Speciation, karyotypic differentiation, and hybrid zones in the Gagrellula ferruginea-group (Arachnida, Opiliones)

由三种（g.f arruginea, g.g grandis, g.p .）组成的Gagrellula ferruginea类群在种间和种内均表现出很大的核型变异。研究了该类群核型分化的地理格局和染色体杂交带在物种形成过程中的作用。主要结果如下：(1)G.ferruginea的染色体数为2n=10 ~ 24， G.sp的染色体数为2n=18 ~ 20。在G.grandis中2n=20。其中，G.ferruginea在组内分布最广，在核型和外部形态上变异最大。基本上，核型的分化与外部形态之间没有密切的联系。(2)本州县北部探戈山周边地区的铁豆属植物染色体数量多样性最大；其中取值范围为2n=14 ~ 20。在两个染色体数目不同的群体相邻的每一点上，总能找到一个杂交带。(3)“Gagrellula ferruginea”的两个地理种族（九州-广岛种族和雏菊种族）在广岛市西部相遇，其活动范围略有重叠。在重叠区，两种狗的腿身相对长度差异显著；指示字符移位的发生。(4)发现染色体数目不同的两个地理种群均存在或多或少的前合子生殖隔离，但通常不完全，从而形成杂交带。

The Gagrellula ferruginea-group, consisting of three species (G.ferruginea, G.grandis, G.sp.), shows great karyotypic variability both between and within species. Geographical patterns of the karyotype differentiation and the role of the chromosomal hybrid zones in the speciation process of the group were investigated. The principal results obtained are as follows : (1) The number of chromosomes ranged from 2n=10 to 24 in G.ferruginea, 2n=18-20 in G.sp. and 2n=20 in G.grandis. Of these, G.ferruginea, occupying the widest ranges in the group, was most variable in both karyotypes and external morphology. Basically, no close association was found between differentiations in karyotypes and external morphology. (2) G.ferruginea showed greatest diversity in chromosome number in the area surrounding Tango Mountains in northern Kink district, Honshu ; where the number ranges from 2n=14 to 20. At the every points where two populations with different chromosome numbers abut, a hybrid zone was always found. (3) Two geographic races (Kyushu-Hiroshima race and Daises race) of "Gagrellula ferruginea" meet in the western of Hiroshima Prefecture, with a slight overlap of their ranges. In the overlap zone, relative length of legs to body significantly differed between the two races ; indicating occurrence of character displacement. (4) It was found that two geographical populations with different chromosome numbers show prezygotic reproductive isolation more or less, though it is usually far from complete and hence hybrid zones are formed.