Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach
Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach
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DOI：
10.1038/s41598-020-59524-z
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发表时间：
2020-02-13
影响因子：
4.6
通讯作者：
Guillou, Laure
中科院分区：
文献类型：
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作者：
Cai, Ruibo;Kayal, Ehsan;Guillou, Laure
海洋原生生物作为重要的有机物初级生产者和回收者，其多样性已通过高通量条形码测序得到广泛研究。然而，短的元巴编码序列到传统的分类单位的分类是不平凡的，特别是对于主要由其遗传指纹已知的谱系。这是广泛分布的角变形虫种复合体的情况，它们是甲藻同源物的寄生虫。我们使用的遗传和表型特征，适用于119个Amoebophrya个人从同一地理区域采样，构建实用的指导方针，可应用于基于DNA/RNA的多样性分析的物种划分。基于内部转录间隔区（ITS）区域，ITS 2补偿碱基变化（CBC）和基因组k-mer比较，我们明确定义了8个神秘的物种密切相关的核糖体类型，其SSU rDNA的序列同一性小于97%。然后，我们在对Alexandrum minutum开花的三年调查中跟踪了这些寄生物种的遗传特征。结果表明，这些隐生变形虫种共同发生，并共享相同的生态位。我们还观察到一个最大的生态适合寄生虫具有狭窄的中间宿主范围，反映了较高的成本感染更广泛的主机范围。这项研究表明，一个完整的分类修订这些寄生甲藻是早就应该了解他们的多样性和生态作用的海洋浮游生物。
As critical primary producers and recyclers of organic matter, the diversity of marine protists has been extensively explored by high-throughput barcode sequencing. However, classification of short metabarcoding sequences into traditional taxonomic units is not trivial, especially for lineages mainly known by their genetic fingerprints. This is the case for the widespread Amoebophrya ceratii species complex, parasites of their dinoflagellate congeners. We used genetic and phenotypic characters, applied to 119 Amoebophrya individuals sampled from the same geographic area, to construct practical guidelines for species delineation that could be applied in DNA/RNA based diversity analyses. Based on the internal transcribed spacer (ITS) regions, ITS2 compensatory base changes (CBC) and genome k-mer comparisons, we unambiguously defined eight cryptic species among closely related ribotypes that differed by less than 97% sequence identity in their SSU rDNA. We then followed the genetic signatures of these parasitic species during a three-year survey of Alexandrium minutum blooms. We showed that these cryptic Amoebophrya species co-occurred and shared the same ecological niche. We also observed a maximal ecological fitness for parasites having narrow to intermediate host ranges, reflecting a high cost for infecting a broader host range. This study suggests that a complete taxonomic revision of these parasitic dinoflagellates is long overdue to understand their diversity and ecological role in the marine plankton.