Meeting Abstract

1.3  Tuesday, Jan. 4  Signal, Noise, and Molecular Divergence Time Estimates DORNBURG, A*; TOWNSEND, J; SARGIS, E; NEAR, TJ; Yale University; Yale University; Yale University; Yale University alex.dornburg@yale.edu

Instances of discordance between molecular age estimates or between molecular age estimates and the fossil record have been reported across the Tree of Life. As most molecular divergence time methods rely on the successful integration of neontological and paleontological data, a variety of variables could potentially underlie cases of discordant age inferences such as calibration choice, calibration placement, substitution model selection, or the type of molecular clock method utilized. However, objectively evaluating the utility of the individual gene sequences to be used for an analysis is an area that has received much less attention. The phenomenon of nucleotide saturation, or repeated convergence of replicate character states in an alignment, has the potential to bias phylogenetic inferences of topology as well as mislead divergence time estimation. Using a phylogenetic informativeness framework, we explore how phylogenetic signal and noise over specified time intervals affect the credibility of discordant age estimates between nuclear and mitochondrial sequence data for three taxonomic groups spanning different time intervals: primates, fishes, and whales. Our results demonstrate that the utility of different gene sequences for the same phylogenetic problem is heterogenous, and that the credibility of conflicting age and topological estimates can be directly addressed by phylogenetic informativeness theory.