Mammalian phylogeny reveals recent diversi cation rate shifts
Seminar Room 1, Newton Institute
AbstractPhylogenetic trees of present-day species allow investigation of the rate of evolution which led to the present-day diversity. A recent analysis of the complete mammalian phylogeny challenged the view of explosive mammalian evolution after the K/T boundary (65 Ma). However, due to lack of appropriate methods, the diversication rates in the more recent past of mammalian evolution could not be determined. Here, I provide a method which reveals that the tempo of mammalian evolution did not change until about 33 Ma. This constant period was followed by a peak of diversication rates between 33 and 30 Ma. Thereafter, diversication rates remained high and constant until 8.55 Ma. Diversication rates declined signicantly at 8.55 and 3.35 Ma. Investigation of mammalian subgroups (marsupials, placentals, and the six largest placental subgroups) reveals that the diversication rate peak at 33-30 Ma ago is mainly driven by rodents, cetartiodactyla and marsupials. The recent diversication rate decrease is signicant for all analyzed subgroups but eulipotyphla, cetartiodactyla and primates. My likelihood approach is not limited to mammalian evolution. It provides a robust framework to infer diversication rate changes and mass extinction events in phylogenies, reconstructed from e.g. present-day species or virus data. In particular, the method is very robust towards noise and uncertainty in the phylogeny, and can account for incomplete taxon sampling.
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