Abstract
An increasing number of studies have shown that warming also influences the animal gut microbiome (altering the community structure and decreasing its diversity), which might further impact host fitness. Here, based on an analysis of the stomach and gut (the entire intestine: from the anterior intestine to the cloaca) microbiome in laboratory larva of giant salamanders (Andrias davidianus) under different living water temperatures (5, 15, and 25°C) at two sample time points (80 and 330 days after the acclimation), we investigated the potential effect of temperature on the gastrointestinal microbiome community. We found the significant Interaction between sampling time and temperature, or type (stomach and gut) on Shannon index in the gastrointestinal microbiome of the giant salamanders. We also found the significant difference in Shannon index among temperature groups within the same sample type (stomach or gut) at each sample time. 10% of variation in microbiome community could be explained by temperature alone in the total samples. Both the stomach and gut microbiomes displayed the highest similarity in the microbiome community (significantly lowest pairwise unweighted Unifrac distance) in the 25-degree group between the two sampling times compared to those in the 5-degree and 15-degree groups. Moreover, the salamanders in the 25°C treatment showed the highest food intake and body mess compared to that of other temperature treatments. A significant increase in the abundance of Firmicutes in the gastrointestinal microbiome on day 330 with increasing temperatures might be caused by increased host metabolism and food consumption. Therefore, we speculate that the high environmental temperature might indirectly affect both alpha and beta diversity of the gastrointestinal microbiome.
Highlights
The holobiont can function as a distinct biological system and plays an important role in metabolism, immunity, and development (Margulis and Fester, 1991; Rosenberg and Zilber-Rosenberg, 2018)
The captive individuals have prominent cold preference, with behavioral preference temperature lower than the reported optimal growth temperature in aquaculture (15–21◦C), and warm acclimation can’t improve their preferred temperature. These results suggest that the Chinese giant salamander may be sensitive to global warming
We investigate the changes in the gastrointestinal microbiome in a laboratory Chinese giant salamander population under the same diet and across different environmental temperatures (5, 15, and 25◦C) across two sampling times (80 and 330 days after the acclimation)
Summary
The holobiont (the host plus all of its microbes) can function as a distinct biological system and plays an important role in metabolism, immunity, and development (Margulis and Fester, 1991; Rosenberg and Zilber-Rosenberg, 2018). Three interesting studies have found an effect of environmental temperature on the gut microbial communities of ectothermic amphibians and reptiles. One study revealed that the gut microbial communities of laboratory raised tadpoles of the northern leopard frog (Lithobates pipiens) in warm (28◦C) temperature treatments exhibited a higher relative abundance of the phylum Planctomycetes and Actinobacteria and lowered relative abundance of Firmicutes and Proteobacteria than in the cool treatment (18◦C) (Kohl and Yahn, 2016). Those mediated through changes in host physiology, may result in significant changes in the gut microbial community (Kohl and Yahn, 2016). A third study found that +2–3◦C increase in temperature resulted in a 34% loss of populations’ microbiota diversity (number of OTUs) in the wild ectothermic common lizard Zootoca vivipara (Bestion et al, 2017). Understanding the threat to animal biodiversity posed by global warming will require studying the animal and their gastrointestinal microbiome
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