Dabert Miroslawa, Proctor Heather, Dabert Jacek
Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
Mol Phylogenet Evol. 2016 Aug;101:75-90. doi: 10.1016/j.ympev.2016.05.004. Epub 2016 May 11.
With nearly 6000 named species, water mites (Hydrachnidiae) represent the largest group of arachnids to have invaded and extensively diversified in freshwater habitats. Water mites together with three other lineages (the terrestrial Erythraiae and Trombidiae, and aquatic Stygothrombiae), make up the hyporder Parasitengonina, which is characterized by having parasitic larvae and predatory nymphs and adults. Relationships between the Hydrachnidiae and other members of the Parasitengonina are unclear, as are relationships among the major lineages of water mites. Monophyly of water mites has been asserted, with the possible exception of the morphologically distinctive Hydrovolzioidea. Here we infer the phylogeny of water mites using multiple molecular markers and including representatives of all superfamilies of Hydrachnidiae and of almost all other Parasitengonina. Our results support a monophyletic Parasitengonina including Trombidiae, Stygothrombiae, and Hydrachnidiae. A monophyletic Hydrachnidiae, including Hydrovolzioidea, is strongly supported. Terrestrial Parasitengonina do not form a monophyletic sister group to water mites. Stygothrombiae is close to water mites but is not nested within this clade. Water mites appear to be derived from ancestors close to Stygothrombiae or the erythraoid group Calyptostomatoidea; however, this relationship is not clear because of extremely short branches in this part of the parasitengonine tree. We recovered with strong support all commonly accepted water mite superfamilies except for Hydryphantoidea, which is clearly paraphyletic. Our data support the previously proposed clades Protohydrachnidia (Hydrovolzioidea and Eylaoidea), Euhydrachnidia (all remaining superfamilies), and the euhydrachnid subclade Neohydrachnidia (Lebertioidea, Hydrachnoidea, Hygrobatoidea, and Arrenuroidea). We found that larval leg structure and locomotory behavior are strongly congruent with the molecular phylogeny. Other morphological and behavioral characters, including host choice, are not as strongly correlated with phylogeny. Molecular dating suggests that the Hydrachnidiae arose about 235MYA, and that Neohydrachnidia began to diversify about 155MYA. Our results provide a strong framework for classification and for further elaboration at finer taxonomic scales, which will allow testing of ecological and behavioral hypotheses associated with the transition from terrestrial to aquatic life.
水螨（Hydrachnidiae）有近6000个已知物种，是侵入淡水生境并在其中广泛分化的最大蛛形纲动物类群。水螨与其他三个谱系（陆生的赤螨科Erythraiae和绒螨科Trombidiae，以及水生的隐绒螨科Stygothrombiae）共同构成了副寄生螨亚目Parasitengonina，其特征是幼虫寄生，若虫和成虫捕食。水螨科与副寄生螨亚目的其他成员之间的关系尚不清楚，水螨的主要谱系之间的关系也是如此。除形态独特的水伏螨总科Hydrovolzioidea可能例外，水螨的单系性已得到认定。在这里，我们使用多种分子标记推断水螨的系统发育，包括水螨科所有总科以及几乎所有其他副寄生螨亚目的代表。我们的结果支持包括绒螨科、隐绒螨科和水螨科的单系副寄生螨亚目。包括水伏螨总科在内的单系水螨科得到了有力支持。陆生副寄生螨亚目并非形成水螨的单系姐妹群。隐绒螨科与水螨关系密切，但并不嵌套在这个分支内。水螨似乎起源于与隐绒螨科或赤螨形类群Calyptostomatoidea相近的祖先；然而，由于副寄生螨谱系这一部分的分支极短，这种关系并不明确。除明显并系的水狼螨总科Hydryphantoidea外，我们得到了所有普遍认可的水螨总科的有力支持。我们的数据支持先前提出的原水螨类（Protohydrachnidia，水伏螨总科和艾氏螨总科Eylaoidea）、真水螨类（Euhydrachnidia，所有其余总科）以及真水螨类亚分支新水螨类（Neohydrachnidia，列氏螨总科Lebertioidea、水蛛螨总科Hydrachnoidea、湿螨总科Hygrobatoidea和异足螨总科Arrenuroidea）。我们发现幼虫的腿部结构和运动行为与分子系统发育高度一致。其他形态和行为特征，包括宿主选择，与系统发育的相关性则没那么强。分子定年表明水螨科大约在2.35亿年前出现，新水螨类大约在1.55亿年前开始分化。我们的结果为分类以及在更精细的分类尺度上进一步细化提供了一个有力的框架，这将有助于检验与从陆生向水生生活转变相关的生态和行为假说。
