Maeda Kaoru, Takeda Miyuki, Kamiya Koichi, Aibara Mitsuto, Mzighani Semvua Isa, Nishida Mutsumi, Mizoiri Shinji, Sato Tetsu, Terai Yohey, Okada Norihiro, Tachida Hidenori
Department of Biology, Faculty of Sciences, Kyushu University, Ropponmatsu, Fukuoka 810-8560, Japan.
Gene. 2009 Jul 15;441(1-2):67-73. doi: 10.1016/j.gene.2008.11.008. Epub 2008 Nov 21.
Cichlid fishes in Lake Victoria show spectacular diversification that is thought to be recent. Therefore, by investigating those fishes, we may be able to elucidate recently completed or ongoing speciation processes. We studied the population structures of two closely related pelagic cichlid species, Haplochromis pyrrhocephalus and H. laparogramma, using a mitochondrial DNA locus and 12 nuclear microsatellite loci as putative neutral markers. Ten and two populations of H. pyrrhocephalus and H. laparogramma, respectively, were sampled from the southern part of Lake Victoria. We grouped those 12 populations into four mutually differentiated regional populations, one of which consisted of the two H. laparogramma populations. The levels of differentiation were substantial at the mitochondrial locus (F(ST) = 0.03-0.54), but very low at microsatellite loci (R(ST) = 0.008-0.116). The data from both types of loci indicated that the regional population of H. laparogramma was first separated from those of H. pyrrhocephalus if we set aside one erratic population of H. pyrrhocephalus. The data also suggested recent population expansions of the two species, the time scales for which were estimated to be on the order of 10(4)-10(5) years. These data suggested that dynamic speciation processes accompanied occasional spawning of new species and population size changes in this lake.
维多利亚湖中的丽鱼科鱼类呈现出惊人的多样化，这种多样化被认为是近期发生的。因此，通过研究这些鱼类，我们或许能够阐明近期完成或正在进行的物种形成过程。我们使用线粒体DNA位点和12个核微卫星位点作为假定的中性标记，研究了两种亲缘关系密切的浮游丽鱼科物种——红顶朴丽鱼（Haplochromis pyrrhocephalus）和腹纹朴丽鱼（H. laparogramma）的种群结构。分别从维多利亚湖南部采集了10个红顶朴丽鱼种群和2个腹纹朴丽鱼种群。我们将这12个种群分为4个相互有差异的区域种群，其中一个区域种群由2个腹纹朴丽鱼种群组成。在线粒体位点上，分化水平较高（F(ST) = 0.03 - 0.54），但在微卫星位点上分化水平非常低（R(ST) = 0.008 - 0.116）。如果我们不考虑红顶朴丽鱼的一个不稳定种群，来自这两种位点的数据都表明腹纹朴丽鱼的区域种群首先与红顶朴丽鱼的区域种群分离。数据还表明这两个物种近期出现了种群扩张，估计时间尺度在10(4) - 10(5)年的量级。这些数据表明，在这个湖泊中，动态的物种形成过程伴随着新物种的偶尔产生和种群大小的变化。
