Morphospecies versus Phylospecies Concepts for Evaluating Phytoplankton Diversity: The Case of the Coccolithophores
Morphospecies versus Phylospecies Concepts for Evaluating Phytoplankton Diversity: The Case of the Coccolithophores
复制标题
评估浮游植物多样性的形态种与系统种概念：以颗石藻为例
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
C. Vargas
中科院分区：
文献类型：
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作者：
J. Young;Hui Liu;I. Probert;S. Aris;C. Vargas
摘要
遗传学方法来探索在现场海洋浮游植物组合揭示了以前未知的多样性在不同的分类水平。然而，系统发育物种的概念很少被比较，以经典的形态学为基础的分类，形成了最新的生态，生理和古生物学知识的浮游植物的基础。在这里，我们使用颗石藻作为案例研究，以测试这两个分类方法之间的关系。从三个水样（大西洋，太平洋和地中海）的217颗石藻LSU rDNA序列和729个标本的光镜和电镜观察分析表明，形态和遗传数据的平行分析突出了固有的局限性，每种方法。结合形态发生分析扩大了对天然颗石群落的组成、丰富度和结构的描述范围。总体而言，遗传确定的多样性超过形态确定的多样性，这可能部分反映了方法的偏差，但也可能反映了神秘的物种形成和/或存在的轻度或非钙化物种（或生命周期阶段）内的颗石藻分支。针对六颗石藻家族或目级亚群，我们发现，在不同的环境中，已建立的形态种内的遗传多样性变化显着。至关重要的是，我们发现，在不同的自然群落，一个因素，可能有重要的影响，相对于宏基因组学方法的多样性评价的分歧阈值，在该阈值对应于形态种。
Abstract
Genetic approaches to exploring in situ marine phytoplankton assemblages have revealed previously unsuspected diversity at different taxonomic levels. However, the phylogenetic species concept has rarely been compared to classical morphologically based taxonomy, which forms the basis of most current ecological, physiological, and paleontological knowledge of phytoplankton. Here we use the coccolithophores as a case study to test the relationship between these two taxonomic approaches. Analysis of 217 coccolithophore LSU rDNA sequences and 729 specimens observed by light and electron microscopy obtained from three water samples (Atlantic Ocean, Pacific Ocean and Mediterranean Sea) demonstrated that parallel analysis of morphological and genetic data highlights limitations inherent to each approach. Combined morpho-genetic analyses increase the scope of description of the composition, richness and structure of natural coccolithophore communities. Overall, genetic determined diversity exceeded morphological determined diversity, which may partly reflect methodological biases, but also probably reflects cryptic speciation and/or the presence of lightly- or non-calcifying species (or life cycle stages) within the coccolithophore clade. Focusing on six coccolithophore family or order level subgroups, we show that the genetic diversity within established morphospecies varied significantly in different environments. Critically, we find that the divergence threshold at which phylospecies corresponded to morphospecies varied between different natural communities, a factor that may have important implications with respect to evaluation of diversity by metagenomics approaches.