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UID:858@i2m.univ-amu.fr
DTSTART;TZID=Europe/Paris:20150923T150000
DTEND;TZID=Europe/Paris:20150923T160000
DTSTAMP:20150908T130000Z
URL:https://www.i2m.univ-amu.fr/evenements/detecting-molecular-signatures-
 of-convergent-evolution-followed-by-estimating-diversification-rates-from-
 the-fossil-record/
SUMMARY: (...): Detecting molecular signatures of convergent evolution\, fo
 llowed by\, Estimating diversification rates from the fossil record
DESCRIPTION:: The talk is divided into two independent parts.The first focu
 ses on the detection of evolutionary traces of phenotypic convergence in g
 enetic sequences. We consider a complex trait which is shared by a subset 
 of species and not observed among others. In order to assess in what exten
 t the genetic sequences of the species support the convergent evolution of
  the trait\, we ask the question “How much positions have evolved indepe
 ndently to a same amino acid (or nucleotide\, i.e "letter" of sequences) f
 or the species bearing the trait?”. This question cannot be answered wit
 hout uncertainty since we don't have access to the past of the genetic seq
 uences (only the contemporary ones are available). We show how to compute 
 the expectation of this number for each position under a standard model of
  sequences evolution. (joint work with O. Chabrol and P. Pontarotti\, I2M)
 In the second part\, we are interested in how fast species born and die (i
 .e. diversify). Diversification rates are estimated from phylogenies (i.e.
  trees figuring the parenthood of species) which contains extant and (some
 times) fossil taxa. By  nature\, rate estimations depend heavily on the ti
 me data provided in phylogenies\, which are  divergence times and (when us
 ed) fossil ages. Among these temporal data\, fossil ages are by far the mo
 st precisely known (divergence times are inferences calibrated with fossil
 s). We present an original method to compute the likelihood of a phylogene
 tic tree with fossils in which the only known time information is the foss
 il ages.Testing our approach on simulated data shows that the maximum like
 lihood rate estimates from the phylogenetic tree shape and the fossil date
 s are almost as accurate as the ones obtained by taking into account all t
 he data\, including the divergence times. Moreover they are substantially 
 more accurate than the estimates obtained only from the exact divergence t
 imes (without taking into account the fossil record). We finally estimate 
 the diversification and fossilization rates from a paleontological dataset
  (eupelycosaurs tree). (joint work with Michel Laurin\, Museum d'Histoire 
 Naturelle de Paris)Webpage
CATEGORIES:Séminaire,Mathématiques-Évolution-Biologie
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DTSTART:20150329T030000
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