Abstract
Host-associated microbial communities are impacted by external and within-host factors, i.e., diet and feeding behavior. For organisms known to have a circadian rhythm in feeding behavior, microbiome composition is likely impacted by the different rates of microbe introduction and removal across a daily cycle, in addition to any diet-induced changes in microbial interactions. Here, we measured feeding behavior and used 16S rRNA sequencing to compare the microbial community across a diel cycle in two distantly related species of Daphnia, that differ in their life history traits, to assess how daily feeding patterns impact microbiome composition. We find that Daphnia species reared under similar laboratory conditions have significantly different microbial communities. Additionally, we reveal that Daphnia have daily differences in their microbial composition that correspond with feeding behavior, such that there is greater microbiome diversity at night during the host's active feeding phase. These results highlight that zooplankton microbiomes are relatively distinct and are likely influenced by host phylogeny.
Highlights
The structure and function of host-associated microbial communities are linked with both intrinsic host factors and external factors
In D. magna, increased bacterial diversity at night corresponded with an increase in the relative abundance of Arcticibacterium, a decrease in Limnohabitans, and a large increase in the relative abundance of rare taxa each appearing at less than 5% abundance, though no rare taxa became prominent enough to surpass any of the taxa consistently present at >5% relative abundance
We found that both Daphnia species had significantly higher feeding rates during the night than the day (Fig 2b, D. magna: paired t-test p = 0.008, D. dentifera: paired t-test p < 0.0001)
Summary
The structure and function of host-associated microbial communities are linked with both intrinsic host factors and external factors. Diet quality and variety influence microbiome composition; for example, mice transitioned from wild diets to controlled laboratory diets experienced shifts in microbiome composition and microbial functional pathways associated with carbohydrate metabolism, sugar metabolism, and motility [1]. These compositional and functional changes correlate with changes in host behavior [2], host immune function [3], and other physiological functions [4]. There are few studies that link changes in feeding behavior and microbial composition, despite the downstream effects changes in the microbiome can have on host survival, fitness, and immunity [6]
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