Fig. 3. A model of the polyploidization–rediploidization process in plants during global climate change.

a Whole-genome triplication (γ-WGT and α^S-WGT) events coincide with dramatic global climate changes. The sea level rise, massive extinction, and WGT event might provide the opportunity for the offshore woody plants to survive, leading to the emergence of the mangrove. The images portray the prevalent environments during various periods. In the Early Cretaceous (around 120 Mya), an arid climate prevailed⁴⁷. At the K-Pg boundary (around 66 Mya), the dramatic global climate change following a significant asteroid collision with Earth⁴⁸. During the PETM (around 55 Mya), there was a notable global temperature increase and a rise in eustatic sea levels⁷². Finally, the image depicts the current environment. The cartoon elements have been sourced and modified from materials contributed by Christine Thurber, Dieter Tracey, Jane Hawkey, Jane Thomas, and Tracey Saxby (available in the IAN Image Library at https://ian.umces.edu/media-library/) under a CC BY-SA 4.0 License. Detailed credits for these cartoon materials can be found in Supplementary Data 2. b A hypothetical model of polyploidization–rediploidization process. The initial diploid genome experiences whole-genome triplication around the period of dramatic global environment and climate change. Polyploidy may persist during this period. Rediploidization post polyploidization is a major process for polyploids, driving the genome toward a diploid state through divergence of homologous genes in terms of sequence and expression, redundancy reductions, and large chromosome rearrangements such as fusion and fission events. The round of polyploidization and rediploidization process is widespread in angiosperms. The brown chromosomes represent homologous chromosomes, while the red and blue chromosomes represent significantly diverged chromosomes. The yellow bands indicate regions derived from other ancestral chromosomes through chromosomal rearrangements.