Holmes Iris A, Martínez-Fonseca José G, von May Rudolf, Sealey Briana A, Cerda Peter A, Grundler Maggie R, Westeen Erin P, Nondorf Daniel, Larson Joanna G, Myers Christopher R, Hendry Tory A
Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY 14853, United States.
Department of Microbiology, Cornell University, Ithaca, NY 14853, United States.
ISME Commun. 2025 Aug 23;5(1):ycaf146. doi: 10.1093/ismeco/ycaf146. eCollection 2025 Jan.
Host-associated bacteria vary in the number of host species they occupy. By colonizing many host species, host generalists can have disproportionate ecological impacts and should gain an evolutionary advantage when host species availability varies. However, past work has shown that many bacterial lineages are host specific. We hypothesized that constraints on bacterial host generalism will differ depending on ecological context. To test this, we assessed patterns of diversity and specialization in the cloacal microbiomes of reptile communities from the temperate zone to the tropics, a 10-fold increase in host species richness. We found that some host-specific lineages increased in richness along with their hosts, while generalist lineages did not. Generalist lineages were able to attain their highest host prevalence when host diversity was lower. In our highest diversity host communities, we found that the successful generalists, typically Proteobacteria, were disproportionately likely to co-occur with one another across evolutionarily disparate hosts. Our data indicated that bacterial lineages may adapt to the evolutionary pressures of high diversity host communities either by specializing on hosts or by forming cohorts of co-occurring bacterial lineages. Previous research across vertebrate gut microbiomes has shown that mutually beneficial relationships between bacterial lineages are widespread. Our work further supports that finding and contextualizes it within a range of host community diversity.
与宿主相关的细菌在其所占据的宿主物种数量上存在差异。宿主泛化菌通过定殖于多种宿主物种，可能会产生不成比例的生态影响，并且当宿主物种的可利用性发生变化时，应能获得进化优势。然而，过去的研究表明，许多细菌谱系具有宿主特异性。我们推测，对细菌宿主泛化的限制将因生态环境而异。为了验证这一点，我们评估了从温带到热带的爬行动物群落泄殖腔微生物群的多样性和特化模式，宿主物种丰富度增加了10倍。我们发现，一些宿主特异性谱系的丰富度随着其宿主的增加而增加，而泛化谱系则不然。当宿主多样性较低时，泛化谱系能够达到其最高的宿主流行率。在我们宿主多样性最高的群落中，我们发现，成功的泛化菌，通常是变形菌门，在进化上截然不同的宿主之间相互共存的可能性不成比例地高。我们的数据表明，细菌谱系可能通过专门定殖于宿主或通过形成共生细菌谱系群体来适应高多样性宿主群落的进化压力。此前对脊椎动物肠道微生物群的研究表明，细菌谱系之间的互利关系很普遍。我们的工作进一步支持了这一发现，并将其置于一系列宿主群落多样性的背景中。
