Phylogenetic studies of pantherine cats (Felidae) based on multiple genes, with novel application of nuclear beta-fibrinogen intron 7 to carnivores

The pantherine lineage of the cat family Felidae (order: Carnivora) includes five big cats of genus Panthera and a great many midsized cats known worldwide. Presumably because of their recent and rapid radiation, the evolutionary relationship among pantherines remains ambiguous. We provide an independent assessment of the evolutionary history of pantherine lineage using two complete mitochondrial (mt) genes (ND2 and ND4) and the nuclear beta-fibrmogen intron 7 gene, whose utility in carnivoran phylogeny was first explored. The available four mt (ND5, cytb, 12S, and 16SrRNA) and two nuclear (IRBP and TTR) sequence loci were also combined to reconstruct phylogeny of 14 closely related cat species. Our analyses of combined mt data (six genes; approximate to 3750 bp) and combined mt and nuclear data (nine genes; approximate to 6500 bp) obtained identical tree topologies, which were well-resolved and strongly supported for almost all nodes. Monophyly of Panthera genus in pantherine lineage was confirmed and interspecific affinities within this genus revealed a novel branching pattern, with P. tigris diverging first in Panthera genus, followed by P. onca, P. leo, and last two sister species P. pardus and P. uncia. In addition, close association of Neofelis nebulosa to Panthera, the phylogenetic redefinition of Otocolobus manil within the domestic cat group, and the relatedness of Acinonyx jubatus and Puma concolor were all important findings in the resulting phylogenies. The potential utilities of nine different genes for phylogenetic resolution of closely related pantherine species were also evaluated, with special interest in that of the novel nuclear beta-fibrinogen intron 7. (c) 2005 Elsevier Inc. All rights reserved.

食肉动物的比较分子细胞遗传学研究

猫和狗是人类重要的伴侣动物，也是生物医学研究的重要模式动物。猫是哺乳动物中核型最为保守的物种之一，而狗的基因组则经历了迄今为止最为广泛的重组。猫和狗基因组计划的长足进步，使猫和狗的基因组成为食肉动物比较基因组研究理想的参照物。种间染色体涂色，以其准确、高效和适合于全基因组比较等优点，已成为比较细胞遗传学，特别是远缘物种或核型高度重排物种间比较的首选方法。利用染色体涂色技术建立的比较染色体图谱，记录了物种形成过程中所发生的基因组改变的历史。通过比较分析保守的染色体片段在不同系统发生分支物种上的分布和排列方式，可以推测在被比较物种之间，染色体重排的速率、类型和方向以及系统发生关系，重建哺乳动物的基因组进化历程。本研究利用人、狗、猫和石貂的染色体特异探针，通过染色体涂色，建立了人与石貂以及食肉动物各主要类群物种间的比较染色体图谱。研究结果表明，现生的食肉动物可以被分成三组，每一组具有其独特的祖先核型组成、染色体改变的速率和进化途径等特征。，第一组由具有高度保守核型的猫超科、融科、洗熊科和小熊猫等组成。第二组是大熊猫和熊科，具有中等程度的核型重排。第三组是犬科，具有高度重排的核型。猫和石貂等核型保守物种的探针有利于检测染色体间的重排，而基因组高度重排的狗染色体探针则有利于追踪核型保守的物种在基因组进化过程中发生的染色体内重排，为探讨食肉动物的核型进化提供了进一步的信息。另外，我们的结果还表明小熊猫与融科动物之间有很近的系统发生关系。根据这些比较染色体图谱，重建了食肉动物各主要系统发生分支的祖先核型和核型系统发生关系。这些比较染色体图谱的建立有助于理解食肉动物基因组进化和系统发生关系，促进人、猫和狗的基因序列数据和定位资料向其他没有基因定位数据的食肉动物转移。