Molecular Dating of the Teleost Whole Genome Duplication (3R) Is Compatible With the Expectations of Delayed...

Area of Science:

• Evolutionary Biology
• Genomics
• Paleontology

Background:

• Whole genome duplication (WGD) events are linked to vertebrate phenotypic evolution and diversification.
• The 3R WGD is particularly significant, preceding the origin of teleost fishes, which constitute over half of vertebrate species.
• Establishing the precise timing of WGD events and subsequent diversification is crucial for testing causal relationships.

Purpose of the Study:

• To molecularly date the 3R whole genome duplication event in teleost fishes.
• To determine the temporal relationship between the 3R WGD and the divergence of crown-teleosts and major teleost radiations.
• To assess the role of the 3R WGD as a driver of teleost diversification.

Main Methods:

• Molecular clock dating was employed using concatenated gene alignments.
• Phylogenetic analysis was conducted to establish divergence times.
• Age constraints were calculated for the 3R WGD, crown-teleost divergence, and subsequent diversification events.

Main Results:

• The 3R WGD occurred in the early-middle Permian (286.18–267.20 Ma).
• Crown-teleost divergence occurred significantly later, in the latest Permian-earliest Late Triassic (254.36–234.16 Ma).
• Major teleost diversification pulses (Ostariophysi, Percomorpha) occurred 56–183 Myr after the 3R WGD.

Conclusions:

• A substantial temporal gap exists between the 3R WGD and teleost diversification, precluding 3R as a deterministic driver.
• The timing is compatible with a prolonged rediploidization process following WGD.
• Rediploidization, involving chromosome rearrangement and gene loss, remains a viable mechanism for teleost novelty and diversification.