Myiopsitta monachus is a small Neotropical parrot (Psittaciformes: Arini Tribe) from subtropical and temperate regions of South America. It has a diploid chromosome number 2n = 48, different from other members of the Arini Tribe that have usually 70 chromosomes. The species has the lowest 2n within the Arini Tribe. In this study, we combined comparative chromosome painting with probes generated from chromosomes of Gallus gallus and Leucopternis albicollis, and FISH with bacterial artificial chromosomes (BACs) selected from the genome library of G. gallus with the aim to shed light on the dynamics of genome reorganization in M. monachus in the phylogenetic context. The homology maps showed a great number of fissions in macrochromosomes, and many fusions between microchromosomes and fragments of macrochromosomes. Our phylogenetic analysis by Maximum Parsimony agree with molecular data, placing M. monachus in a basal position within the Arini Tribe, together with Amazona aestiva (short tailed species). In M. monachus many chromosome rearrangements were found to represent autopomorphic characters, indicating that after this species split as an independent branch, an intensive karyotype reorganization took place. In addition, our results show that M. monachus probes generated by flow cytometry provide novel cytogenetic tools for the detection of avian chromosome rearrangements, since this species presents breakpoints that have not been described in other species.

鲇鱼是一种来自南美洲亚热带和温带地区的小型新热带鹦鹉（鹦鹉形目：Arini 部落）。它有一个二倍体染色体编号 2n= 48，与通常有 70 条染色体的 Arini 部落的其他成员不同。该物种最低2n在阿里尼部落内。在这项研究中，我们将比较染色体绘制与从染色体产生的探针相结合。鸡鸡和白蛉, 和 FISH 与从基因组库中选择的细菌人工染色体 (BAC)G.鸡旨在阐明基因组重组的动力学M. monachus在系统发育背景下。同源图显示大染色体中存在大量裂变，小染色体与大染色体片段之间存在大量融合。我们通过Maximum Parsimony进行的系统发育分析与分子数据一致，将米.独角兽在阿里尼部落中处于基础地位，与亚马逊河（短尾物种）。在M. monachus发现许多染色体重排代表自体特征，表明在该物种作为独立分支分裂后，发生了密集的核型重组。此外，我们的结果表明，米.独角兽流式细胞仪产生的探针为检测禽类染色体重排提供了新的细胞遗传学工具，因为该物种存在其他物种未描述的断点。