tailieunhanh - Báo cáo y học: "Topological variation in single-gene phylogenetic trees"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Topological variation in single-gene phylogenetic trees. | Minireview Topological variation in single-gene phylogenetic trees Jose Castresana Address Department of Physiology and Molecular Biodiversity Institute of Molecular Biology of Barcelona CSIC 08034 Barcelona Spain. Email jcvagr@ Published 13 June 2007 Genome Biology 2007 8 216 doi gb-2007-8-6-2l6 The electronic version of this article is the complete one and can be found online at http 2007 8 6 216 2007 BioMed Central Ltd Abstract A recent large-scale phylogenomic study has shown the great degree of topological variation that can be found among eukaryotic phylogenetic trees constructed from single genes highlighting the problems that can be associated with gene sampling in phylogenetic studies. In 1982 Penny Foulds and Hendy 1 made a test of the theory of evolution by comparing phylogenetic trees constructed from different protein-coding genes from the same set of species. Specifically they tested whether a unique evolutionary tree relating these genes existed or not and whether it could be recovered. The existence of such a tree was important not only to confirm the theory of evolution but also to show that this theory allowed quantitative and falsifiable predictions. At that time five proteins from 11 mammalian species were available for the study but each protein produced different trees. At first sight this contradicted the existence of a unique tree. However the authors being aware of the methodological difficulties in phlyogenetic reconstruction did not expect the five trees to be identical. Rather they expected them to be similar. To measure topological dissimilarity between trees they made use of the symmetric difference distance also know as the Robinson-Foulds distance which had just been introduced 2 and found that the trees obtained from the five genes were indeed more similar than expected by chance proving the existence of a unique tree relating these sequences. This was a simple but powerful study that opened the