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.

中文翻译：

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深入了解甲虫Euchroma gigantea（鞘翅目：Buprestidae）的核型进化和物种形成。

Euchroma Dejean，1833（Buprestidae：Coleoptera）是由Euchroma gigantea物种组成的单型属，其种群呈现出一定程度的核型变异/多态性，在单个分类学（特定）单位中很少见，并且该种群的减数分裂构型严重不兼容物种范围的极端。为了更好地了解巨型大肠埃希氏菌的复杂核型演化，使用分子细胞遗传学和系统发育方法研究了来自巴西五个种群的标本的核型。在本文中，我们将FISH与组蛋白基因一起使用，并对COI进行测序，以确定标记的差异分布以及人群之间的关系。分析揭示了新的核型，其染色体数目和多种性染色体机制的形态具有变异性，B染色体变异（点状和大号）的发生，以及组蛋白基因在不同核型中的高度分散。这些数据表明，大肠埃希氏菌中的染色体多态性比以前报道的要大，并且该物种可能是细胞遗传学研究的有价值的模型。COI系统发育和单倍型分析突出显示了三组具有染色体多态性的个体。最后，我们比较了不同的核型，并提出了该物种的染色体进化模型。巨型埃希氏菌物种包括至少三个细胞遗传多态谱系。此外，在这些谱系的每一个中，已固定了不同的染色体重排。重复序列的分散可能有利于这些重排的高频率，