Avenues of future research
A major objective for future investigations on the daily rhythms of the
gut microbiome is to quantify their prevalence and strength across
natural populations. Currently, our knowledge on gut microbial
oscillations largely stems from laboratory mice, whilst our
understanding of circadian rhythms of wildlife is largely restricted to
behaviour 61. To understand the adaptive significance
of circadian rhythms and their entrainment by the gut microbiota, we
need to move the study of circadian rhythms to natural populations. This
is particularly true given the importance of food intake on system-wide
circadian rhythms, because feeding times of captive animals generally do
not mirror foraging regimes of wild counterparts. As such, whilst
studies on captive animals may help disentangle drivers of circadian
rhythms, they may not actually reflect circadian rhythms in nature or
capture how the interactions between multiple environmental and social
cues act to entrain rhythms. Below we briefly outline how integrating
gut microbiome and circadian rhythm research in wildlife can advance
several outstanding questions in ecology (Fig. 3).