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Article overview
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Detection of adaptive shifts on phylogenies using shifted stochastic processes on a tree | Paul Bastide
; Mahendra Mariadassou
; Stéphane Robin
; | Date: |
2 Aug 2015 | Abstract: | Comparative and evolutive ecologists are interested in the distribution of
quantitative traits among related species. The classical framework for these
distributions consists of a random process running along the branches of a
phylogenetic tree relating the species. We consider shifts in the process
parameters, which reveal fast adaptation to changes of ecological niches. We
show that models with shifts are not identifiable in general. Constraining the
models to be parsimonious in the number of shifts partially alleviates the
problem but several evolutionary scenarios can still provide the same joint
distribution for the extant species. We provide a recursive algorithm to
enumerate all the equivalent scenarios and to count the effectively different
scenarios. We introduce an incomplete-data framework and develop a maximum
likelihood estimation procedure based on the EM algorithm. Finally, we propose
a model selection procedure, based on the cardinal of effective scenarios, to
estimate the number of shifts and prove an oracle inequality. | Source: | arXiv, 1508.0225 | Services: | Forum | Review | PDF | Favorites |
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