Molina Wagner Franco, Martinez Pablo A, Bertollo Luiz Antônio C, Bidau Claudio Juan
Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, 59078-970 Natal, RN, Brazil.
Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís, Km 235, 13565-905 São Carlos, SP, Brazil.
Mar Genomics. 2014 Jun;15:29-34. doi: 10.1016/j.margen.2014.05.001. Epub 2014 May 17.
The process of preferential chromosome segregation during meiosis has been suggested to be responsible for the predominance of certain chromosome types in the karyotypes of mammals, birds and insects. We developed an extensive analysis of the fixation of mono- or bibrachial chromosomes in the karyotypes of the large Actinopterygii fish group, a key link in the evolution of terrestrial vertebrates, in order to investigate the generality of meiotic drive in determining karyotypic macrotrends. Unlike mammals, fishes have markedly undergone several types of preferential chromosomal rearrangements throughout evolution. Data from the analyzed orders indicate a prevalence of karyotypes with few (<33%) or many (>66%) acrocentric chromosomes and a low number of karyotypes with balanced numbers of mono- and bi-brachial elements. Parallel trends towards a higher number of karyotypes with prevalence of monobrachial chromosomes occurred in phylogenetically close orders (e.g. Perciformes and Tetraodontiformes, and in the order Mugiliformes) and in clades with prevalence of bibrachial elements (e.g. Characiformes, Gymnotiformes, Siluriformes, and Cypriniformes). Some orders where fewer species were available for study, such as Atheriniformes and Anguilliformes, showed karyotype assemblages where both trends were present. Our results strongly suggest a primary role of meiotic drive in karyotypic evolution as indicated by the accumulation of monobrachial chromosomes in Perciformes and Cypriniformes, or bibrachial chromosomes in Siluriformes and Characiformes. Further examinations of the interaction between life history traits, environmental characteristics, and the fixation of chromosomal rearrangements would be exceedingly valuable.
减数分裂过程中染色体的优先分离被认为是哺乳动物、鸟类和昆虫核型中某些染色体类型占优势的原因。我们对大型辐鳍鱼纲鱼类群体的核型中单臂或双臂染色体的固定情况进行了广泛分析，该鱼类群体是陆地脊椎动物进化的关键环节，目的是研究减数分裂驱动在决定核型宏观趋势方面的普遍性。与哺乳动物不同，鱼类在整个进化过程中明显经历了几种类型的优先染色体重排。分析的目的数据表明，核型中具有少数（<33%）或多数（>66%）近端着丝粒染色体的情况较为普遍，而具有平衡数量的单臂和双臂元件的核型数量较少。在系统发育关系密切的目（如鲈形目和鲀形目，以及鲻形目）和以双臂元件为主的类群（如脂鲤目、电鳗目、鲇形目和鲤形目）中，出现了单臂染色体占优势的核型数量增加的平行趋势。一些可供研究的物种较少的目，如银汉鱼目和鳗鲡目，其核型组合显示出两种趋势都存在。我们的结果强烈表明，减数分裂驱动在核型进化中起主要作用，如鲈形目和鲤形目中单臂染色体的积累，或鲇形目和脂鲤目中双臂染色体的积累所示。进一步研究生活史特征、环境特征与染色体重排固定之间的相互作用将非常有价值。
