Harr B, Weiss S, David J R, Brem G, Schlötterer C
Institut für Tierzucht und Genetik Josef Baumann Gasse 1, A-1210, Wien, Austria.
Curr Biol. 1998 Oct 22;8(21):1183-6. doi: 10.1016/s0960-9822(07)00490-3.
Uncovering the genealogy of closely related species remains a major challenge for phylogenetic reconstruction. It is unlikely that the phylogeny of a single gene will represent the phylogeny of a species as a whole [1], but DNA sequence data across a large number of loci can be combined in order to obtain a consensus tree [2]. Long sequences are needed, however, to minimize the effect of (infrequent) base substitutions, and sufficient individuals must be sequenced per species to account for intraspecific polymorphisms, an overwhelming task using current DNA sequencing technology. By contrast, microsatellites are easy to type [3], allowing the analysis of many loci in multiple individuals. Despite their successful use in mapping [4,5], behavioural ecology [6] and population genetics [7], their usefulness for the phylogenetic reconstruction of closely related taxa has never been demonstrated, even though microsatellites are often conserved across species [8-10]. One drawback to microsatellite use is their high mutation rate (10(-4)-10(-2)), combined with an incomplete understanding of their mutation patterns. Many microsatellites are available for Drosophila melanogaster, and they are distributed throughout the genome [11]. Most can be amplified in the D. melanogaster species complex [12,13] and have low mutation rates [14, 15]. We show that microsatellite-specific distance measurements [16] correlate with other multilocus distances, such as those obtained from DNA-DNA hybridization data. Thus microsatellites may provide an ideal tool for building multilocus phylogenies. Our phylogenetic reconstruction of the D. melanogaster complex provides strong evidence that D. sechellia arose first, followed by a split between D. simulans and D. mauritiana.
揭示近缘物种的谱系仍然是系统发育重建的一项重大挑战。单个基因的系统发育不太可能代表整个物种的系统发育[1]，但可以整合大量基因座的DNA序列数据以获得一致树[2]。然而，需要长序列来最小化（罕见的）碱基替换的影响，并且每个物种必须对足够数量的个体进行测序以考虑种内多态性，而使用当前的DNA测序技术这是一项艰巨的任务。相比之下，微卫星易于分型[3]，允许对多个个体中的许多基因座进行分析。尽管它们在图谱绘制[4,5]、行为生态学[6]和群体遗传学[7]中得到了成功应用，但它们在近缘分类群系统发育重建中的有用性从未得到证实，尽管微卫星通常在物种间是保守的[8-10]。使用微卫星的一个缺点是它们的高突变率（10^(-4)-10^(-2)），以及对其突变模式的不完全了解。黑腹果蝇有许多微卫星，它们分布在整个基因组中[11]。大多数微卫星可以在黑腹果蝇物种复合体中扩增[12,13]，并且具有低突变率[14,15]。我们表明，微卫星特异性距离测量[16]与其他多位点距离相关，例如从DNA-DNA杂交数据获得的距离。因此，微卫星可能为构建多位点系统发育提供理想工具。我们对黑腹果蝇复合体的系统发育重建提供了有力证据，表明塞舌尔果蝇首先出现，随后是拟暗果蝇和毛里求斯果蝇之间的分化。
