Ecological and molecular phylogenetic analysis of the distribution expansion process of spider mites in Southeast and East Asia

本文研究了东南亚和东亚地区两种螨（叶螨）滞育能力和线粒体DNA （COI）的变化，以阐明其在该地区的分布扩展模式。日本（绿色形式）种群的滞育率呈临床变化，南方种群的滞育能力很低。在东南亚和东亚的所有种群中也观察到这种低滞育能力。众所周知，这种螨虫起源于地中海地区，并在短时间内扩大了其在世界各地的分布范围。目前基于COI基因的系统发育分析证实，所有研究地区的种群都包含在一个单一的聚类中，COI序列的变化很小。结果表明，荨麻疹是包括日本在内的亚洲地区的入侵物种，在分布扩张的过程中，荨麻疹丧失了滞育能力，但获得了较高的扩散能力，以适应温暖的气候和持续的食物供应。除冲绳岛外，日本大部分kanzawai种群的滞育率均在90%以上。滞育率在台湾各种群间差异很大。在越南北部的种群中也观察到这种遗传多样化的滞育能力。来自泰国的种群，包括来自北方的种群，表现出非常低的滞育能力，而来自印度尼西亚西爪哇和菲律宾马尼拉的种群，尽管分布在热带地区，却保持了很高的滞育能力。因此，在T.kanzawai中，滞育能力与纬度之间没有明显的关系，滞育不受自然选择的影响。基于COI序列的系统发育分析表明，来自本州及南部的所有种群，包括来自韩国、台湾、越南和泰国的种群，在遗传上均为同源，形成了一个单一的进化支。而北海道北部的种群有13个单倍型，遗传分化程度较高。上述结果表明，kanzawai原产于北方地区，最近才将分布范围扩大到南方地区。少

We studied the variation in diapause capacity and the mitochondrial DNA (COI) variation in two species of spider mites (Tetranychus urticae and T.kanzawai) for populations collected from Southeast and East Asia, to elucidate their distribution expansion patterns over the area. Japanese T.uritice (green form) populations showed a clinal change in diapause percentage and populations in the South had a very low diapause capacity. This low diapause capacity was also observed in all populations from Southeast and East Asia. The mites are known to originate from the Mediterranean areas and to have expanded its distribution range over the world within a short period. The present phylogenetic analysis based on COI gene confirmed that all populations from the areas studied are included in a single cluster with very little variation in the COI sequences. The results combined showed that T.urticae is an invasive species in Asia, including Japan, and in the process of distribution expansion the mi … More tes lost its diapause capacity, while they obtained high dispersal capacity, to adjust warm climates with continuous food availability.Most Japanese T.kanzawai populations, except those from Okinawa Islands, exhibited diapause percentages higher than 90%. Diapause percentages varied greatly among populations from Taiwan. This genetically diversified diapause capacity was also observed in populations from northern Vietnam. While populations from Thailand, including those from in the North, showed very low diapause capacity, populations from West Jawa, Indonesia and those from Manila, Philippines maintained high diapause capacity, in spite of their distribution in the tropics. Thus, in T.kanzawai no clear relationship was observed between dipause capacity and latitude and diapause was not subject to natural selection. The phylogenetic analysis based on the COI sequences showed that all populations from Honshu and southward, including those from Korea, Taiwan, Vietnam, and Thailand were genetically homogeneous and formed a single clade. However, populations from northern Hokkaido had 13 haplotypes, thus showing a comparatively high genetic differentiation. The results above implied that T.kanzawai originates in northern area and has expanded its distribution range to southern areas very recently. Less