Schäffer Sylvia, Koblmüller Stephan
Institute of Biology, University of Graz, Graz, Austria.
PeerJ. 2020 Sep 11;8:e9710. doi: 10.7717/peerj.9710. eCollection 2020.
Bark beetles are feared as pests in forestry but they also support a large number of other taxa that exploit the beetles and their galleries. Among arthropods, mites are the largest taxon associated with bark beetles. Many of these mites are phoretic and often involved in complex interactions with the beetles and other organisms. Within the oribatid mite family Scheloribatidae, only two of the three nominal species of have been frequently found in galleries of bark beetles and on the beetles themselves. One of the species, , has a wide distribution range spanning over three ecozones of the world and is believed to be a host generalist, reported from numerous bark beetle and tree species. In the present study, phylogenetic analyses of one mitochondrial and two nuclear genes identified six well supported, fairly divergent clades within . which we consider to represent distinct species based on molecular species delimitation methods and largely congruent clustering in mitochondrial and nuclear gene trees. These species do not tend to be strictly host specific and might occur syntopically. Moreover, mito-nuclear discordance indicates a case of past hybridization/introgression among distinct species, the first case of interspecific hybridization reported in mites other than ticks.
树皮甲虫在林业中被视为害虫，但它们也为大量其他利用甲虫及其虫道的类群提供了生存支持。在节肢动物中，螨类是与树皮甲虫相关的最大类群。这些螨类中的许多是携播性的，并且常常与甲虫及其他生物存在复杂的相互作用。在甲螨科Scheloribatidae中，三个命名物种中只有两个经常在树皮甲虫的虫道和甲虫本身身上被发现。其中一个物种，分布范围广泛，跨越世界三个生态区，被认为是一种广食性寄主，在众多树皮甲虫和树种上都有报道。在本研究中，对一个线粒体基因和两个核基因进行的系统发育分析在该物种内确定了六个得到充分支持、差异较大的分支。基于分子物种界定方法以及线粒体和核基因树中大致一致的聚类情况，我们认为这些分支代表不同的物种。这些物种并非严格地具有寄主特异性，可能会在同一地点出现。此外，线粒体-核基因不一致表明在不同的该物种之间存在过去的杂交/基因渗入情况，这是蜱螨目以外的螨类中首次报道的种间杂交案例。
