Warchałowska-Śliwa Elżbieta, Grzywacz Beata, Maryańska-Nadachowska Anna, Heller Klaus-Gerhard, Hemp Claudia
Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016 Kraków, Poland Polish Academy of Sciences Kraków Poland.
Magdeburg, Germany Unaffiliated Magdeburg Germany.
Comp Cytogenet. 2020 Aug 28;14(3):417-435. doi: 10.3897/CompCytogen.v14i3.54422. eCollection 2020.
Hemp, 2016 is one of the most widespread bush-crickets of the genus Karsch, 1889 in East Africa. This species with seven large chromosomes (2n♂ = 7) differs from other representatives of the genus drastically by its reduced chromosome number, the asymmetrical karyotype including karyomorphs rarely found in tettigoniids, as well as in irregularities in the course of meiosis. To better understand the origin of such an exceptional karyotype, chromosomes of 29 specimens from four populations/localities were studied using classical techniques, such as C-banding, silver impregnation, fluorochrome double staining and fluorescence hybridization (FISH) technique with 18S rDNA and (TTAGG) telomeric probes. FISH showed many 18S rDNA loci as well as interstitial telomeric sequences, where chromosome morphology varied in these components in terms of quantity and distribution. The 18S rDNA loci coincided with active NORs and C-banding patterns. We suggest that a combination of Robertsonian rearrangements and/or multiple common tandem fusions involving the same chromosomes contributed to the formation of this karyotype/karyomorphs. The results are the first step towards a better understanding of chromosomal reorganization and evolution within the genus . Low chromosome number, together with the incidence of chromosomal polymorphism that is higher in than previously reported in bush-crickets, implies that this species can be a valuable new model for cytogenetic and speciation studies. Our findings suggest that chromosomal translocations lead to diversification and speciation in this species and could be the driving force of adaptive radiation.
大麻蝗（Hemp, 2016）是1889年卡尔施属（Karsch）在东非分布最广的螽斯之一。该物种有七条大染色体（2n♂ = 7），其染色体数目减少、核型不对称（包括在螽斯中很少见的核型变体）以及减数分裂过程中的不规则性，使其与该属的其他代表物种有很大不同。为了更好地理解这种特殊核型的起源，我们使用经典技术，如C带染色、银染、荧光染料双重染色以及用18S rDNA和（TTAGG）端粒探针进行荧光杂交（FISH）技术，研究了来自四个种群/地点的29个标本的染色体。FISH显示出许多18S rDNA位点以及居间端粒序列，在这些成分中，染色体形态在数量和分布方面有所不同。18S rDNA位点与活跃的核仁组织区（NORs）和C带模式一致。我们认为，罗伯逊重排和/或涉及相同染色体的多个常见串联融合的组合促成了这种核型/核型变体的形成。这些结果是朝着更好地理解该属内染色体重组和进化迈出的第一步。低染色体数目，以及该物种中染色体多态性的发生率高于此前报道的螽斯，这意味着该物种可能是细胞遗传学和物种形成研究的一个有价值的新模型。我们的研究结果表明，染色体易位导致了该物种的多样化和物种形成，可能是适应性辐射的驱动力。
