at night and 73% of daytime feeding. Interestingly, there was a significant diel variation in acoustic behaviour. Herding calls were significantly associated with underwater tail slap rate and were recorded significantly more often at night, suggesting that in low-light conditions killer whales rely more on acoustics to herd herring. Communicative sounds were also related to underwater tail slap rate and produced at different rates during day and night. The capability to adapt feeding behaviour to different light conditions may be particularly relevant for predator species occurring in high latitudes during winter, when light availability is limited.Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-016-3059-8) contains supplementary material, which is available to authorized users.

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Physical constraints of cultural evolution of dialects in killer whales

Cited by 7 publications

References 55 publications

Independent acoustic variation of the higher- and lower-frequency components of biphonic calls can facilitate call recognition and social affiliation in killer whales

Independent acoustic variation of the higher- and lower-frequency components of biphonic calls can facilitate call recognition and social affiliation in killer whales

Crowd intelligence can discern between repertoires of killer whale ecotypes

Icelandic herring-eating killer whales feed at night

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