Host-Calibrated Time Tree Caps the Age of Giant Viruses

Area of Science:

• Virology
• Evolutionary Biology
• Genomics

Background:

• Viruses significantly impact public health, economies, and ecosystems.
• The origins, ages, and early host-parasite evolutionary dynamics of viruses remain largely unknown.

Purpose of the Study:

• To infer the evolutionary timescale and host-associated divergence times of eukaryotic giant DNA viruses (phylum Nucleocytoviricota).
• To investigate the evolutionary history and host-shift dynamics of this major viral group.

Main Methods:

• Phylogenetic dating analyses were employed, calibrated using the ages of host taxa for specific virus lineages.
• Maximum divergence times for Nucleocytoviricota were estimated.

Main Results:

• The last common ancestor of Nucleocytoviricota emerged after 1,000 million years ago, indicating a later origin than eukaryotes.
• Giant virus evolution coincided with or postdated the Neoproterozoic oxygenation event.
• Diversification was linked to host shifts, including two transitions from amoebozoans to animals, preceding iridoviruses and African swine fever viruses within the last 450 million years.

Conclusions:

• This study provides an evolutionary timeline for a major group of giant viruses.
• Findings are crucial for understanding virus-host interactions, evolutionary pathways, and ecological roles throughout Earth's history.