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Relaxed phylogenies and dating with confidence aspnetdating

Recent work has shown that pollen of the myrtle family, Myrtaceae, can be classified into a number of morphological groups that are synapomorphic with molecular groups.

By assembling a data matrix of pollen morphological characters from extant and fossil Myrtaceae, we were able to measure the fit of 26 pollen fossils to a molecular phylogenetic tree using parsimony optimisation of characters.

Enfin, plusieurs développements prometteurs pour l’avenir de la discipline sont soulignés, en particulier dans le cadre de l’amélioration du processus de calibration.

The identification and application of reliable fossil calibrations represents a key component of many molecular studies of evolutionary timescales.

► Twenty-six fossil pollen parsimoniously tested to select those appropriate as calibrations.

► Eight fossil pollen selected as age calibrations in a Bayesian phylogenetic analysis.

► Fossil pollen is a robust calibration approach for relaxed molecular-clock dating.Molecular dating has now become a common tool for many biologists and considerable methodological improvements have been made over the last few years.However, the practice of estimating divergence times using molecular data is highly variable among researchers and it is not straightforward for a newcomer to the field to know how to start.In studies of plants, most paleontological calibrations are associated with macrofossils.However, the pollen record can also inform age calibrations if fossils matching extant pollen groups are found.I then provide some guidelines for the interpretation of results and briefly review some alternatives to molecular dating for obtaining divergence times.Last, I present some promising developments for the future of the field, related to the improvement of the calibration process.La datation moléculaire est devenue un outil commun pour de nombreux biologistes et des progrès méthodologiques considérables ont été apportés ces dernières années.Cependant, l’estimation des temps de divergence à partir de données moléculaires demeure très variable dans sa pratique et sa mise en œuvre est délicate pour le novice.We find no significant rate autocorrelation among branches in three large datasets, suggesting that autocorrelated models are not necessarily suitable for these data.In addition, we place these datasets on the continuum of clocklikeness between a strict molecular clock and the alternative unrooted extreme.


  1. We describe how it can be used to estimate phylogenies and divergence. 2006 Relaxed Phylogenetics and Dating with Confidence. Relaxed-clock models.

  2. Molecular dating has now become a common tool for many biologists and considerable methodological improvements have been made over the last few years.

  3. Unlike earlier molecular clock analyses, Bayesian Markov chain Monte Carlo MCMC and maximum likelihood ML techniques can incorporate rate

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