Phylogeography and Diversity Among Populations of the Toxigenic Benthic Dinoflagellate Prorocentrum From Coastal Reef Systems in Mexico
Phylogeography and Diversity Among Populations of the Toxigenic Benthic Dinoflagellate Prorocentrum From Coastal Reef Systems in Mexico
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DOI：
10.3389/fmars.2021.716669
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发表时间：
2021-10-15
影响因子：
3.7
通讯作者：
John, Uwe
中科院分区：
文献类型：
--
作者：
Cembella, Allan D.;Duran-Riveroll, Lorena M.;John, Uwe
海洋甲藻属原甲藻由许多物种组成，主要栖息于底栖或附生生境，特别是在热带和亚热带水域。尽管共同努力建立系统发育联系，但在定义形态种和物种复合体的成员方面仍然存在悬而未决的问题。本研究应用形态分类学、分子系统学和化学多样性的多元方法，研究了利马原甲藻和霍夫曼原甲藻复合体(PLSC和PHSC)的种间和种下关系，以建立多个克隆分离物之间的亲缘关系。形态分类学分析表明与经典的形态种描述符相一致，细胞大小和维度具有很高的可变性，但并不挑战当前物种复杂的概念。对来自加利福尼亚州海湾、加勒比海和墨西哥湾沿岸分离株的ITS/5.8S rDNA序列进行了系统发育分析，与GenBank存档的全球序列进行了比较，确定了五个一致的分支，并将PLSC和PHSC分开。基于补偿碱基改变(CBC)的ITS2 rRNA变异的二级结构建模在分辨各个物种复合体的细节方面是有效的，甚至由于潜在的杂交障碍而指示了可能的初始或隐蔽的物种形成。这项研究是最大的(n=67个分离株)与底栖甲藻属的腹泻性贝类中毒(DSP)相关的聚酮衍生毒素的化学多样性分析。一些类似物(OA、OA-D8、DTX1、DTX1a和DTX1a-D8)的相对组成，包括两个新的未描述的异构体，区别于P.lima和P.hoffmannianum Sensu Lato，但与底物类型或地理起源没有明显的联系。虽然所有利马疫霉和大多数霍夫曼氏疫霉(1个例外)都是产毒的，但总细胞毒素含量不能在物种水平上联系在一起。这项研究表明，毒素组成中的克隆化学多样性还不能有效地应用于确定生态位或局部组合内的物种相互作用。对ITS/5.8 rDNA进行系统发育分析，特别是与二级结构建模相结合，而不仅仅是比较LSU rDNA序列，是识别隐蔽物种形成和解析底栖甲藻种群内物种复合体的更有效的方法。
The marine dinoflagellate genus Prorocentrum Ehrenberg comprises many species occupying primarily benthic or epiphytic habitats, particularly in tropical and sub-tropical waters. Despite concerted efforts to establish phylogenetic associations, there remain unresolved issues in defining morphospecies and membership in species complexes. The study described herein addressed the inter- and infraspecific relationships of members of the Prorocentrum lima and Prorocentrum hoffmannianum species complexes (PLSC and PHSC, respectively) by applying multivariate approaches in morphotaxonomy, molecular phylogenetics and chemodiversity to establish affinities among multiple clonal isolates. Morphotaxonomic analysis showed consistency with classical morphospecies descriptors, and high variability in cell size and dimensions, but did not challenge current species complex concepts. Phylogenetic analysis of ITS/5.8S rDNA sequences from isolates from the Gulf of California, Caribbean Sea, and Gulf of Mexico coasts compared with archived global GenBank sequences served to define five consistent clades with separation of the PLSC and PHSC. Secondary structure modeling of ITS2 rRNA variation based on compensatory base changes (CBC) was effective in resolving details of the respective species complexes and even indicated putative incipient or cryptic speciation due to potential hybridization barriers. This study represents the largest (n = 67 isolates) chemodiversity analysis of polyketide-derived toxins associated with diarrheic shellfish poisoning (DSP) from a benthic dinoflagellate genus. Relative composition of some analogs (OA, OA-D8, DTX1, DTX1a, and DTX1a-D8), including two new undescribed isomers, distinguished P. lima from P. hoffmannianum sensu lato, but without clear associations with substrate type or geographical origin. Although all P. lima and most (one exception) P. hoffmannianum were toxigenic, the total cell toxin content could not be linked at the species level. This research demonstrates that clonal chemodiversity in toxin composition cannot yet be effectively applied to define ecological niches or species interactions within local assemblages. Phylogenetic analysis of the ITS/5.8 rDNA, particularly when combined with secondary structure modeling, rather than only a comparison of LSU rDNA sequences, is a more powerful approach to identify cryptic speciation and to resolve species complexes within benthic dinoflagellate groups.