Gilbert C, O'Brien P C, Bronner G, Yang F, Hassanin A, Ferguson-Smith M A, Robinson T J
Evolutionary Genomics Group, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
Chromosome Res. 2006;14(8):793-803. doi: 10.1007/s10577-006-1091-0. Epub 2007 Jan 19.
Golden moles (Chrysochloridae) are poorly known subterranean mammals endemic to Southern Africa that are part of the superordinal clade Afrotheria. Using G-banding and chromosome painting we provide a comprehensive comparison of the karyotypes of five species representing five of the nine recognized genera: Amblysomus hottentotus, Chrysochloris asiatica, Chrysospalax trevelyani, Cryptochloris zyli and Eremitalpa granti. The species are karyotypically highly conserved. In total, only four changes were detected among them. Eremitalpa granti has the most derived karyotype with 2n = 26 and differs from the remaining species (all of whom have 2n = 30) by one centric and one telomere:telomere fusion. In addition, two intrachromosomal rearrangements were detected in A. hottentotus. The painting probes also suggest the presence of a unique satellite DNA family located on chromosomes 11 and 12 of both C. asiatica and C. zyli. This represents a synapomorphy linking these two sympatric species as sister taxa. A molecular clock was calibrated adopting a relaxed Bayesian approach for multigene data sets comprising publicly available sequences derived from five gene fragments representative of three golden moles and 39 other eutherian species. The data suggest that golden moles diverged from a common ancestor approximately 28.5 mya (95% credibility interval = 21.5-36.5 mya). Based on an inferred chrysochlorid ancestral karyotype of 2n = 30, the estimated rate of 0.7 rearrangements per 10 my (95% Credibility Interval = 0.54-0.93) differs from the 'default rate' of mammalian chromosomal evolution which has been estimated at one change per 10 million years, thus placing the Chrysochloridae among the slower-evolving chromosomal lineages thus far recorded.
金毛鼹科动物是非洲南部特有的鲜为人知的地下哺乳动物，属于非洲兽总目进化枝。我们使用G带和染色体涂染技术，对代表9个公认属中5个属的5个物种的核型进行了全面比较，这5个物种分别是霍屯督金毛鼹、亚洲金毛鼹、开普金毛鼹、齐氏金毛鼹和格兰特金毛鼹。这些物种在核型上高度保守。总共仅检测到4处变化。格兰特金毛鼹的核型最为衍生，2n = 26，与其余物种（均为2n = 30）的差异在于一次着丝粒融合和一次端粒：端粒融合。此外，在霍屯督金毛鼹中检测到两次染色体内重排。涂染探针还表明，在亚洲金毛鼹和齐氏金毛鼹的11号和12号染色体上存在一个独特的卫星DNA家族。这代表了一种共衍征，将这两个同域物种联系为姐妹类群。采用宽松贝叶斯方法，对包含来自3种金毛鼹和39种其他真兽类物种的5个基因片段的公开可用序列的多基因数据集进行分子钟校准。数据表明，金毛鼹大约在2850万年前从一个共同祖先分化而来（95%可信区间 = 2150 - 3650万年前）。基于推断的金毛鼹科祖先核型2n = 30，估计每1000万年有0.7次重排（95%可信区间 = 0.54 - 0.93），这与哺乳动物染色体进化的“默认速率”（估计为每1000万年一次变化）不同，因此将金毛鼹科置于迄今为止记录的进化较慢的染色体谱系之中。
