The gut microbiome is shaped by both host diet and host phylogeny. However, separating the relative influence of these two factors over long periods of evolutionary time is often difficult. We conducted a 16S rRNA gene amplicon-based survey of the gut microbiome from 237 individuals and 19 species of omnivorous cockroaches from the order Blattodea. The order Blattodea represents an ancient lineage of insects that emerged over 300 million years ago, have a diverse gut microbiota, and have a typically gregarious lifestyle. All cockroaches shared a broadly similar gut microbiota, with 66 microbial families present across all species and 13 present in every individual examined. Although our network analysis of the cockroach gut microbiome showed a large amount of connectivity, we demonstrated that gut microbiota cluster strongly by host species. We conducted follow-up tests to determine if cockroaches exhibit phylosymbiosis, or the tendency of host-associated microbial communities to parallel the phylogeny of related host species. Across the full data set, gut microbial community similarity was not found to correlate with host phylogenetic distance. However, a weak but significant phylosymbiotic signature was observed using the matching cluster metric, which allows for localized changes within a phylogenetic tree that are more likely to occur over long evolutionary distances. This finding suggests that host phylogeny plays a large role in structuring the cockroach gut microbiome over shorter evolutionary distances and a weak but significant role in shaping the gut microbiome over extended periods of evolutionary time.

IMPORTANCE The gut microbiome plays a key role in host health. Therefore, it is important to understand the evolution of the gut microbiota and how it impacts, and is impacted by, host evolution. In this study, we explore the relationship between host phylogeny and gut microbiome composition in omnivorous, gregarious cockroaches within the Blattodea order, an ancient lineage that spans 300 million years of evolutionary divergence. We demonstrate a strong relationship between host species identity and gut microbiome composition and found a weaker but significant role for host phylogeny in determining microbiome similarity over extended periods of evolutionary time. This study advances our understanding of the role of host phylogeny in shaping the gut microbiome over different evolutionary distances.

肠道微生物组由宿主饮食和宿主系统发育决定。但是，很难将这两个因素在较长的进化时间内的相对影响分开。我们对来自Blattodea的237个个体和19种杂食性蟑螂的肠道微生物组进行了基于16S rRNA基因扩增子的调查。Blattodea目代表了三亿多年前出现的古老昆虫谱系，具有多种肠道菌群，并具有典型的群居生活方式。所有的蟑螂都有一个广泛相似的肠道菌群，所有物种中都有66个微生物家族，每一个被检查的个体中都有13个微生物家族。尽管我们对蟑螂肠道微生物组的网络分析显示出大量的连通性，但我们证明了肠道微生物群被宿主物种强烈聚集。我们进行了跟踪测试，以确定蟑螂是否表现出共生共生，或与宿主相关的微生物群落与相关宿主物种的系统发育平行的趋势。在整个数据集中，未发现肠道微生物群落相似性与宿主系统发生距离相关。但是，使用匹配聚类量度观察到弱而显着的共生共生特征，这使得系统发生树内的局部变化更可能发生在较长的进化距离上。这一发现表明宿主系统发育在较短的进化距离上对蟑螂肠道微生物组的结构起着重要的作用，而在进化的延长时间内对肠道微生物组的形成起着微弱但重要的作用。

重要性肠道微生物组在宿主健康中起关键作用。因此，重要的是要了解肠道微生物群的进化及其对宿主进化的影响和影响。在这项研究中，我们探索了Blattodea阶中的杂食性，群居蟑螂的宿主系统发育与肠道微生物组组成之间的关系。Blattodea阶是跨越3亿年进化差异的古老世系。我们证明了宿主物种的身份与肠道微生物组组成之间的密切关系，并发现宿主系统发育在确定微生物组在进化时间上的相似性方面的作用较弱但很重要。这项研究提高了我们对宿主系统发育在不同进化距离上塑造肠道微生物组的作用的理解。