College of Life Sciences, Nanjing Normal University, Nanjing, China.
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.
Mol Biol Evol. 2021 Jul 29;38(8):3332-3344. doi: 10.1093/molbev/msab106.
The relationships among the four major embryophyte lineages (mosses, liverworts, hornworts, vascular plants) and the timing of the origin of land plants are enigmatic problems in plant evolution. Here, we resolve the monophyly of bryophytes by improving taxon sampling of hornworts and eliminating the effect of synonymous substitutions. We then estimate the divergence time of crown embryophytes based on three fossil calibration strategies, and reveal that maximum calibration constraints have a major effect on estimating the time of origin of land plants. Moreover, comparison of priors and posteriors provides a guide for evaluating the optimal calibration strategy. By considering the reliability of fossil calibrations and the influences of molecular data, we estimate that land plants originated in the Precambrian (980-682 Ma), much older than widely recognized. Our study highlights the important contribution of molecular data when faced with contentious fossil evidence, and that fossil calibrations used in estimating the timescale of plant evolution require critical scrutiny.
四大大胚植物谱系（苔藓、地钱、角苔、维管植物）之间的关系以及陆地植物起源的时间是植物进化中的一个谜。在这里，我们通过改进角苔类植物的分类群采样并消除同义替换的影响来解决苔藓植物的单系性。然后，我们基于三种化石校准策略来估计冠胚植物的分歧时间，并揭示最大校准约束对估计陆地植物起源时间有重大影响。此外，先验和后验的比较为评估最佳校准策略提供了指导。通过考虑化石校准的可靠性和分子数据的影响，我们估计陆地植物起源于前寒武纪（980-682 Ma），比广泛认为的要古老得多。我们的研究强调了在面对有争议的化石证据时分子数据的重要贡献，并且用于估计植物进化时间尺度的化石校准需要仔细审查。
