Park Joong-Ki, Lee Jun-Sang, Kim Won
School of Biological Sciences, Seoul National University, Korea.
Mol Cells. 2002 Oct 31;14(2):318-22.
Despite that the exotic invasion and rapid range expansion of Asian freshwater Corbicula into new environments have been of intensive research topic in freshwater ecology, the genetic structures of freshwater Corbicula in its native range remain poorly understood. In this study, the genetic structures of two Korean freshwater Corbicula clonal lineages were characterized by cross-referencing the nuclear genomic structures with mtDNA sequence analysis. In spite of substantial genetic differences (Nei's D = 0.363-0.372) and a pronounced level of fixed allelic distinctions (in six of 20 allozyme loci) between Corbicula lineages, no lineage-specific mtDNA differentiation was observed. The evident disjunction between mtDNA sequences and nuclear genomes is a compelling evidence for the existence of interspecific nuclear hybrid genome structures, comprising different combinations of paternal and maternal contributions. This unusual novel finding is the first case demonstrating that morphologically and allozymatically distinct, yet mitochondrially identical clonal lineages exist in the genus Corbicula. However, we could not find the ancestral species for these two clonal lineages in the present study, and the answer for this question must wait until the genetic structure of Asian Corbicula taxa is fully characterized.
尽管亚洲淡水蚬向新环境的外来入侵和快速分布范围扩张一直是淡水生态学中的一个深入研究课题，但淡水蚬在其原生范围内的遗传结构仍知之甚少。在本研究中，通过将核基因组结构与线粒体DNA序列分析相互参照，对两个韩国淡水蚬克隆谱系的遗传结构进行了表征。尽管蚬谱系之间存在显著的遗传差异（内氏遗传距离D = 0.363 - 0.372）以及明显程度的固定等位基因差异（在20个等位酶位点中的6个），但未观察到谱系特异性的线粒体DNA分化。线粒体DNA序列与核基因组之间明显的脱节是存在种间核杂交基因组结构的有力证据，该结构包含父本和母本贡献的不同组合。这一不同寻常的新发现是首个表明在蚬属中存在形态和等位酶上不同但线粒体相同的克隆谱系的案例。然而，在本研究中我们未能找到这两个克隆谱系的祖先物种，这个问题的答案必须等到亚洲蚬类群的遗传结构得到充分表征之后。
