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SUMMARY: Building and fitting a stochastic phylogentic model for Dollo tra
 its\, and its application to reconstructing the diversification of the Ind
 o-European languages - Geoff Nicholls\, Oxford
DTSTART:20090116T160000Z
DTEND:20090116T170000Z
UID:TALK16632@talks.cam.ac.uk
CONTACT:8047
DESCRIPTION:Abstract: Binary trait data record the presence or absence of\
 ndistinguishing traits in individuals. We treat the problem of\nestimating
  ancestral trees with time depth from binary trait data.\nEach homology cl
 ass of traits has a unique birth event on the tree\,\nand the birth event 
 of a trait that is visible at the leaves is biased\ntowards the leaves. Tr
 aits observed at just one leaf are usually\ndiscarded from the data. We mo
 del the evolution of sets of traits as a\nbirth-death process for set elem
 ents. We integrate many dimensions of\nthe missing data using a Felsenstei
 n-style pruning recursion\, and\nanalyse the resulting posterior distribut
 ion on trees. We illustrate\nBayesian inference for a binary-trait data-se
 t measured on 24 ancient\nand modern Indo-European languages\, extending t
 he model to include\nrate heterogeneity in the evolution via point-like ca
 tastrophe events.\nThe root age and tree topology are of particular intere
 st to the\nscientists who gathered these data. In our prior on trees\, the
 \nmarginal prior distribution of the root time is uniform. We present an\n
 analysis of the robustness of our results to model misspecification\,\nthr
 ough analysis of predictive distributions for external data\, and\nsimulat
 ion studies. Part of the work I am presenting is joint with\nRussell Gray 
 of the University of Auckland\, and part is joint with\nRobin Ryder\, of O
 xford University.\n
LOCATION:MR12\, CMS\, Wilberforce Road\, Cambridge\, CB3 0WB
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