针叶小爪螨板栗和杉木种群间的遗传分化和杂交试验

为明确针叶小爪螨Oligonychus ununguis（Jacobi）山东板栗种群和浙江杉木种群的遗传分化程度，本研究对其基因序列（线粒体COⅠ和核糖体ITS2）进行了比较，并通过杂交试验测定了两者间的杂交亲和性.采用PCR产物直接测序法获得410 bp的COⅠ片段及469 bp（板栗种群）和513 bp（杉木种群）的完整ITS2序列，COⅠ及ITS2序列在两种群间的差异分别为10.5%~10.8%和15.2%~15.7%.杂交试验表明两种群间存在完全的生殖隔离.根据两者间的序列差异和杂交结果，初步认为山东板栗和浙江杉木上的小爪螨可能是两个不同的种

Genetic differentiation and cross-breeding experiments between Oligonychus ununguis (Acari:Tetranychidae) populations from host plants Castanea mollissima and Cunninghamia lanceolata

To determine the differentiation degree within the spruce spider mites, Oligonychus ununguis（Jacobi）, two populations of the mite on chestnut Castanea mollissima from Shandong Province and on fir Cunninghamia lanceolata from Zhejiang Province were used for analyzing the sequence variation of the second internal transcribed spacer 2 （ITS2） of nuclear ribosomal DNA and part of the mitochondrial cytochrome oxidase I gene （COⅠ）. The reproductive compatibility between the two populations was examined through cross-breeding experiments. The results indicated that ITS2 gene from chestnut and fir individuals is 469 bp and 513 bp in length, respectively. Nucleotide divergence of ITS2 gene was 15.2%-15.7% between the two populations. The mites collected from chestnut differed from those collected from fir by 10.5%-10.8% of the nucleotide divergence in COⅠ sequences. Cross-breeding experiments between the two populations displayed their completely reproductive incompatibility. Therefore, the tested mite populations are probably two different species according to the divergences of DNA sequences and reproductive isolation between them.