ABSTRACT Xanthophyceae (Stramenopiles) are common microalgae in soil habitats, but not commonly known from maritime sandy habitats. Here we studied the genetic diversity of nine new isolates of Xanthophyceae from coastal habitats using two chloroplast-encoded markers. The isolates exhibited only three morphotypes. The sequence comparisons uncovered a respectable phylogenetic diversity, including novel infraspecific genotypes, among the isolates. The phylogenetic analyses of full rbcL gene sequences identified eight of the isolates to five named species based on monophyletic origins and short genetic distances with defined taxonomic reference strains. One strain, representing a coccoid species, was within a so far unrecognised lineage of Xanthophyceae. In four clades of the rbcL phylogeny, the coastal isolates were most closely related to strains from Antarctic soil habitats. Comparisons of the psbA/rbcL spacer region sequences, a highly variable molecular marker, uncovered a fine-scale structuring within a species which was consistent with habitat preferences. The new maritime isolates exhibited genotypes distinct from those of the same species from other habitats. It suggests that the environment selects for specific genotypes in these pioneering algae.

中文翻译：

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海洋沙质栖息地陆生黄藻科（原生藻菌）新分离株的基因型和系统发育多样性

摘要 黄藻科 (Stramenopiles) 是土壤栖息地中常见的微藻，但在海洋沙质栖息地中并不常见。在这里，我们使用两个叶绿体编码的标记研究了来自沿海栖息地的九个新分离株的黄藻科植物的遗传多样性。分离株仅表现出三种形态型。序列比较揭示了分离株之间可观的系统发育多样性，包括新的种下基因型。完整 rbcL 基因序列的系统发育分析基于单系起源和短遗传距离与定义的分类学参考菌株，将八个分离株鉴定为五个命名物种。一种代表球虫物种的菌株属于迄今为止未被认识的黄藻科谱系。在 rbcL 系统发育的四个进化枝中，沿海分离株与来自南极土壤栖息地的菌株最密切相关。psbA/rbcL 间隔区序列（一种高度可变的分子标记）的比较揭示了物种内与栖息地偏好一致的精细结构。新的海洋分离株表现出与来自其他栖息地的相同物种不同的基因型。这表明环境选择了这些先驱藻类中的特定基因型。