关键词:
fungus-growing ants
Trachymyrmex septentrionalis
host-associated microbiome
microbial community ecology
摘要:
Like all fungus-growing ants, Trachymyrmex septentrionalis engages in an obligate mutualism with a Basidiomycete fungus that it raises as its primary nutrition source. Therefore, the success of the symbiosis is dependent upon the health of the fungus garden containing this fungus, which may be affected by the composition of its microbiome. Most of what is known about fungus garden microbiomes comes from studies of the Neotropical fungus growing ants, especially the most evolutionarily derived and economically impactful "leaf-cutting" species. Although fungus-farming ants inhabit a vast range, little is known about how dispersal of microbes from their biogeographically and temporally distinct habitats affect the composition and function of fungus garden microbiomes, which ultimately may affect symbiotic fitness. Therefore, this dissertation will infer the effects of dispersal from environmental microbiomes on the composition of the Trachymyrmex septentrionalis fungus garden microbiome across these ants' geographic range and active seasons, and test the potential consequences of these dispersal events on symbiotic fitness. The extensive fieldwork required to conduct these types of studies inevitably creates delays between sample collection and processing. Therefore, a robust sample preservation strategy is needed to maintain the composition of the microbial community during these delays. This work validates a preservative buffer that is non-hazardous, cost-effective, and preserved microbial composition with high fidelity, making it broadly applicable for microbial community ecology studies. To investigate the effects of environmental dispersal on T. septentrionalis fungus garden microbiomes across their geographic range, we analyzed 16S rRNA gene sequence data from > 100 colonies that we collected from six states, and 90 metagenomes from five of those states. We found that fungus garden microbiome composition and its encoded functional genes both exhibited biogeograph