Constraining Whole-Genome Duplication Events in Geological Time

Area of Science:

• Evolutionary Biology
• Genomics
• Paleontology

Background:

• The timing of whole-genome duplication (WGD) events is critical for understanding their evolutionary impact.
• Hypotheses link WGD to increased biological diversity and complexity, necessitating methods to date these events relative to macroevolutionary outcomes.

Purpose of the Study:

• To present best practices for estimating the absolute timing of WGD events using molecular clock methods.
• To demonstrate the application of these methods using MCMCtree with a case study in flowering dogwoods (Cornus).

Main Methods:

• Utilizing molecular clock methods to estimate absolute divergence times.
• Employing the MCMCtree program for phylogenetic dating.
• Constructing robust fossil calibrations to account for paleontological uncertainties.

Main Results:

• The study outlines a methodology for dating WGD events and subsequent speciation.
• In flowering dogwoods, the WGD event was found to predate the end-Cretaceous mass extinction.
• The WGD event and the mass extinction in this lineage appear to be independent.

Conclusions:

• The presented approach enables the exploration of the relationship between WGD and macroevolutionary patterns.
• Accurate dating of WGD events is crucial for testing hypotheses about their role in evolutionary innovation.
• The findings in Cornus suggest that WGD can occur independently of major extinction events.