Xavier Crislaine, Soares Rógean Vinícius Santos, Amorim Igor Costa, Cabral-de-Mello Diogo Cavalcanti, de Cássia de Moura Rita
Instituto de Ciências Biológicas, Laboratório de Biodiversidade e Genética de Insetos, Universidade de Pernambuco (UPE), Rua Arnóbio Marques 310, Santo Amaro, ZIP: 50.100-130, Recife, PE, Brazil.
Instituto de Biociências, Departamento de Biologia, Universidade Estadual Paulista (UNESP), Rio Claro, SP, Brazil.
Chromosome Res. 2018 Sep;26(3):163-178. doi: 10.1007/s10577-018-9576-1. Epub 2018 Mar 9.
Euchroma Dejean, 1833 (Buprestidae: Coleoptera) is a monotypic genus comprising the species Euchroma gigantea, with populations presenting a degree of karyotypic variation/polymorphism rarely found within a single taxonomic (specific) unit, as well as drastically incompatible meiotic configurations in populations from extremes of the species range. To better understand the complex karyotypic evolution of E. gigantea, the karyotypes of specimens from five populations in Brazil were investigated using molecular cytogenetics and phylogenetic approaches. Herein, we used FISH with histone genes as well as sequencing of the COI to determine differential distribution of markers and relationships among populations. The analyses revealed new karyotypes, with variability for chromosome number and morphology of multiple sex chromosome mechanisms, occurrence of B chromosome variants (punctiform and large ones), and high dispersion of histone genes in different karyotypes. These data indicate that chromosomal polymorphism in E. gigantea is greater than previously reported, and that the species can be a valuable model for cytogenetic studies. The COI phylogenetic and haplotype analyses highlighted the formation of three groups with chromosomally polymorphic individuals. Finally, we compared the different karyotypes and proposed a model for the chromosomal evolution of this species. The species E. gigantea includes at least three cytogenetically polymorphic lineages. Moreover, in each of these lineages, different chromosomal rearrangements have been fixed. Dispersion of repetitive sequences may have favored the high frequency of these rearrangements, which could be related to both adaptation of the species to different habitats and the speciation process.
尤氏吉丁属（Euchroma Dejean，1833年）（吉丁虫科：鞘翅目）是一个单型属，仅包含巨尤氏吉丁（Euchroma gigantea）这一物种。其种群呈现出一定程度的核型变异/多态性，这种情况在单一分类（物种）单元中很少见，而且在该物种分布范围两端的种群中还存在严重不兼容的减数分裂构型。为了更好地理解巨尤氏吉丁复杂的核型进化，我们使用分子细胞遗传学和系统发育方法对巴西五个种群的标本核型进行了研究。在此，我们使用组蛋白基因荧光原位杂交以及细胞色素氧化酶亚基I（COI）测序来确定标记的差异分布以及种群之间的关系。分析揭示了新的核型，包括染色体数目和多种性染色体机制形态的变异性、B染色体变体（点状和大型）的出现以及组蛋白基因在不同核型中的高度分散。这些数据表明，巨尤氏吉丁的染色体多态性比之前报道的更大，并且该物种可以成为细胞遗传学研究的一个有价值的模型。COI系统发育和单倍型分析突出了具有染色体多态性个体的三个组的形成。最后，我们比较了不同的核型，并提出了该物种染色体进化的模型。巨尤氏吉丁物种至少包括三个细胞遗传学多态的谱系。此外，在这些谱系中的每一个中，不同的染色体重排都已固定。重复序列的分散可能有利于这些重排的高频率发生，这可能与该物种对不同栖息地的适应以及物种形成过程都有关。
