Geographic structure, genetic diversity and source tracking of Spartina alterniflora
Geographic structure, genetic diversity and source tracking of Spartina alterniflora
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DOI：
10.1111/j.1365-2699.2007.01764.x
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发表时间：
2007-12-01
影响因子：
3.9
通讯作者：
Strong, Donald R.
中科院分区：
文献类型：
--
作者：
Blum, Michael J.;Bando, K. Jun;Strong, Donald R.
目的研究互花米草（Spartina alterniflora）在本地的遗传变异分布和结构，探讨外来互花米草（Spartina alterniflora）成功的进化机制。互花米草。分布于北美大西洋、墨西哥湾和太平洋沿岸沿着的潮间沼泽。方法采用amova、简约性分析、叶绿体DNA（cpDNA）序列单倍型网络、邻居连接分析、种群结构的贝叶斯分析和个体分配测试。结果发现本地互花米草的基因流动水平较低，遗传变异的地理模式也较低。产于北美大西洋和海湾沿岸的一个互花米草属。cpDNA单倍型的分布表明，大西洋沿岸的S.互花米草又分为"北方"和"南方"类群。在微卫星位点观察到的变异进一步表明，中大西洋S。alterniflora与S.产于大西洋南部和新英格兰沿海沼泽地的一种互花米草。在大西洋和海湾沿岸的本地人口和非本地太平洋沿岸人口之间的比较证实了先前的研究，证明在旧金山弗朗西斯科湾种间杂交互惠。我们的结果证实了历史证据，S。互花米草是从多个来源种群引入到威拉帕湾的。然而，我们发现，一些威拉帕湾S。互花米草在遗传上与假定的来源不同，可能是由于以前异地的本地种群之间的二次接触后的混合物。我们进一步恢复了支持模型的证据，表明S。互花米草在华盛顿州内从威拉帕湾扩散到格雷港。互花天然S.互花米草可能是地理省之间的环境差异、迁移障碍或对历史条件的响应的结果。这些因素之间的相互作用，而不是一个单一的因素，可能最好地解释了分布的遗传变异之间的本地S。互花对本地种群和外来种群进行全面的遗传比较，可以说明生物入侵是如何由截然不同的潜在因素造成的--其中一些因素可能无法识别。证明入侵可以由几个独立或相互作用的机制引起，对于改善风险评估和未来预测非常重要。对S.互花米草不仅可以阐明是什么力量构成了本地种群，而且还可以通过使引入后的遗传变化和生活史性状的快速进化得到更成功的利用来改善对外来种群的管理。
Aim To examine the distribution and structure of genetic variation among native Spartina alterniflora and to characterize the evolutionary mechanisms underlying the success of non-native S. alterniflora.Location Intertidal marshes along the Atlantic, Gulf and Pacific coasts of North America.Methods amova, parsimony analysis, haplotype networks of chloroplast DNA (cpDNA) sequences, neighbour-joining analysis, Bayesian analysis of population structure, and individual assignment testing were used.Results Low levels of gene flow and geographic patterns of genetic variation were found among native S. alterniflora from the Atlantic and Gulf coasts of North America. The distribution of cpDNA haplotypes indicates that Atlantic coast S. alterniflora are subdivided into 'northern' and 'southern' groups. Variation observed at microsatellite loci further suggests that mid-Atlantic S. alterniflora are differentiated from S. alterniflora found in southern Atlantic and New England coastal marshes. Comparisons between native populations on the Atlantic and Gulf coasts and non-native Pacific coast populations substantiate prior studies demonstrating reciprocal interspecific hybridization in San Francisco Bay. Our results corroborate historical evidence that S. alterniflora was introduced into Willapa Bay from multiple source populations. However, we found that some Willapa Bay S. alterniflora are genetically divergent from putative sources, probably as a result of admixture following secondary contact among previously allopatric native populations. We further recovered evidence in support of models suggesting that S. alterniflora has secondarily spread within Washington State, from Willapa Bay to Grays Harbor.Main conclusions Underlying genetic structure has often been cited as a factor contributing to ecological variation of native S. alterniflora. Patterns of genetic structure within native S. alterniflora may be the result of environmental differences among biogeographical provinces, of migration barriers, or of responses to historical conditions. Interactions among these factors, rather than one single factor, may best explain the distribution of genetic variation among native S. alterniflora. Comprehensive genetic comparisons of native and introduced populations can illustrate how biological invasions may result from dramatically different underlying factors - some of which might otherwise go unrecognized. Demonstrating that invasions can result from several independent or interacting mechanisms is important for improving risk assessment and future forecasting. Further research on S. alterniflora not only may clarify what forces structure native populations, but also may improve the management of nonnative populations by enabling post-introduction genetic changes and the rapid evolution of life-history traits to be more successfully exploited.