Foliose Ulva spp. have become increasingly important worldwide for their environmental and financial impacts. A large number of such Ulva species have rapid reproduction and proliferation habits, which explains why they are responsible for Ulva blooms, known as “green tides”, having dramatic negative effects on coastal ecosystems, but also making them attractive for aquaculture applications. Despite the increasing interest in the genus Ulva, particularly on the larger foliose species for aquaculture, their inter‐ and intra‐specific genetic diversity is still poorly described. We compared the cytoplasmic genome (chloroplast and mitochondrion) of 110 strains of large distromatic foliose Ulva from Ireland, Brittany (France), the Netherlands and Portugal. We found six different species, with high levels of inter‐specific genetic diversity, despite highly similar or overlapping morphologies. Genetic variation was as high as 82 SNPs/kb between Ulva pseudorotundata and U. laetevirens, indicating considerable genetic diversity. On the other hand, intra‐specific genetic diversity was relatively low, with only 36 variant sites (0.03 SNPs/kb) in the mitochondrial genome of the 29 Ulva rigida individuals found in this study, despite different geographical origins. The use of next‐generation sequencing allowed for the detection of a single inter‐species hybrid between two genetically closely related species, U. laetevirens, and U. rigida, among the 110 strains analyzed in this study. Altogether, this study represents an important advance in our understanding of Ulva biology and provides genetic information for genomic selection of large foliose strains in aquaculture.

中文翻译：

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叶糖Ulva物种显示出相当大的种间遗传多样性，低种内遗传变异以及在野生环境中种间杂种的罕见发生

叶糖Ulva spp。在全球范围内因其对环境和经济的影响而变得越来越重要。许多这类Ulva物种具有快速繁殖和繁殖的习性，这解释了为什么它们对Ulva盛开负有责任，被称为“绿潮”，对沿海生态系统产生了巨大的负面影响，但也使其对水产养殖应用具有吸引力。尽管人们对Ulva属的兴趣日益浓厚，特别是对于较大的水产养殖叶酸品种，但它们的种间和种内遗传多样性仍然很少得到描述。我们比较了110株大型两性叶状Ulva菌株的细胞质基因组（叶绿体和线粒体）来自爱尔兰，布列塔尼（法国），荷兰和葡萄牙。我们发现了六种不同的物种，尽管形态高度相似或重叠，但种间遗传多样性却很高。Ulva pseudorotundata和U之间的遗传变异高达82 SNPs / kb 。laetevirens，表明相当的遗传多样性。另一方面，种内遗传多样性相对较低，尽管地理来源不同，但在该研究中发现的29个乌Ul种群的线粒体基因组中仅有36个变异位点（0.03 SNPs / kb）。利用下一代测序技术，可以检测到两个遗传密切相关的物种U之间的单一种间杂种。laetevirens和ü。杜松，在这项研究分析了110株之间。总而言之，这项研究代表了我们对Ulva生物学的理解的重要进展，并为水产养殖中大型叶糖菌株的基因组选择提供了遗传信息。