Molecular and morphological clocks for estimating evolutionary divergence times

Area of Science:

• Systematics and evolutionary biology
• Phylogenetics and molecular evolution
• Paleontology and evolutionary timescales

Background:

• Matrices of morphological characters are commonly used in systematics for dating species divergence times.
• Studies often combine morphological and molecular data, including extinct taxa, for divergence time inference.
• The concordance between morphological and molecular data for estimating divergence times requires investigation.

Purpose of the Study:

• To investigate the concordance of species divergence dates inferred using discrete morphological data versus molecular data.
• To determine if morphological data can produce time estimates that are concordant with molecular data.
• To justify the use of morphological characters alongside molecular data in divergence time inference.

Main Methods:

• Systematic analysis of three empirical datasets from different species groups.
• Testing concordance of species divergence dates inferred using molecular and discrete morphological data from extant taxa.
• Comparison of divergence time estimates, branch lengths, and node-to-tip distances between morphological and molecular data.

Main Results:

• A high correlation was found between divergence time estimates from molecular and morphological data.
• Node-to-tip distances showed higher correlation than branch lengths due to averaging effects over multiple branches.
• Discordance can occur, with some intermediate nodes showing significant time differences between data types.

Conclusions:

• Node- and tip-calibration approaches may be more suitable for nodes with numerous taxa.
• Evaluating the intrinsic time structure concordance between morphological and molecular data is crucial before combined dating analyses.
• Findings support the utility of morphological data in divergence time estimation when assessed for concordance with molecular data.