| Summary: | Studies of animal culture have normally not included a consideration of cetaceans. However, cultural transmission may be a significant source of variation in the behaviour of whales and dolphins, especially as regards their vocal signals. There is good evidence for cultural transmission in several cetacean species. There have been suggestions of gene-culture co-evolution in cetaceans, and culture may be implicated in some unusual behavioural and life history traits of the whales and dolphins. One such species is the sperm whale (Physeter mactocephalus). I studied variation in the vocal output of 'codas', short repeated patterns of clicks, recorded from sperm whale social groups. I evaluated five methods of comparing repertoires of 'codas' and concluded that using multiple techniques concurrently allows the drawing of relatively robust conclusions about repertoire similarity. Using these methods, I showed that the coda repertoires of all 18 known social units, and 61 of 64 groups (about two social units in temporary association) that were recorded in the South Pacific and Caribbean between 1985 and 2000 can be reliably allocated into six acoustic 'clans', five in the Pacific and one in the Caribbean. Clans have ranges that span thousands of kilometres, are sympatric, contain many thousands of whales, and most likely result from cultural transmission of vocal patterns. Culture may thus be a more important determinant of sperm whale population structure than genes or geography; this has major implications for our understanding of the species' behavioural and population biology. I used the multi-pulse structure of sperm whale clicks to estimate the size of animals producing codas in recordings of a single social unit. These data showed that more than one animal was producing codas and that several coda types were shared. Thus the codas recorded from these animals represent a shared repertoire, with coda production not limited to a single animal and coda types shared between individuals within the unit. I attempted to test for differential response to the playback of clan and non-clan codas to sperm whale social groups off Chile, but found little evidence for such a response. (Abstract shortened by UMI.) Thesis (Ph.D.)--Dalhousie University (Canada), 2003.
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