Living fossils are extant organisms that are ancient in origin, have a relict distribution, and retain ancestral morphological features. These organisms usually have low taxonomic diversity and isolated systematic positions, and are often endangered or in urgent need of protection. However, the molecular evolution and ecological properties of living fossils, especially plant living fossils, are still poorly understood.
The team of Wang Wei, a researcher at the Institute of Botany, Chinese Academy of Sciences (CAS), et al. studied the molecular evolutionary rate and its mechanism by integrating phylogenetic genomics, comparative genomics, and ecological niche simulation with the living fossil plant, the collocarpaceae (Eupteleaceae), which originated in the Cretaceous period. . The researchers assembled the first high-quality, chromosome-level nuclear genome of the Collocarpaceae, as well as chloroplast and mitochondrial genomes. The results show that among the Ranunculales, the basal group of true dicotyledons, the Collinaceae were the first to diverge and share an ancient genome-wide duplication event with other Ranunculales species. The three sets of genomes in Ranunculales, as well as the genes with different functions within the same genome, have extremely low rates of molecular evolution, which may be related to their conserved nuclear genome structure, woody habits, and conserved ecological niche requirements. In addition, it was found that the early divergent clades of the buttercup order as well as other basal true dicotyledonous plant taxa were involved in the Early Cretaceous terrestrial revolution.
This study reveals how living fossil plants evolved and adapted in response to large-scale environmental changes, providing new insights into the diversification of early true dicotyledons, and analytical strategies integrating phylogeny, comparative genomics, and ecological niche modeling can be used to study the molecular evolution of other living fossil plants and their mechanisms.
The related research results were recently published online in SCIENCECHINA Life Sciences. The research was supported by the Strategic Pilot Project of the Chinese Academy of Sciences and the National Natural Science Foundation of China.
Phytomorphology, distribution and genome assembly results of the Collocarpaceae family
