彩虹锹甲不同发育阶段肠道真菌群落特征研究

Characteristics of gut fungal community at different developmental stages of the rainbow stag beetle Phalacrognathus muelleri (Coleoptera: Lucanidae)

摘要:

【目的】肠道微生物中的真菌群落在宿主生命活动中具有多种功能。锹甲是常见的腐食性甲虫，但目前对其肠道真菌群落的研究较少，本研究分析彩虹锹甲(Phalacrognathus muelleri)不同发育阶段的肠道真菌群落结构和多样性，试图阐明彩虹锹甲在不同发育阶段中肠道真菌群落的特征。【方法】本研究通过高通量测序(Illumina MiSeq)技术对彩虹锹甲不同发育阶段(包括新生幼虫、成熟幼虫、成虫)之间肠道真菌群落结构进行比较研究，分析其α多样性、β多样性和功能预测。【结果】彩虹锹甲肠道优势真菌类群为假丝酵母属(Candida)、Phialocephala、青霉属(Penicillium)、烧瓶状霉属(Lecythophora)。肠道真菌群落组成与多样性在幼虫期和成虫期存在显著差异，成虫与幼虫食性差别可能是导致肠道真菌群落组成和多样性差异的重要原因。功能预测结果显示，幼虫肠道中含有更高的内共生菌多样性与相对丰度，说明幼虫可能更加依赖其肠道有益真菌来获得充分的养分。β零模型结果显示，成虫肠道对其真菌群落具有更强的过滤作用，从而选择特定的肠道真菌类群，导致成虫肠道真菌群落共现网络具有更高的稳定性，增强成虫对环境波动的适应能力。【结论】本研究发现彩虹锹甲不同发育阶段参与食物降解的功能真菌类型不同，幼虫可能对肠道真菌的依赖性更强，而成虫肠道较强的选择作用有助于选择特定真菌类群和保持肠道真菌群落稳定。本研究有助于更好理解锹甲肠道真菌群落的多样性，为开展腐栖甲虫作为生态系统重要功能群的利用与保护提供更多理论参考。

Abstract:

[Objective] Gut fungal microorganisms play multiple roles in the life history of their hosts as indispensable part of gut microbiota. Although stag beetles are common saprophytic insects, little is known about their gut fungal community. In this study, we compared the structure and diversity of gut fungi at different developmental stages of the rainbow stag beetle, Phalacrognathus muelleri, aiming to reveal the characteristics of the fungi at different developmental stages of this insect. [Methods] We employed high-throughput sequencing (Illumina MiSeq) to study the gut fungal community structure in the newborn larvae, mature larvae, and adults of P. muelleri. Further, we analyzed alpha and beta diversity and carried out functional prediction for the fungi. [Results] The predominant fungal genera in the gut of P. muelleri were Candida, Phialocephala, Penicillium, and Lecythophora. The composition and diversity of the gut fungal community were significantly different between the larvae and adults, which may be associated with their different diets. The functional prediction showed that endosymbiotic fungi in the larval gut had higher diversity and relative abundance, suggesting that the larvae might depend more on the beneficial fungal taxa in the gut to obtain nutrients. The results of the abundance-based β-null deviation showed that the adult gut exerted a stronger filtering effect to select specific fungal taxa. Thus, the adults might build a more stable co-occurrence network of gut fungal community which supported them to adapt to the environmental fluctuations. [Conclusion] Different groups of functional fungi are involved in the food degradation of P. muelleri at different developmental stages. The larvae may depend more on gut fungi, and the adult gut has strong filtering effect to select specific groups of fungi and maintain the stability of the gut fungal community. Our study enhances our understanding of the gut microbiota of stag beetles, which can aid in the conservation and utilization of these saprophytic beetles as an important functional group in ecosystems.