Espanhol Rute, Almeida Pedro R, Alves M Judite
Instituto de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
Mol Ecol. 2007 May;16(9):1909-24. doi: 10.1111/j.1365-294X.2007.03279.x.
A remarkable trend in the evolution of lampreys is the occurrence in most genera of 'paired species', in which the parasitic anadromous lampreys are believed to have given rise to nonparasitic freshwater resident populations. The present work examines the phylogeography of the European paired species Lampetra fluviatilis and Lampetra planeri, in an attempt to elucidate species pair evolutionary history. We studied sequence variation in cytochrome b and ATPase 6, 8 mitochondrial genes in 63 individuals from 21 localities of the paired species throughout their distribution range. Results from the phylogenetic and nested clade analyses were largely consistent, suggesting the existence of three major evolutionary lineages: lineage I and possibly lineage II are widespread throughout Europe, while the most ancestral lineage III is apparently restricted to the Iberian Peninsula. The high genetic diversity observed in the Iberian Peninsula is probably the result of refugial persistence and subsequent accumulation of variation over several ice ages, whereas the low levels of genetic diversity observed in central and northern Europe should reflect a rapid postglacial colonization. Results suggest that L. planeri originated within at least two distinct evolutionary lineages, rejecting the single origin hypothesis. The observed lack of taxa monophyly within lineage I may be the result of ongoing gene flow if the two taxa are alternate life-history forms of a single species. However, structure within lineage I is also consistent with the hypothesis of divergence of taxa after postglacial dispersion (around 2000 generations ago) with incomplete lineage sorting. Further testing of the alternative hypotheses is warranted.
七鳃鳗进化过程中的一个显著趋势是，大多数属中出现了“配对物种”，据信寄生性溯河产卵七鳃鳗产生了非寄生性淡水定居种群。本研究考察了欧洲配对物种河七鳃鳗和溪流七鳃鳗的系统地理学，试图阐明物种对的进化历史。我们研究了来自配对物种21个地点的63个个体的细胞色素b和ATPase 6、8线粒体基因的序列变异，这些个体分布在其整个分布范围内。系统发育分析和嵌套进化枝分析的结果基本一致，表明存在三个主要进化谱系：谱系I以及可能的谱系II在欧洲广泛分布，而最原始的谱系III显然局限于伊比利亚半岛。在伊比利亚半岛观察到的高遗传多样性可能是几个冰河时代避难所持续存在以及随后变异积累的结果，而在欧洲中部和北部观察到的低遗传多样性水平应反映了冰期后的快速殖民化。结果表明，溪流七鳃鳗至少起源于两个不同的进化谱系，这否定了单一起源假说。如果这两个分类单元是单一物种的交替生活史形式，那么在谱系I中观察到的分类单元非单系性可能是正在进行的基因流动的结果。然而，谱系I中的结构也与冰期后扩散（约2000代以前）后分类单元分化且谱系分选不完全的假说一致。有必要对这些替代假说进行进一步检验。
