Chilton Neil B, Huby-Chilton Florence, Smales Lesley R, Gasser Robin B, Beveridge Ian
Department of Veterinary Science, The University of Melbourne, Werribee, 3030 Victoria, Australia.
Parasitol Res. 2009 Jan;104(2):229-36. doi: 10.1007/s00436-008-1178-y. Epub 2008 Sep 16.
Sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal (r) DNA were characterised for Labiosimplex australis, a parasitic nematode of macropodid marsupials from continental Australia and from island populations which have been isolated from mainland Australia for relatively short periods of time (<40,000 years). The results showed that the geographically isolated populations of L. australis on Kangaroo Island and Tasmania were genetically different from each other and from populations on the mainland. There were two unequivocal nucleotide differences sites within the ITS-1 rDNA sequence between the two island populations; however, the ITS-1 sequences of individuals from mainland populations contained one or both of these nucleotides. In contrast, L. australis from each island population had unique nucleotides in ITS-2 sequence that were not detected in any individual from the mainland. Although these results are consistent with the hypothesis that L. australis represents a single species, the genetic divergence in the ITS-2 sequences amongst individuals from different isolated populations suggests that the island populations of L. australis may be in the initial stages of allopatric speciation.
对澳大利亚唇形线虫（Labiosimplex australis）核糖体（r）DNA的第一和第二内部转录间隔区（ITS-1和ITS-2）序列进行了特征分析。澳大利亚唇形线虫是一种寄生于澳大利亚大陆有袋目有袋动物以及与澳大利亚大陆隔离时间相对较短（<40,000年）的岛屿种群的寄生线虫。结果表明，袋鼠岛和塔斯马尼亚岛上地理隔离的澳大利亚唇形线虫种群在基因上彼此不同，且与大陆种群也不同。两个岛屿种群的ITS-1 rDNA序列中有两个明确的核苷酸差异位点；然而，大陆种群个体的ITS-1序列包含这两个核苷酸中的一个或两个。相比之下，每个岛屿种群的澳大利亚唇形线虫在ITS-2序列中有独特的核苷酸，而在大陆的任何个体中均未检测到。尽管这些结果与澳大利亚唇形线虫代表单一物种的假设一致，但来自不同隔离种群个体的ITS-2序列中的遗传差异表明，澳大利亚唇形线虫的岛屿种群可能正处于异域物种形成的初始阶段。
