ABSTRACT

The green seaweeds Ulva australis and U. pertusa were described from southern Australia and Japan, respectively. They are conspecific and U. australis, the currently accepted taxon, is native to temperate marine waters in north-eastern Asia, and known to be introduced overseas into Australasia, the Americas and Europe. Although the genetics of U. australis have been investigated elsewhere, along French coasts the origins and history of the introduction of this species need to be clarified. We used mitochondrial, plastid and nuclear markers to differentiate introduced populations of U. australis along the French Atlantic coasts. The plastid tufA gene used as a barcoding marker revealed a well-defined species with a higher haplotype diversity in native vs. introduced areas. The ITS2 region (nuclear) and rbcL (plastid) were used to compare French specimens with the lectotype of U. australis. Putative geographic origins of the genetically determined U. australis were examined using genetic markers with better resolution, the plastid atpI-H combined with the mitochondrial trnA-N. Origin(s) and introduction history of French specimens were inferred from the comparison between their haplotypes and those previously described in native and non-native temperate areas worldwide. Our results indicate that the presence of U. australis along the French Atlantic and Mediterranean coasts is the result of multiple introductions and independent pathways, and suggest that historical oyster transfers from Japan and British Columbia can only partially explain the observed patterns in genetic markers. Alternative hypotheses for the timing and pathways of introductions are proposed in the light of the historic background of maritime transport networks and trade between north-eastern Asia and Europe.

摘要

绿海藻Ulva australis和U. pertusa分别来自澳大利亚南部和日本。它们是同种的，目前公认的分类群U. australis原产于亚洲东北部的温带海洋水域，已知在海外被引入澳大利亚、美洲和欧洲。尽管在其他地方已经对澳大利亚的遗传学进行了调查，但在法国沿海地区，需要澄清该物种引入的起源和历史。我们使用线粒体、质体和核标记来区分沿法国大西洋沿岸引入的澳大利亚种群。质体凝灰岩用作条形码标记的基因揭示了一个明确定义的物种，在本地与. 介绍的领域。ITS2 区域（核）和rbc L（质体）用于比较法国标本与澳大利亚的选型。使用具有更好分辨率的遗传标记，即质体atp I-H 与线粒体trn A-N相结合，对遗传确定的U. australis 的假定地理起源进行了检查。法国标本的起源和引入历史是从它们的单倍型与先前在全球本土和非本土温带地区描述的单倍型之间的比较中推断出来的。我们的结果表明存在沿着法国大西洋和地中海沿岸的澳大利亚是多次引入和独立途径的结果，并表明从日本和不列颠哥伦比亚省的历史牡蛎转移只能部分解释观察到的遗传标记模式。根据海运网络和东北亚与欧洲之间贸易的历史背景，提出了引入时间和途径的替代假设。