ИСТИНА

Killer whale is among the few species in which cultural change accumulates over many generations, leading to the cumulative cultural evolution. Killer whales have group-specific vocal repertoires of stereotyped calls with complex structure, which are thought to be learned rather than being genetically coded. It is supposed that divergence between vocal repertoires of sister pods increase gradually over time due to random learning mistakes and innovations. In this case, the similarity of calls must be correlated with pod relatedness and, consequently, with each other. In this study we tested this prediction by comparing the patterns of call similarity between different matrilines of resident killer whales from Eastern Kamchatka. We calculated the similarity of seven components from three call types across 14 matrilines. In contrast with the theoretical predictions, units formed different clusters on the dendrograms made by different calls and even by different components of the same call. Similarity patters were significantly correlated only in two of 21 possible pair-wise comparisons of distance matrices. We suggest three possible explanations of this phenomena. First, it is possible that different call components change in time with different speed and/or in different directions. Second, horizontal cultural transmission of call features may occur between matrilines. Third, the lack of agreement between similarity patterns of different components may be the result of some constraints of call structure. In future studies we suggest to check if the similarity patterns of different call features are correlated to prevent errors in estimates of similarity of stereotyped calls.