Iterative Calibration: A Novel Approach for Calibrating the Molecular Clock Using Complex Geological Events

Area of Science:

• Evolutionary biology
• Molecular evolution
• Biogeography

Background:

• Molecular clocks are crucial for dating life's history, but calibration remains challenging, especially with limited fossil data.
• Biogeographic calibrations are often oversimplified, assuming simultaneous divergence across lineages.
• Accurate calibration is vital for robust molecular evolutionary analysis.

Purpose of the Study:

• To introduce a novel iterative calibration approach for molecular clocks.
• To enhance the accuracy of divergence dating by seeking congruence between geological history and allopatric divergences.
• To refine the dating of evolutionary events in Arctic marine life.

Main Methods:

• Developed and applied an iterative calibration method using 16 trans-Bering sister clades of echinoderms.
• Utilized complex geological events, like Bering Strait dynamics, for calibration.
• Employed Bayesian analysis to assess evolutionary rate variability in the COI-5P gene.

Main Results:

• The iterative calibration approach proved advantageous for dating complex geological events.
• Observed significant genetic divergence patterns in echinoderms, indicating multiple trans-Bering migrations.
• Proposed a molecular evolutionary rate of 2.8% pairwise Kimura-2-parameter sequence divergence per million years for the COI-5P gene in Northern echinoderms.

Conclusions:

• The iterative calibration method offers a powerful tool for molecular clock dating, applicable to various taxa and biogeographic systems.
• Evolutionary rates in the COI-5P gene for Northern echinoderms are largely clock-like.
• This study provides a refined context for understanding the evolutionary history of Arctic marine ecosystems.