Department of Integrative Biology and Biodiversity Center, University of Texas at Austin, Austin, TX, 78712, USA.
J Chem Ecol. 2022 Apr;48(4):384-400. doi: 10.1007/s10886-022-01352-8. Epub 2022 Mar 14.
The sequestration by neotropical poison frogs (Dendrobatidae) of an amazing array of defensive alkaloids from oribatid soil mites has motivated an exciting research theme in chemical ecology, but the details of mite-to-frog transfer remain hidden. To address this, McGugan et al. (2016, Journal of Chemical Ecology 42:537-551) used the little devil poison frog (Oophaga sylvatica) and attempted to simultaneously characterize the prey mite alkaloids, the predator skin alkaloids, and identify the mites using DNA sequences. Heethoff et al. (2016, Journal of Chemical Ecology 42:841-844) argued that none of the mite families to which McGugan et al. allocated the prey was thought to possess alkaloids. Heethoff et al. concluded from analyses including additional sequences that the mite species were unlikely to be close relatives of the defended mites. We re-examine this by applying more appropriate phylogenetic methods to broader and denser taxonomic samples of mite sequences using the same gene (CO1). We found, over trees based on CO1 datasets, only weak support (except in one case) for branches critical to connecting the evolution of alkaloid sequestration with the phylogeny of mites. In contrast, a well-supported analysis of the 18S ribosomal gene suggests at least two independent evolutionary origins of oribatid alkaloids. We point out impediments in the promising research agenda, namely a paucity of genetic, chemical, and taxonomic information, and suggest how phylogenetics can elucidate at a broader level the evolution of chemical defense in prey arthropods, sequestration by predators, and the impact of alkaloids on higher-order trophic interactions.
新大陆毒蛙（箭毒蛙科）从食真菌螨中摄取了一系列令人惊叹的防御性生物碱，这激发了化学生态学领域一个令人兴奋的研究主题，但有关螨向蛙传递的细节仍不为人知。为了解决这个问题，McGugan 等人（2016 年，《化学生态学杂志》42：537-551）使用小恶魔毒蛙（Oophaga sylvatica），并试图同时对猎物螨生物碱、捕食者皮肤生物碱进行特征分析，并利用 DNA 序列鉴定螨。Heethoff 等人（2016 年，《化学生态学杂志》42：841-844）认为，McGugan 等人分配给猎物的螨科都不被认为具有生物碱。Heethoff 等人的结论是，从包括额外序列的分析中，这些螨种不太可能是受防御的螨的近亲。我们通过应用更合适的系统发育方法，在更广泛和更密集的螨序列分类样本中，使用相同的基因（CO1）重新检验了这一点。我们发现，基于 CO1 数据集的系统发育树中，除了一种情况外，只有微弱的支持证据支持与生物碱摄取的进化与螨的系统发育相连接的分支。相比之下，对 18S 核糖体基因的充分支持分析表明，食真菌螨生物碱至少有两个独立的进化起源。我们指出了有希望的研究议程中的障碍，即遗传、化学和分类学信息的缺乏，并提出了系统发育学如何在更广泛的层面上阐明猎物节肢动物的化学防御、捕食者的摄取以及生物碱对高级营养相互作用的影响。
