Empirical phylogenies are typically much more imbalanced that what is expected from homogeneous speciation models. While the hypothesis of common diversification rates along lineages makes sense when the studied clade is small enough, it more difficult to believe for large groups within which species are likely to have very different life history traits and evolutionary histories. Previous phylogenetic approaches for detecting changes in diversification rates across a phylogenetic tree have focused on ‘major’ rate shifts, with the underlying idea that few rare events, such as key innovations, facilitate the invasion of new adaptive zones, a drastic impact on diversification rates. Another view of evolution is that speciation and extinction rates may vary gradually across lineages as a response to the particular biotic and abiotic environment experienced by each lineage. Such changes in diversification rates likely occur far more frequently than key innovations, resulting in heterogeneous diversification rates at much finer taxonomic scales. I will present a new Bayesian approach for estimating lineage specific diversification rates. Our approach is based on a birth-death diversification process where diversification rates are inherited at speciation, but with a shift. We test it on a large simulated dataset of simulated phylogenies to assess its statistical performances, and show that it is able to accurately infer both the way shift happen at speciation events – how constrained they are by their parental value, and whether there is a trend in rates evolution – and the lineage specific diversification rates. The latter is a critical step to our understanding of the processes that lead some species groups to diversify faster than others. We then apply our method to time-calibrated phylogenies for 42 birds clades. This analysis reveals a pervasive pattern of declines in speciation rates over time congruent with previous studies, together with a remarkable heterogeneity in speciation rates. We show that the variability is comparable within and between clades, suggesting that rate variation may be much more gradual than currently thought and implemented in existing models. Our results emphasize the need to consider diversification models that embrace the pervasive heterogeneity of the evolutionary process.
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Lucas Escobar, doctorant en philosophie des sciences historiques à l'ENS
RdV à 12h30, dans le grand amphithéâtre d'entomologie, 45 rue Buffon, Paris. - ImageLes Séminaires de l'ISYEB accueillent
Pierre Galipot, ISYEB.
Mardi 5 mars 2024 à 12h30 dans le grand amphithéâtre d'entomologie, 45 rue Buffon, Paris. - ImageLes Séminaires de l'ISYEB accueillent
Gavin Naylor (full professor à l’Université de Floride et directeur du Florida Program for Shark Research)
Mardi 12 décembre 2023 16h - petit amphithéâtre d'entomologie, 45 rue Buffon, Paris. - ImageLes Séminaires de l'ISYEB accueillent
Oscar Gaggiotti (School of Biology, University of St Andrews)
Jeudi 7 décembre 2023 à 14h. dans la Salle de géologie au 43 rue Buffon. Paris