Pavlova Svetlana V, Borisov Sergei A, Timoshenko Alexander F, Sheftel Boris I
A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky pr., 119071 Moscow, Russia.
Irkutsk Antiplague Research Institute of Rospotrebnadzor, 78 Trilissera str., 664047 Irkutsk, Russia.
Comp Cytogenet. 2017 Nov 24;11(4):797-806. doi: 10.3897/CompCytogen.v11i4.19800. eCollection 2017.
Karyotype studies of common shrews in the vicinity of Lake Baikal (Irkutsk Region, Eastern Siberia) resulted in the description of two new chromosomal races of Linnaeus, 1758 (Lypotyphla, Mammalia), additional to 5 races formerly found in Siberia. In the karyotypes of 12 specimens from 3 locations, the polymorphism of metacentric and acrocentric chromosomes of the Robertsonian type was recorded and two distinct groups of karyotypes interpreted as the chromosomal races were revealed. They are geographically distant and described under the racial names Irkutsk (Ir) and Zima (Zi). Karyotypes of both races were characterized by species-specific (the same for all 74 races known so far) metacentric autosomes and , and the typical sex chromosome system - XX/XYY. The race-specific arm chromosome combinations include three metacentrics and four acrocentrics in the Irkutsk race () and four metacentrics and two acrocentrics in the Zima race (). Within the races, individuals with polymorphic chromosomes were detected (). The presence of the specific metacentric allowed us to include the Irkutsk race into the Siberian Karyotypic Group (SKG), distributed in surrounding regions. The Zima race karyotype contained two metacentrics, and , which have been never found in the Siberian part of the species range, but appear as the common feature of chromosomal races belonging to the West European Karyotypic Group (WEKG). Moreover, the metacentrics of that karyotype are almost identical to the Åkarp race (except the heterozygous pair ) locally found in the southern Sweden. One of two Siberian races described here for the first time, the Zima race, occurs in an area considerably distant from Europe and shares the common metacentrics () with races included in WEKG. This fact may support a hypothesis of independent formation of identical arm chromosome combinations due to occurrence of the same centric fusions in different parts of the species range.
对贝加尔湖附近（东西伯利亚伊尔库茨克地区）普通鼩鼱的核型研究，除了先前在西伯利亚发现的5个种群外，还描述了1758年林奈所命名的两个新的染色体族（真盲缺目，哺乳纲）。在来自3个地点的12个标本的核型中，记录了罗伯逊氏型中着丝粒染色体和近端着丝粒染色体的多态性，并揭示了两组不同的核型，被解释为染色体族。它们在地理上相距遥远，并分别以伊尔库茨克（Ir）和济马（Zi）这两个族名来描述。两个族的核型都具有物种特异性（到目前为止已知的所有74个族都是如此）的中着丝粒常染色体 和 ，以及典型的性染色体系统——XX/XYY。族特异性的臂染色体组合在伊尔库茨克族（ ）中有三条中着丝粒染色体和四条近端着丝粒染色体，在济马族（ ）中有四条中着丝粒染色体和两条近端着丝粒染色体。在各族内，检测到了具有多态染色体的个体（ ）。特定中着丝粒染色体 的存在使我们能够将伊尔库茨克族归入分布在周边地区的西伯利亚核型群（SKG）。济马族的核型包含两条中着丝粒染色体 和 ，在该物种分布范围的西伯利亚部分从未发现过，但却是属于西欧核型群（WEKG）的染色体族的共同特征。此外，该核型的中着丝粒染色体几乎与瑞典南部当地发现的阿卡普族（除了杂合对 ）相同。这里首次描述的两个西伯利亚族之一，济马族，出现在一个距离欧洲相当远的地区，并且与WEKG中的族共享共同的中着丝粒染色体（ ）。这一事实可能支持这样一种假设，即由于在物种分布范围的不同部分发生了相同的着丝粒融合，导致相同的臂染色体组合独立形成。
