Molecular Dating and Divergence Time Estimation

Molecular dating and divergence time estimation encompass a suite of analytical frameworks designed to reconstruct the temporal dimension of evolutionary history by translating genetic differences into chronological intervals. Central to these efforts is the molecular clock concept, which posits that nucleotide or amino acid substitutions accumulate at measurable rates. Early approaches assumed a strict clock—constant rate across all lineages—while modern methods employ relaxed clocks to accommodate rate heterogeneity among taxa. Calibrations derived from fossil records, geological events or dated biogeographical scenarios anchor nodes in phylogenetic trees, generating chronograms with branches scaled to time. Bayesian and maximum‐likelihood approaches jointly estimate tree topology, substitution rates and divergence times, quantifying uncertainty in age estimates. Advances in computational power, the proliferation of phylogenomic data sets and innovations in statistical modelling have expanded the scope of molecular dating, enabling resolution of deep divergences across the Tree of Life, assessment of rapid radiations and integration of horizontal gene transfer constraints. These methods underpin studies of co‐evolution, biogeographical dispersal and macroevolutionary dynamics, offering a temporal framework that unifies genetics, palaeontology and earth sciences.

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Recent methodological innovations have addressed the challenge of incorporating relative time constraints, such as those inferred from horizontal gene transfers, into chronogram estimation by minimally adjusting Bayesian‐sampled trees to satisfy both absolute and relative node constraints, yielding more internally consistent time trees. Concurrently, new autocorrelated, Bayesian shrinkage models leverage heavy‐tailed priors and efficient Hamiltonian Monte Carlo sampling to infer heritable clock rate variation across large phylogenies, markedly improving scalability and the detection of lineage‐specific rate shifts without prior knowledge of clock placement. Foundational work on relaxed phylogenetic analysis has established a continuum of clocklikeness between strict molecular clocks and unrooted models by introducing intermediate relaxed‐clock models that jointly estimate branch‐specific rates and divergence times in the face of calibration and rate uncertainty, providing a means to evaluate clocklike behaviour across genes and enabling precise placement of major evolutionary splits.

Molecular Dating and Divergence Time Estimation publication trend

The graph below shows the total number of articles in molecular dating and divergence time estimation across all publications each year (not limited to Nature Index journals).

Technical terms

Molecular clock: A model that relates genetic substitution rates to absolute time, used to estimate when divergences occurred.

Relaxed clock: An extension of the strict molecular clock allowing substitution rates to vary among lineages according to specified statistical distributions.

Chronogram: A phylogenetic tree with branch lengths scaled to represent time rather than genetic change.

Calibration: An external temporal constraint, often derived from fossils, geological events or biogeographical data, used to anchor nodes in a chronogram.

Bayesian inference: A statistical framework that integrates prior information and observed data to estimate posterior distributions of model parameters, including divergence times and substitution rates.

References

1. DaTeR: error-correcting phylogenetic chronograms using relative time constraints. Bioinformatics (2023).
2. Shrinkage-based Random Local Clocks with Scalable Inference. Molecular Biology and Evolution (2023).
3. A General Comparison of Relaxed Molecular Clock Models. Molecular Biology and Evolution (2007).