Ambient temperature alters body size and gut microbiota of Xenopus tropicalis.

Temperature is important to determine physiological status of ectotherms. However, it is still not fully understood how amphibians and their symbiotic microbiota acclimate to ambient temperature. In this study, we investigated the changes of gut microbiota of Xenopus tropicalis at different temperatures under controlled laboratory conditions. The results showed that microbial communities were distinct and shared only a small overlap among froglet guts, culture water and food samples. Furthermore, the dominant taxa harbored in the gut exhibited low relative abundance in water and food. It indicates that bacterial taxa selected by amphibian gut were generally of low abundance in the external environment. Temperature could affect beta-diversity of gut microbiota in terms of phylogenetic distance, but it did not affect alpha diversity. The composition of gut microbiota was similar in warm and cool treatments. However, signature taxa in different temperature environments were identified. The relationships between temperature, gut microbiota and morphology traits of X. tropicalis revealed in this study help us to predict the consequences of environmental changes on ectothermic animals.

Divergence of Fecal Microbiota and Their Associations With Host Phylogeny in Cervinae.

Gastrointestinal microbiota may shape the adaptation of their hosts to different habitats and lifestyles, thereby driving their evolutionary diversification. It remains unknown if gastrointestinal microbiota diverge in congruence with the phylogenetic relationships of their hosts. To evaluate the phylosymbiotic relationships, here we analyzed the compositions of fecal microbiota of seven Cervinae species raised in the Chengdu Zoo. All sampled animals were kept in the same environmental condition and fed identical fodder for years. Results showed that Firmicutes and Bacteroidetes were dominant in their fecal microbiota. Even though some bacteria (e.g., Ruminococcaceae) were found to be common in the feces of all investigated species, some genera (e.g., Sharpea and Succinivibrio) were only observed in animals with particular digestive systems. As for the intraspecies variations of microbial communities, only a few operational taxonomic units (OTUs) were shared among replicates of the same host species although they accounted for most of the total abundance. Correlation was observed between the fecal microbiota divergence and host phylogeny, but they were not congruent completely. This may shed new light on the coevolution of host species and their microbiota.