Reproductive isolation among sympatric cryptic species in marine diatoms
Reproductive isolation among sympatric cryptic species in marine diatoms
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DOI：
10.1016/j.protis.2006.10.001
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发表时间：
2007-04-01
期刊：
影响因子：
2.5
通讯作者：
Montresor, Marina
中科院分区：
文献类型：
--
作者：
Amato, Alberto;Kooistra, Wiebe H. C. F.;Montresor, Marina
拟菱形藻是一种海洋世界性的链形浮游硅藻属。对于绝大多数浮游植物而言，本属内的物种鉴定主要依赖于形态特征。分类群最初是根据细胞形状和它们的复合二氧化硅细胞壁（称为硅藻壳）的总体形态来识别的。然而，在电子显微镜下观察的硅藻壳显示了许多额外的字符的物种鉴定和分子研究的结果表明，遗传上不同的群体可能存在于形态种。然而，这些研究并没有解决这些遗传差异的生物学意义。在这里，我们通过比较95株菌株的超微结构特征和序列数据（三个核糖体和一个质体标记）与这些菌株之间的交配实验结果来弥合这一差距。实验在两种形态上不同的实体上进行：P. delicatissima和P pseudodelicatissima。这两个实体中的每一个都由多个遗传上不同和生殖上隔离的类群组成，所有这些类群都发生在同域性中：P delicatissima由三个系统发育和生殖上不同的类群组成，而P. pseudodelicatissima由多达五个类群组成。一旦这些分类群已被定义在遗传和生物学上，细微的超微结构的差异也可以检测到。我们的研究结果不仅表明，隐藏的遗传变异丰富的同域，而且它们是生殖隔离，因此，生物学上不同的单位。(C)2006年Elsevier GmbH。All rights reserved.
Pseudo-nitzschia is a marine cosmopolitan genus of chain-forming planktonic diatoms. As for the vast majority of phytoplankton organisms, species identification within this genus mostly relies upon morphological features. Taxa were initially identified based on cell shape and gross morphology of their composite silica cell wall, called the frustule. Yet, observations of the frustule in electron microscopy showed many additional characters for species identification and results of molecular studies have demonstrated that genetically distinct groups might exist within morpho-species. However, these studies have not addressed the biological meaning of these genetic differences. Here, we bridge that gap by comparing ultrastructural features and sequence data (three ribosomal and one plastid marker) of 95 strains with results of mating experiments among these strains. Experiments were performed on two morphologically distinct entities: P. delicatissima and P pseudodelicatissima. Each of the two entities consisted of multiple genetically distinct and reproductively isolated taxa, all occurring in sympatry: P delicatissima was composed of three phylogenetic and reproductively distinct groups, whereas P. pseudodelicatissima consisted of up to five. Once these taxa had been defined both genetically and biologically, subtle ultrastructural differences could be detected as well. Our findings not only show that cryptic genetic variants abound in sympatry, but also that they are reproductively isolated and, therefore, biologically distinct units. (C) 2006 Elsevier GmbH. All rights reserved.