Data from: Genetics of a de novo origin of undifferentiated multicellularity

The evolution of multicellularity was a major transition in evolution and set the stage for unprecedented increases in complexity, especially in land plants and animals. Here we explore the genetics underlying a de novo origin of multicellularity in a microbial evolution experiment carried out on the green alga Chlamydomonas reinhardtii. We show that large-scale changes in gene expression underlie the transition to a multicellular life cycle. Among these, changes to genes involved in cell cycle and reproductive processes were overrepresented, as were changes to C. reinhardtii-specific and volvocine-specific genes. These results suggest that the genetic basis for the experimental evolution of multicellularity in C. reinhardtii has both lineage-specific and shared features, and that the shared features have more in common with C. reinhardtii’s relatives among the volvocine algae than with other multicellular green algae or land plants.

多细胞化的演化是演化史上的一次重大转型事件，为生物复杂性的空前跃升奠定了基础，这一效应在陆生植物与动物类群中表现得尤为突出。本研究以莱茵衣藻（Chlamydomonas reinhardtii）为实验对象开展微生物演化实验，旨在探究多细胞化从头起源背后的遗传调控机制。研究结果显示，向多细胞生活周期的转型，其核心分子基础是基因表达的大规模重塑。在这些发生表达变化的基因中，参与细胞周期与生殖过程的基因显著富集；莱茵衣藻特异性基因以及团藻亚目（volvocine）特异性基因的表达变化同样呈现富集趋势。上述结果表明，莱茵衣藻实验性演化出多细胞性状的遗传基础，同时兼具类群特异性与共有特征；其中共有特征与莱茵衣藻所属团藻亚目藻类的近缘类群更为接近，而非其他多细胞绿藻或陆生植物。