Hidden diversity in the freshwater planktonic diatom Asterionella formosa
Hidden diversity in the freshwater planktonic diatom Asterionella formosa
复制标题
淡水浮游硅藻 Asterionella formosa 中隐藏的多样性
作者：
S. Wyngaert;S. Wyngaert;S. Wyngaert;M. Möst;M. Möst;M. Möst;Remo Freimann;B. Ibelings;B. Ibelings;B. Ibelings;P. Spaak;P. Spaak
许多淡水和海洋藻类物种被描述为具有世界性分布。这些广泛分布的形态相似的藻类是否也共享相似的基因库通常仍不清楚。在岛屿生物地理学理论的背景下，淡水湖泊典型的更强的空间隔离应该限制基因流动并导致湖泊之间更高的遗传分化。我们利用九个微卫星位点，研究了瑞士和荷兰不同湖泊中广泛分布的淡水浮游硅藻（Asterionella formosa）的遗传多样性。我们应用分层空间抽样设计来确定人口结构的地理尺度。另外还使用扩增片段长度多态性（AFLP）标记对分离株的子集进行了分析。我们的结果揭示了福尔摩沙复杂且意想不到的种群结构，同时有证据表明基因流受到限制和中等到高水平。通过多种多变量方法分析不同的遗传标记（微卫星和AFLP）一致表明，湖泊内的遗传分化比湖泊之间的遗传分化要强得多，这表明福尔摩沙中存在隐秘物种。我们的结论是，本研究中发现的隐藏多样性预计将对福尔摩沙在生物地理学、保护和生态研究中的进一步利用产生影响。有必要使用物种水平的系统发育标记进行进一步的研究，以便将观察到的分化置于物种形成的进化背景中。
Many freshwater and marine algal species are described as having cosmopolitan distributions. Whether these widely distributed morphologically similar algae also share a similar gene pool remains often unclear. In the context of island biogeography theory, stronger spatial isolation deemed typical of freshwater lakes should restrict gene flow and lead to higher genetic differentiation among lakes. Using nine microsatellite loci, we investigate the genetic diversity of a widely distributed freshwater planktonic diatom, Asterionella formosa, across different lakes in Switzerland and the Netherlands. We applied a hierarchical spatial sampling design to determine the geographical scale at which populations are structured. A subset of the isolates was additionally analysed using amplified fragment length polymorphism (AFLP) markers. Our results revealed complex and unexpected population structure in A. formosa with evidence for both restricted and moderate to high gene flow at the same time. Different genetic markers (microsatellites and AFLPs) analysed with a variety of multivariate methods consistently revealed that genetic differentiation within lakes was much stronger than among lakes, indicating the presence of cryptic species within A. formosa. We conclude that the hidden diversity found in this study is expected to have implications for the further use of A. formosa in biogeographical, conservation and ecological studies. Further research using species‐level phylogenetic markers is necessary to place the observed differentiation in an evolutionary context of speciation.