Invited Speaker: Ting Chau-Ti

Speaker Introduction:

1. 2006 Aug.-present          Associate Professor, Department of Life Science, Institute of Ecology and Evolutionary Biology & Institute of Zoology, National Taiwan University
2. 2010 July.-2011 July.       Visiting Professor, Department of Ecology and Evolution, University of Chicago
3. 2004 Aug.-2006 July.    Associate Professor, Institute of Molecular and Cellular Biology, National Tsing Hua University
4. 2005 Feb.-2005 Aug.     Visiting Scholar, Section of Evolution and Ecology, University of California, Davis
5. 2000 Aug.-2004 July.    Assistant Professor, Department of Life Science, National Tsing Hua University
6. 1997 June.-2000 July.    Research associate, Department of Ecology and Evolution, The University of Chicago

Abstract:

Fatty acid desaturases play important roles in the lipid metabolism and the biosynthesis of pheromones in insects. Our previous work in Drosophila showed that functional divergence driven by positive selection in the desaturase genes are responsible for the sex pheromonal diversity contributing to species recognition. We also found that recurrent duplication events of a desaturase gene, desatF, took place in several Drosophila lineages. This multiple duplication of desatF further contributes to the pheromonal diene complexity in several species. While gene duplication events are relatively frequent, gene degeneration is not scarce. These degenerated copies provide a good model to understand the pseudogenization process. Among nine members of D. melanogaster species subgroup, six show no desatF gene expression with various levels of degeneration in the coding region. The fact that no shared degenerated alleles were observed in our population samples suggests that these pseudogenization events might occur independently. In addition, high indel and nucleotide  polymorphisms have been accumulated in both D. mauritiana and D. yakuba lineages whereas the reduction of polymorphism was found in their sibling species. Based on population genetics analyses, this reduction in multiple species might result from a recent selective sweep. This further implies that pseudogenes like desatF could evolve non-neutrally and at very different rates between sibling species. In conclusion, the rapid independent turnover of desaturase genes is one of the driving forces in pheromonal diversity and speciation.