In contrast to the ‘avian-like’ diploid number (2n = 80), most toucans and aracaris (Piciformes: Ramphastidae) have divergent karyotypes, exhibiting a higher 2n. To identify the chromosomal rearrangements that shaped the karyotype of these species, we applied chicken macrochromosome paints 1–10 and 11 microsatellite sequences to the chromosomes of two representative species, Pteroglossus inscriptus and Ramphastos tucannus tucannus. Paints of chicken chromosomes revealed that at least the first five ancestral chromosomes have undergone fissions, and a fusion between a segment of chicken chromosome 1 and a segment from chromosome 3 occurred in both species. The microsatellite sequences were accumulated mainly in the Z chromosome and in several microchromosomes in both species. These results suggest that the genomes of the Ramphastidae have been shaped by extensive fissions and repetitive DNA accumulation as the main driving forces leading to the higher 2n as found in these species. Furthermore, our results suggest that the putative ancestral karyotype of Ramphastidae already had a high diploid number, probably close to 2n = 112, similar to that observed in P. inscriptus and R. t. tucannus.

中文翻译：

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广泛的染色体裂变和重复的DNA积累塑造了两个Ramphastidae（Aves：Piciformes）物种的非典型核型。

与“禽样”二倍体数（2 n = 80）相反，大多数巨嘴鸟和天南星（长形目：Ramphastidae）具有不同的核型，表现出较高的2 n。为了确定影响这些物种核型的染色体重排，我们将鸡大染色体涂料1–10和11微卫星序列应用于两个代表性物种Pteroglossus inscriptus和Ramphastos tucannus tucannus的染色体。鸡染色体的颜料显示至少前五个祖先染色体已经发生了裂变，并且在两个物种中鸡染色体1的一段与染色体3的一段之间都发生了融合。微卫星序列主要聚集在两个物种的Z染色体和几个微染色体中。这些结果表明，Ramphastidae的基因组已被广泛的裂变和重复的DNA积累所塑造，这是导致这些物种中2 n更高的主要驱动力。此外，我们的研究结果表明，假定的兰氏蝇科祖先核型已经具有很高的二倍体数，可能接近2 n = 112，与在P. inscriptus和P. inscriptus中观察到的相似。R.t. 图坎努斯。