Ozeki Masato, Isagi Yuji, Tsubota Hiromi, Jacklyn Peter, Bowman David M J S
Graduate School for International Development and Cooperation, Hiroshima University, Kagamiyama 1-5-1, Higashi-Hiroshima 739-8529, Japan.
Mol Phylogenet Evol. 2007 Jan;42(1):236-47. doi: 10.1016/j.ympev.2006.06.024. Epub 2006 Jul 14.
In northern Australia, the debris-feeding termite Amitermes laurensis builds tall, wedge-shaped mounds in the northern part of Cape York Peninsula and Arnhem Land, where their habitats are seasonally flooded, and small dome shaped mounds in the southeastern part of Cape York Peninsula, where their habitats are well-drained. Phylogeographic analyses were conducted in 238 individuals from 30 populations using the mitochondrial cytochrome oxidase II (COII) gene. DNA sequences of 50 haplotypes were used to construct NJ, MP and ML trees. Phylogenetic trees for 16 Amitermes species showed monophyly of A. laurensis and the variation of A. laurensis mounds did not strongly correspond to the intraspecific phylogeny. It was observed that mounds with the same shape were constructed by phylogenetically different groups under similar environmental conditions and different mounds shapes were built by phylogenetically closely related groups under the different environmental conditions. Thus, phylogenetically close groups of A. laurensis, in different habitats, may adapt to environmental conditions by constructing different mound shapes. We also investigated the phylogeographic structure of A. laurensis. The significant positive correlation between genetic and geographic distances indicated isolation by distance, reflecting restricted dispersal ability of alates. Although the overall genetic structure of A. laurensis showed isolation by distance, we also identified two exceptions: (i) secondary contacts of genetically divergent lineages in southern Cape York Peninsula, and (ii) low genetic differences between geographically separated populations of Cape York Peninsula and Arnhem Land. Therefore, the phylogeography of A. laurensis may reflect continuous gene flow restricted to short distances and past changes of gene flow associated with the fluctuation of environmental conditions accompanying the changing sea levels in the Quaternary.
在澳大利亚北部，以碎屑为食的劳伦氏白蚁（Amitermes laurensis）在约克角半岛北部和阿纳姆地建造高大的楔形蚁丘，其栖息地会季节性被洪水淹没；而在约克角半岛东南部建造小型圆顶形蚁丘，其栖息地排水良好。利用线粒体细胞色素氧化酶II（COII）基因，对来自30个种群的238个个体进行了系统地理学分析。50个单倍型的DNA序列被用于构建NJ树、MP树和ML树。16种白蚁的系统发育树显示劳伦氏白蚁为单系群，且劳伦氏白蚁蚁丘的差异与种内系统发育并不强烈对应。观察到在相似环境条件下，系统发育不同的群体建造了相同形状的蚁丘，而在不同环境条件下，系统发育密切相关的群体建造了不同形状的蚁丘。因此，在不同栖息地的系统发育密切相关的劳伦氏白蚁群体，可能通过建造不同形状的蚁丘来适应环境条件。我们还研究了劳伦氏白蚁的系统地理结构。遗传距离和地理距离之间的显著正相关表明存在距离隔离，反映了有翅成虫扩散能力受限。虽然劳伦氏白蚁的整体遗传结构显示出距离隔离，但我们也发现了两个例外：（i）约克角半岛南部遗传分化谱系的二次接触；（ii）约克角半岛和阿纳姆地地理隔离种群之间的低遗传差异。因此，劳伦氏白蚁系统地理学可能反映了限于短距离的持续基因流以及过去与第四纪海平面变化伴随的环境条件波动相关的基因流变化。
