Data_Sheet_1_Comparative Analysis of Chloroplast Genomes of Seven Chaetoceros Species Revealed Variation Hotspots and Speciation Time.docx

Chaetoceros is a species-rich diatom genus with broad distribution and plays an important role in global carbon cycle and aquatic ecosystems. However, genomic information of Chaetoceros species is limited, hindering advanced researches on Chaetoceros biodiversity and their differential impact on ecology. In this study, we constructed full-length chloroplast genomes (cpDNAs) for seven Chaetoceros species, including C. costatus, C. curvisetus, C. laevisporus, C. muelleri, C. pseudo-curvisetus, C. socialis, and C. tenuissimus. All of these cpDNAs displayed a typical quadripartite structure with conserved genome arrangement and specific divergence. The sizes of these cpDNAs were similar, ranging from 116,421 to 119,034 bp in size, and these cpDNAs also displayed similar GC content, ranging from 30.26 to 32.10%. Despite extensive synteny conservation, discrete regions showed high variations. Divergence time estimation revealed that the common ancestor of Chaetoceros species, which formed a monophyletic clade at approximately 58 million years ago (Mya), split from Acanthoceras zachariasii at about 70 Mya. The availability of cpDNAs of multiple Chaetoceros species provided valuable reference sequences for studying evolutionary relationship among Chaetoceros species, as well as between Chaetoceros species and other diatom species.

Chaetoceros（角藻属）是一种物种丰富的硅藻属，分布广泛，在全球碳循环和淡水生态系统中扮演着至关重要的角色。然而，Chaetoceros物种的基因组信息有限，这阻碍了对其生物多样性和对生态系统的差异化影响进行深入研究。在本研究中，我们构建了包括C. costatus、C. curvisetus、C. laevisporus、C. muelleri、C. pseudo-curvisetus、C. socialis和C. tenuissimus在内的七个Chaetoceros物种的全长叶绿体基因组（cpDNAs）。这些cpDNAs均展现出典型的四分体结构，具有保守的基因组排列和特定的差异。这些cpDNAs的尺寸相似，大小介于116,421至119,034碱基对之间，且这些cpDNAs的GC含量也相似，介于30.26至32.10%之间。尽管存在广泛的同源保守性，离散区域却表现出高度变异。分歧时间估计显示，Chaetoceros物种的共同祖先约在5800万年前（百万年前）形成一个单系群，并大约在7000万年前从Acanthoceras zachariasii中分离出来。多个Chaetoceros物种的cpDNAs的可获得性为研究Chaetoceros物种之间的进化关系，以及Chaetoceros物种与其他硅藻物种之间的进化关系提供了宝贵的参考序列。