Molecular investigations in populations of Spartina anglica C.E. Hubbard (Poaceae) invading coastal Brittany (France)
Molecular investigations in populations of Spartina anglica C.E. Hubbard (Poaceae) invading coastal Brittany (France)
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DOI：
10.1046/j.1365-294x.2001.01299.x
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发表时间：
2001-07-01
影响因子：
4.9
通讯作者：
Levasseur, JE
中科院分区：
文献类型：
--
作者：
Baumel, A;Ainouche, ML;Levasseur, JE
英国米草属是近代异倍体物种形成的一个典型例子。它是在19世纪末由英国本土的海米草和引进的美洲互花米草杂交而成的。杂交基因组（米草属x townsendii）的重复产生了一个充满活力的异源多倍体，参与了不同大陆的自然和人工入侵。英国米草属植物最早于1906年在法国被发现，从那时起，它就沿着法国西海岸传播开来。早期的研究表明，英国本土种群表现出一致的形态可塑性和缺乏同工酶变异。本文利用不同的分子标记（随机扩增的多态性DNA、单核苷酸重复序列以及核和叶绿体DNA序列的限制性内切模式）分析了英李法国居群的遗传模式。我们的研究结果表明，法国人群主要由一种“主要”多位点基因型组成。该基因型与来自英国的第一代杂交品种S. x townsendii相同。观察到该基因型的少数标记丢失，但仅限于布列塔尼的少数种群；它们很可能是在被引入之后独立出现的。在布列塔尼南部，没有发现S. anglica和S. maritima在两个物种共存的地方杂交。所有的法国种群都显示出与互花苜蓿相同的叶绿体DNA序列，互花苜蓿是母系基因组供体。这些发现与物种形成时严重的遗传瓶颈相一致，这是物种独特起源的结果。这两个亲本核序列都存在于异源多倍体种群中，表明所调查的标记在这个年轻物种中没有发生广泛的变化。
Spartina anglica is a classical example of recent alloploid speciation. It arose during the end of the nineteenth century in England by hybridization between the indigenous Spartina maritima and the introduced East-American Spartina alterniflora. Duplication of the hybrid genome (Spartina x townsendii) gave rise to a vigorous allopolyploid involved in natural and artificial invasions on different continents. Spartina anglica was first recorded in France in 1906, and since then, it has spread all along the western French coast. Earlier studies revealed that native British populations display consistent morphological plasticity and lack of isozyme variation. In this paper, we use different molecular markers (randomly amplified polymorphic DNA, intersimple sequence repeats and restriction patterns from nuclear and chloroplast DNA sequences) to analyse the genetic patterns of the French populations of S. anglica. Our results show that French populations are mainly composed of one 'major' multilocus genotype. This genotype is identical to the first-generation hybrid S. x townsendii from England. Losses of few markers from this genotype are observed but are restricted to a few populations from Brittany; it is likely that they appeared independently, subsequent to their introduction. In southern Brittany, no hybrids between S. anglica and S. maritima have been found where the two species co-occur. All French populations of S. anglica display the same chloroplast DNA sequences as S. alterniflora, the maternal genome donor. These findings are consistent with a severe genetic bottleneck at the time of the species formation, as a consequence of a unique origin of the species. Both parental nuclear sequences are present in the allopolyploid populations, revealing that for the markers investigated, no extensive changes have occurred in this young species.