CLOE SUMMER SYMPOSIUM-Telling the time on the tree of life

Date: Thursday 6th June

Time: 3pm prompt start

Location: Gavin de Beer Lecture Theatre, Anatomy Building

Prof. Rachel Warnock, Friedrich-Alexander-Universität Erlangen-Nürnberg

"Demystifying the tripartite model for Bayesian divergence time estimation"

Placing speciation or lineage divergence events in the context of geological time is fundamental to our understanding of macroevolution. Phylogenetic dating allows us to leverage information from the fossil and molecular records simultaneously, but is not without challenges. The tripartite model used for Bayesian divergence time estimation can be readily separated into its component models: the substitution model, the clock model and the tree model. I will provide an introduction to this framework, as well as highlighting some of the advantages and caveats to applying the model in practice.

Dr Mario dos Reis, Queen Mary University of London

"Reconciling fossils and molecules to reconstruct the timeline of mammal evolution"

Application of early molecular-clock dating methodologies to date the origin of mammal groups resulted in ancient estimates for the origin of many groups, implying large gaps in their corresponding fossil records and generating great controversy. In this talk, I will discuss the application of state-of-the-art Bayesian molecular-clock methodologies to the newest genome sequence datasets, which have resulted in reconciliation of molecular and fossil ages. However, the age of the last common ancestor of mammals with a placenta still remains contentious.

Prof Graham Budd, University of Uppsala

"Can we tell the time with the fossil record?"

Although the fossil record is widely considered to contain important information about the timings of evolutionary events, it is also commonly contradicted, sometimes grossly, by the results of molecular clocks. While the dates from clocks and rocks have often crept closer to each other in recent years, any residual gaps are still largely explained by recourse to the inadequacy of the fossils. Here, I will argue that this creates problems about testability and falsifiability, and that the fossil record at least sometimes provides powerful evidence for dating the origin of a clade. In these cases, it (should) act as a standard against which the arguably still untested mechanisms of the molecular clock can be tested and refined: in the end, the fossil record and molecular clock, both properly considered, cannot disagree.