Vargo Edward L, Husseneder Claudia, Grace J Kenneth
Department of Entomology, Box 7613, North Carolina State University, Raleigh, NC 27695-7613, USA.
Mol Ecol. 2003 Oct;12(10):2599-608. doi: 10.1046/j.1365-294x.2003.01938.x.
Subterranean termites have unusual plasticity in their breeding systems. As a result of their cryptic foraging and nesting habits, detailed information on the numbers and types of reproductive individuals in colonies has been difficult to obtain. In this study, we used microsatellite markers to infer the major features of the breeding system of the Formosan subterranean termite, Coptotermes formosanus, in southern Japan, where it is believed to have been introduced from China. A total of 30 colonies was sampled from two islands (Kyushu and Fukue) located 100 km apart. Twenty workers from each colony were genotyped at six microsatellite loci. Analysis of worker genotypes within colonies indicated that 27 colonies (90%) were simple (Mendelian) families. The remaining three colonies, all from Kyushu, were consistent with being extended families having begun as simple families but being currently headed by multiple neotenic (secondary) reproductives descended from the original king and queen. Workers from simple families in both populations were significantly inbred (FIT = 0.10 for Kyushu and 0.46 for Fukue) and highly related to their nestmates (coefficient of relatedness, r = 0.59 for Kyushu and 0.77 for Fukue), suggesting that many simple-family colonies were headed by closely related reproductives, especially in the Fukue population. This conclusion is supported by the high coefficient of relatedness between nestmate reproductives in simple-family colonies (r = 0.23 for Kyushu and 0.61 for Fukue) based on genotypes inferred from their worker offspring. There was moderate genetic differentiation (FST = 0.12) between the two populations, suggesting rather restricted gene flow between them. There was no significant isolation by distance among colonies, as might be expected given the limited dispersal of reproductives, presumably because of the frequent movement of colonies by humans. Finally, there was no evidence of a recent bottleneck, a finding possibly consistent with the more than 300-year history of this species in Japan.
地下白蚁的繁殖系统具有不同寻常的可塑性。由于它们隐秘的觅食和筑巢习性，很难获得关于蚁群中生殖个体数量和类型的详细信息。在本研究中，我们使用微卫星标记来推断台湾乳白蚁（Coptotermes formosanus）在日本南部繁殖系统的主要特征，据信该物种是从中国引入日本的。从相距100公里的两个岛屿（九州岛和福江岛）共采集了30个蚁群。对每个蚁群的20只工蚁在6个微卫星位点进行基因分型。对蚁群内工蚁基因型的分析表明，27个蚁群（90%）为简单（孟德尔式）家族。其余3个蚁群均来自九州岛，符合扩展家族的特征，这些家族最初是简单家族，但目前由源自原始蚁王和蚁后的多个若蚁（次级）生殖个体领导。两个种群中简单家族的工蚁都存在显著的近亲繁殖现象（九州岛的FIT = 0.10，福江岛的FIT = 0.46），并且与同巢伙伴的亲缘关系很高（亲缘系数，九州岛的r = 0.59，福江岛的r = 0.77），这表明许多简单家族蚁群由亲缘关系密切的生殖个体领导，尤其是在福江岛种群中。基于从其工蚁后代推断出的基因型，简单家族蚁群中同巢生殖个体之间的高亲缘系数（九州岛的r = 0.23，福江岛的r = 0.61）支持了这一结论。两个种群之间存在中等程度的遗传分化（FST = 0.12），表明它们之间的基因流动相当有限。正如预期的那样，考虑到生殖个体的扩散有限，蚁群之间没有显著的距离隔离，这可能是因为人类频繁移动蚁群。最后，没有证据表明近期存在瓶颈效应，这一发现可能与该物种在日本超过300年的历史相一致。
