Individuals of a given population share more behavioural traits with each other than with members of other populations. For example, in humans, traditions are specific to regions or countries. These cultural relationships can tell us about the history of the populations, their origin and the amount of exchange between them. In birds, regional dialects have been described in many species. However, the mechanisms with which dialects form in populations is not fully understood because it is difficult to analyse experimentally. Translocated populations, with their known histories, offer an opportunity to study these mechanisms. From the study of bird vocalisations we can make inferences regarding population structure and relationships as well as their history, individual behavioural state, neuronal and physiological mechanisms or development of neuronal learning. Too achieve this, cross-disciplinary approaches are necessary, combining field work, bioacoustic methods, statistical tools such as machine learning, ecological knowledge and phylogenetic methods. Here, I will describe computational methods for the treatment and classification of bird vocalisations and will use them to depict the relationships between bird populations. First, I discretise the data in order to define the cultural traits. Then phylogenetic tree-building methods are used. Two approaches are possible, first to map these traits onto known phylogenies and, second, to directly build the phylogeny of these traits. I describe the application of these methods to test several hypothesis on bird songs evolution related to both their history and the mechanisms with which they evolve. Evidence for the presence of dialects in the Puget Sound white-crowned sparrow (Zonotrichia leucophrys pugetensis) is provided on the basis of the syllable content of the songs. The absence of vocal sexual dimorphism is reported in the Australasian gannet (or takapu, Morus serrator), a member of the Sulidae family for which extensive sexual dimorphism has been reported in other species. Subsequently, convergence between the begging calls of several cuckoo species and their respective hosts is suggested by various bioacoustic methods. In addition, the male calls of the hihi (or stitchbird, Notiomystis cincta) is analysed in an island population. The corresponding pattern of variation suggests a post-dispersal acquisition of calls via learning which is in agreement with the most related species in the revised phylogeny of the hihi. Finally, the mechanisms of song evolution are depicted in translocated populations of tieke (or saddleback, Philesturnus carunculatus rufusater), resulting in the development of island dialects.
| Identifer | oai:union.ndltd.org:ADTP/284427 |
| Date | January 2010 |
| Creators | Ranjard, Louis |
| Publisher | ResearchSpace@Auckland |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated., http://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm, Copyright: The author |
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