Chloroplast phylogenomics of unicellular and colonial Volvocales provides perspectives on the evolution of morphological characters  

作　　者：Xi Li Xuan Shi Hong Cheng Shi-Yu Zhang Zhi-Ping Yang Xiao-Ya Ma Bo-Jian Zhong 

机构地区：[1]College of Life Sciences,Nanjing Normal University,Nanjing 210023,China

出　　处：《Journal of Systematics and Evolution》2023年第1期127-142,共16页植物分类学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.31970229 and No.32122010);Shenzhen Key Laboratory of Southern Subtropical Plant Diversity,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD);the China Postdoctoral Science Foundation Grant(No.2018M632329).

摘　　要：Volvocales forms a species-rich clade with wide morphological variety and is regarded as an ideal model for tracing the evolutionary transitions in multicellularity.The phylogenetic relationships among the colonial volvocine algae and its relatives are important for investigating the origin of multicellularity in the clade Reinhardtinia.Therefore,a robust phylogenetic framework of the unicellular and colonial volvocine algae with broad taxon and gene sampling is essential for illuminating the evolution of multicellularity.Recent chloroplast phylogenomic studies have uncovered five major orders in the Chlorophyceae,but the family-level relationships within Sphaeropleales and Volvocales remain elusive due to the uncertain positions of some incertae sedis taxa.In this study,we contributed six newly sequenced chloroplast genomes in the Volvocales and analyzed a dataset with 91 chlorophycean taxa and 58 protein-coding genes.Conflicting phylogenetic signals were detected among chloroplast genes that resulted in discordant tree topologies among different analyses.We compared the phylogenetic trees inferred from original nucleotide,RY-coding,codon-degenerate,and amino acid datasets,and improved the robustness of phylogenetic inference in the Chlorophyceae by reducing base compositional bias.Our analyses indicate that the unicellular Chlamydomonas and Vitreochlamys are close to or nested within the colonial taxa,and all the incertae sedis taxa are nested within the monophyletic Sphaeropleales s.l.We propose that the colonial taxa in the Reinhardtinia are paraphyletic and multicellularity evolved once in the volvocine green algae and might be lost in Chlamydomonas and Vitreochlamys.

关 键 词：CHLOROPHYCEAE chloroplast phylogenomics compositional heterogeneity MULTICELLULARITY VOLVOCALES 

分 类 号：Q94[生物学—植物学]