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Field of Study - Evolutionary Biology
Supervisor: Dr David Paull (PEMS)
Co-Supervisor: Dr Steve Cooper (South Australian Museum), Prof Roger Butlin (University of Sheffield, UK)
Research Topic - Systematics, phylogeography, and speciation of the morabine grasshopper (genus Vandiemenella) in south-eastern Australia
Australian Digital Theses Program:
http://www.lib.adfa.edu.au/adt/adt_browse.htm - Kawakami
UNSW @ ADFA Postgraduate Opportunity
Between 15-20 September 2005 I attended the tenth congress of the European Society for Evolutionary Biology (ESEB) in Poland to present my PhD research and discuss future research plans with my co-supervisor, Prof. Roger K. Butlin (University of Sheffield , UK).
The ESEB congress was one of the most successful and attractive international meetings in the field of evolutionary biology in 2005. It was composed of five plenary lectures, and 29 symposia with many oral and poster presentations. In particular, the symposium, “Hybrid zones and speciation”, gave me valuable insights and suggestions for my PhD research in speciation, phylogeography and systematics of chromosomally diverse Australian morabine grasshoppers. Europe has a longstanding tradition in hybrid zone and speciation research, including studies of the meadow grasshopper ( Chorthippus parallelus ), fire-bellied toad ( Bombina bombina/variegata ), and house mouse ( Mus musculus/domesticus ). Therefore, presentations of these “icon” researches significantly improved my knowledge in this field. In addition, there are many theoretical biologists in Europe whose focus is to understand speciation processes and mechanisms using hybrid zone systems. Prof. Nick Barton ( University of Edinburgh ), a world-leading theoretical biologist in hybrid zone research, gave a particularly educative lecture, which will help immensely with my PhD thesis literature review.
My poster presentation attracted a great deal of attention, so it was an excellent opportunity to exchange knowledge and information that will be invaluable in the development of my research project. Importantly, Dr Graham Wallis (University of Otago) gave me many constructive suggestions. He pointed out that my sampling was currently too biased towards hybrid zones on Kangaroo Island for an optimal phylogeographic analysis. This bias was inevitable at that time because the primary focus of my research in this region has been hybrid zone analyses, so available resources will need to be allocated efficiently for the remainder of my field work. Now, additional samples are currently being analysed to eliminate sampling bias and investigate fine-scale phylogeography.
It was very good timing to meet with my co-supervisor, Prof. Roger Butlin , so that we could discuss the results to date and further develop my project. He affirmed my approach to investigate hybrid zone gene flow and phylogeography using microsatellite markers and nuclear/mitochondrial DNA sequencing. I now need to further extend this approach to develop a comprehensive picture of the evolutionary history of the morabine grasshopper. He also pointed out that it is important to fill in some sampling gaps near a hybrid zone on Kangaroo Island , where grasshopper samples were not successfully collected on the last field trip due to unexpected weather conditions. Because some genetic markers considerably introgress across the hybrid zone, I will not be able to estimate accurate hybrid zone width and centre without those unsampled populations. Based on this meeting, it has now been agreed that I will conduct a field trip in September to obtain samples from these populations.
In sum, the trip was very fruitful. I obtained many useful suggestions through discussions and presented new information from my research into about hybrid zones in Australia . Finally, I would like to thank both the School of PEMS and Postgraduate Research Student Travel Grants offered by the Business Services Office for providing financial support.
Summary of Work
Since the publication of Charles Darwin's "The Origin of Species" in 1859, the processes of evolution and speciation have been principal but little-understood subjects in biology. The ultimate goal of my research is to understand the processes of genetic evolution and speciation using the Australian morabine grasshopper, Vandiemenella viatica.
Vandiemenella viatica provides an excellent opportunity to explore evolutionary genetics and speciation because of their chromosomal diversity and unique geographic distribution. V. viatica is composed of at least 12 chromosomally divergent races, which are distributed without apparent overlapping and form narrow hybrid zones where different races meet and hybridize. Theoretical studies have suggested that hybrid zones are maintained by a balance between selection against hybrids and their gene flow. In addition, it is suggested that chromosomal rearrangements may change recombination patterns and hence modify patterns of gene flow. However, these hypotheses have not been experimentally tested in the V. viatica species group.
Using allozyme, mitochondrial and nuclear DNA markers, I aim to elucidate the population genetic architecture and phylogeography of the V. viatica species group in south-eastern Australia in order to evaluate the roles of chromosomal rearrangements in the process of speciation. Understanding of roles of chromosomal rearrangements and genetic configuration of hybrid zones will shed light on species isolation mechanisms and the genetic basis of biodiversity in this group.