The Circadian Rhythm of the Behavior and Gut Microbiota in Dybowski's Frogs (Rana dybowskii) during the Autumn Migration Period.

Abstract

Many amphibian behaviors and physiological functions adapt to daily environmental changes through variations in circadian rhythms. However, these adaptations have yet to be reported in Dybowski's frog (Rana dybowskii). We aimed to elucidate the dynamic changes in the behavior and gut microbiota of R. dybowskii within a 24 h cycle during their migration to hibernation sites. Thus, we monitored their behavior at 4 h intervals and collected samples for microbiome analysis. We found that the juvenile frogs arrived at hibernation sites earlier than the adults. Among the adults, the male frogs arrived earlier. The richness and diversity of the gut microbiota in the adult R. dybowskii were lowest at 14:00. At 6:00, the differences between the males and females were most significant. At 18:00, there was an increase in the activity of Bacteroides, Coprobacillus, Ruminococcus, and Dorea in the intestinal tracts of the male frogs, whereas in the intestinal tract of the female frogs, there was an increase in the activity of Pseudoramibacter_Eubacterium, Desulfovibrio, Anaerotruncus, and PW3. This indicated diurnal rhythmic variations in the gut microbiota and significant sex-based differences in the microbial activity at different time points. Our findings contribute to the understanding of the circadian rhythm of R. dybowskii and provide crucial insights into improving breeding strategies.