Zardus John D, Hadfield Michael G
University of Hawaii, Kewalo Marine Lab, Honolulu, HI 96813 USA.
Mol Ecol. 2005 Oct;14(12):3719-33. doi: 10.1111/j.1365-294X.2005.02701.x.
Chthamalus proteus, a barnacle native to the Caribbean and western Atlantic, was introduced to the Pacific within the last few decades. Using direct sequencing of mitochondrial DNA (COI), we characterized genetic variation in native and introduced populations and searched for genetic matches between regions to determine if there were multiple geographical sources and introduction points for this barnacle. In the native range, we found great genetic differences among populations (max. F(ST) = 0.613) encompassing four lineages: one endemic to Panama, one endemic to Brazil, and two occurring Caribbean-wide. All four lineages were represented in the Pacific, but not equally; the Brazilian lineage was most prevalent and the Panamanian least common. Twenty-one individuals spread among nearly every island from where the barnacle is known in the Pacific, exactly matched six haplotypes scattered among Curaçao, the Netherlands Antilles; St John, US Virgin Islands; Puerto Rico; and Brazil, confirming a multigeographical origin for the Pacific populations. Significant genetic differences were also found in introduced populations from the Hawaiian Islands (F(CT) = 0.043, P < 0.001), indicating introduction events have occurred at more than one locality. However, the sequence, timing and number of arrival events remains unknown. Possible reasons for limited transport of this barnacle through the Panama Canal are discussed. This and a preponderance of Brazilian-type individuals in the Pacific suggest an unexpected route of entry from around Cape Horn, South America. Unification in the Pacific of historically divergent lineages of this barnacle raises the possibility for selection of 'hybrids' with novel ecological adaptations in its new environment.
多变小藤壶（Chthamalus proteus）是一种原产于加勒比海和西大西洋的藤壶，在过去几十年里被引入了太平洋。我们通过对线粒体DNA（COI）进行直接测序，对本地种群和引入种群的遗传变异进行了表征，并在不同区域寻找遗传匹配，以确定这种藤壶是否存在多个地理来源和引入点。在其原生范围内，我们发现不同种群之间存在很大的遗传差异（最大F(ST)=0.613），包括四个谱系：一个是巴拿马特有的，一个是巴西特有的，还有两个分布在整个加勒比地区。这四个谱系在太平洋地区都有代表，但分布不均；巴西谱系最为普遍，巴拿马谱系最不常见。在太平洋已知有这种藤壶的几乎每个岛屿上分布的21个个体，与散布在库拉索岛（荷属安的列斯群岛）、圣约翰岛（美属维尔京群岛）、波多黎各和巴西的六个单倍型完全匹配，证实了太平洋种群具有多个地理起源。在夏威夷群岛的引入种群中也发现了显著的遗传差异（F(CT)=0.043，P<0.001），这表明引入事件发生在不止一个地点。然而，引入事件的顺序、时间和数量仍然未知。我们讨论了这种藤壶通过巴拿马运河运输受限的可能原因。这种情况以及太平洋地区巴西型个体占优势表明，其进入的意外路线可能是从南美洲的合恩角附近。这种藤壶在历史上不同谱系在太平洋地区的统一，增加了在其新环境中选择具有新生态适应性的“杂交种”的可能性。
