Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.
PLoS One. 2013 Sep 6;8(9):e74088. doi: 10.1371/journal.pone.0074088. eCollection 2013.
The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate how this structure relates to the ecological conditions that caused their adaptation. We analyzed the genetic structure of two pelagic and seven littoral species sampled from the southeast area of Lake Victoria using sequences from the mtDNA control region and 12 microsatellite loci as markers. Using a Bayesian model-based clustering method to analyze the microsatellite data, we separated these nine species into four groups: one group composed of pelagic species and another three groups composed mainly of rocky-shore species. Furthermore, we found significant levels of genetic variation between species within each group at both marker loci using analysis of molecular variance (AMOVA), although the nine species often shared mtDNA haplotypes. We also found significant levels of genetic variation between populations within species. These results suggest that initial groupings, some of which appear to have been related to habitat differences, as well as divergence between species within groups took place among the cichlid species of Lake Victoria.
东非维多利亚湖中的大约 700 种丽鱼科鱼类被认为是在短时间内进化而来的，它们代表了已知的最大的适应性辐射之一。为了了解驱动这种壮观辐射的过程，我们必须确定这些物种的当前遗传结构，并阐明这种结构与导致它们适应的生态条件有何关系。我们使用来自 mtDNA 控制区和 12 个微卫星位点的序列分析了从维多利亚湖南部地区采集的两种浮游和七种滨岸物种的遗传结构。使用基于贝叶斯模型的聚类方法分析微卫星数据，我们将这 9 种物种分为 4 组：一组由浮游物种组成，另外 3 组主要由岩石海岸物种组成。此外，我们在每个标记基因座上使用分子方差分析（AMOVA）发现了组内种间显著的遗传变异水平，尽管 9 种物种经常共享 mtDNA 单倍型。我们还发现了种内种群之间显著的遗传变异水平。这些结果表明，丽鱼科物种在维多利亚湖的最初分组中，有些似乎与栖息地差异有关，以及组内物种之间的分歧已经发生。
