Diets Alter the Gut Microbiome of Crocodile Lizards

Abstract

The crocodile lizard is a critically endangered reptile, and serious diseases have been found in this species in recent years, especially in captive lizards. Whether these diseases are caused by changes in the gut microbiota and the effect of captivity on disease remains to be determined. Here, we examined the relationship between the gut microbiota and diet and disease by comparing the fecal microbiota of wild lizards with those of sick and healthy lizards in captivity. The gut microbiota in wild crocodile lizards was consistently dominated by Proteobacteria (∼56.4%) and Bacteroidetes (∼19.1%). However, the abundance of Firmicutes (∼2.6%) in the intestine of the wild crocodile lizards was distinctly lower than that in other vertebrates. In addition, the wild samples from Guangdong Luokeng Shinisaurus crocodilurus National Nature Reserve also had a high abundance of Deinococcus–Thermus while the wild samples from Guangxi Daguishan Crocodile Lizard National Nature Reserve had a high abundance of Tenericutes. The gut microbial community in loach-fed crocodile lizards was significantly different from the gut microbial community in the earthworm-fed and wild lizards. In addition, significant differences in specific bacteria were detected among groups. Notably, in the gut microbiota, the captive lizards fed earthworms resulted in enrichment of Fusobacterium, and the captive lizards fed loaches had higher abundances of Elizabethkingia, Halomonas, Morganella, and Salmonella, all of which are pathogens or opportunistic pathogens in human or other animals. However, there is no sufficient evidence that the gut microbiota contributes to either disease A or disease B. These results provide a reference for the conservation of endangered crocodile lizards and the first insight into the relationship between disease and the gut microbiota in lizards.

Captivity Influences Gut Microbiota in Crocodile Lizards (Shinisaurus crocodilurus)

“…In addition, the gut microbiota is similar to lizards in other reptile categories (Costello et al, 2010;Colston et al, 2015;Yuan et al, 2015). Interestingly, previous study on gut microbiota of crocodile lizards in wild and captive populations reported that Proteobacteria and Bacteroidetes were primary, while the proportion of Firmicutes is lower than was detected in this study (Jiang et al, 2017). The potential reason for the discrepancy between the two studies could be the sampling methods used.…”

“…The potential reason for the discrepancy between the two studies could be the sampling methods used. Jiang et al (2017) used cloacal swabs for sampling, whereas fecal sampling was utilized in the present study. It has been demonstrated that the fecal communities were largely similar to hindgut microbial communities in lizards, thus becoming an acceptable indicator in the gut region for microbial diversity (Kohl et al, 2017).…”

“…However, like other captive species, some serious challenges are posed by the crocodile lizards during capacity in the nature reserves (Snyder et al, 1996). For example, the captive population has been plagued by various unknown diseases, nutritional deficiency, and low reproductive rates (Jiang et al, 2017).…”

“…Thus, promoting the conservation of endangered species by studying gut microbiota has been receiving increasing attention and has become a hot topic of conservation biology (e.g., Zhu et al, 2011;Wu et al, 2017). With limited studies conducted on the lizard gut microbiota, factors such as diet (Hong et al, 2011;Jiang et al, 2017), gender (Martin et al, 2010), adaptation (Ren et al, 2016), captive breeding Kohl et al, 2017), and even climate change (Bestion et al, 2017) have been demonstrated to affect the gut microbiota.…”

The development of gut microbiota in ostriches and its association with juvenile growth

“…After the first week, the yolk sac has largely been absorbed and they switch to external sources of food (Deeming 1999), mainly plant matter which has a high proportion of fibre. Diet has been shown to have major effects on the gut microbiome of animals (Koenig et al 2011;Muegge et al 2011;Jiang et al 2017), so it is likely that the dietary switch during this time has a direct impact on the differences we see in the gut community of 1-and 2-week-old chicks. Partly because of this switch from yolk to external food sources, it is generally recognized that the early posthatch period is a critical stage for the growth and health of poultry (Gilbert et al 2010;Cheled-Shoval et al 2011;Pan & Yu 2014).…”