Laboratório de Citogenética de Insetos, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Laboratório de Citogenética e Citometria, Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Insect Mol Biol. 2021 Aug;30(4):379-389. doi: 10.1111/imb.12702. Epub 2021 Apr 14.
Genome changes, evidenced through karyotype or nuclear genome size data, can result in reproductive isolation, diversification and speciation. The aim of this study was to understand how changes in the karyotype such as chromosome number and nuclear genome size accompanied the evolution of neotropical stingless bees, and to discuss these data in a phylogenetic context focusing on the karyotype evolution of this clade. We sampled 38 species representing the three Neotropical Meliponini groups; 35 for karyotype analyses and 16 for 1C value measurement. The chromosome number varied from 2n = 16 to 2n = 34, with distinct karyotypic formulae and the presence of a few polymorphisms, such as B chromosomes in one species and arm size differences between homologous chromosomes in two species. The mean 1C value varied from 0.31 pg to 0.92 pg. We associated empirical data on chromosome number and mean 1C value to highlight the importance of Robertsonian fusion rearrangements, leading to a decrease in chromosome number during the Neotropical Meliponini evolution. These data also allowed us to infer the independent heterochromatin amplification in several genera. Although less frequent, Melipona species with 2n = 22 represent evidence of Robertsonian fissions. We also pointed out the importance of chromosomal rearrangements that did not alter chromosome number, such as inversions and heterochromatin amplification.
基因组变化，通过核型或核基因组大小数据得到证明，可以导致生殖隔离、多样化和物种形成。本研究的目的是了解染色体数和核基因组大小等染色体变化如何伴随着新热带无刺蜂的进化，并在关注该进化枝的核型进化的系统发育背景下讨论这些数据。我们采样了 38 个代表新热带 Meliponini 三个组的物种；35 个用于核型分析，16 个用于 1C 值测量。染色体数从 2n=16 到 2n=34 不等，具有明显的核型公式和一些多态性，如一个物种中的 B 染色体和两个物种中同源染色体臂大小的差异。平均 1C 值从 0.31 pg 到 0.92 pg 不等。我们将染色体数和平均 1C 值的经验数据联系起来，以强调罗伯逊易位融合在新热带 Meliponini 进化过程中导致染色体数减少的重要性。这些数据还使我们能够推断出几个属中的独立异染色质扩增。虽然不太常见，但具有 2n=22 的 Melipona 物种代表了罗伯逊分裂的证据。我们还指出了染色体重排的重要性，这些重排没有改变染色体数，如倒位和异染色质扩增。
