Ferreira Milena, de Jesus Isac S, Viana Patrik F, Garcia Caroline, Matoso Daniele A, Cioffi Marcelo B, Bertollo Luiz A C, Feldberg Eliana
Laboratório de Genética Animal, Programa de Pó-graduação em Genética, Conservação e Biologia Evolutiva, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil.
Secretaria de Estado de Educação e Qualidade do Ensino (SEDUC), Manaus, Brazil.
Cytogenet Genome Res. 2020;160(9):539-553. doi: 10.1159/000511125. Epub 2020 Nov 23.
The family Aspredinidae comprises a clade of complex systematic relationships, both from molecular and morphological approaches. In this study, conventional and molecular cytogenetic studies coupled with nucleotide sequencing were performed in 6 Aspredininae species (Amaralia hypsiura, Bunocephalus cf. aloikae, Bunocephalus amaurus, Bunocephalus aff. coracoideus, Bunocephalus verrucosus, and Platystacus cotylephorus) from different locations of the Amazon hydrographic basin. Our results showed highly divergent diploid numbers (2n) among the species, ranging from 49 to 74, including the occurrence of an XX/X0 sex chromosome system. A neighbor-joining phylogram based on the cytochrome c oxidase I (COI) showed that Bunocephalus coracoideus is not a monophyletic clade, but closely related to B. verrucosus. The karyotypic data associated with COI suggest an ancestral karyotype for Aspredinidae with a reduced 2n, composed of bi-armed chromosomes and a trend toward chromosomal fissions resulting in higher diploid number karyotypes, mainly composed of acrocentric chromosomes. Evolutionary relationships were discussed under a phylogenetic context with related species from different Siluriformes families. The karyotype features and chromosomal diversity of Aspredinidae show an amazing differentiation, making this family a remarkable model for investigating the evolutionary dynamics in siluriforms as well as in fish as a whole.
拟鲿科是一个系统关系复杂的进化枝，这一点从分子学和形态学研究方法中均能体现。在本研究中，我们对来自亚马孙水系不同地点的6种拟鲿亚科鱼类（高背拟鲿、阿氏牛头鲿、黑牛头鲿、似喙牛头鲿、瘤牛头鲿和平头鲿）进行了传统细胞遗传学和分子细胞遗传学研究，并结合了核苷酸测序。我们的结果显示，这些物种的二倍体数目（2n）差异很大，范围从49到74，其中还出现了XX/X0性染色体系统。基于细胞色素c氧化酶I（COI）构建的邻接系统发育树表明，喙状牛头鲿并非单系进化枝，而是与瘤牛头鲿关系密切。与COI相关的核型数据表明，拟鲿科的祖先核型具有较低的2n，由双臂染色体组成，并且存在染色体断裂的趋势，从而导致具有较高二倍体数目的核型，主要由近端着丝粒染色体组成。我们在系统发育背景下讨论了与不同鲇形目科的相关物种的进化关系。拟鲿科的核型特征和染色体多样性显示出惊人的分化，使其成为研究鲇形目以及整个鱼类进化动态的一个显著模型。
