Fecal metagenomics study reveals that a low-fiber diet drove the migration of wild Asian elephants in Xishuangbanna, China. feces metagenome

The rare northward migration of wild Asian elephants in Xishuangbanna, China has attracted global attention. Elephant migration is a complex ecological process, and the factors driving this long-distance migration have not been determined. In this study, fresh dung samples were collected from captive and wild Asian elephants as well as breast-fed calves in the Wild Elephant Valley of Xishuangbanna to explore the relationship between the diet, gut microbiota, and migration of Asian elephants based on metagenomic sequencing analyses. The main bacterial taxa enriched in the breast-fed Asian elephant (BAE) group were Bacteroides fragilis, Escherichia coli, and Prevotella_sp_CAG_279, and the main carbohydrate-active enzymes (CAZymes) enriched in the BAE group were GH2, GH20, GH92, GH97, GH38, GH23, and GH43, which were compatible with the diet (i.e., breast milk). Bacterial taxa enriched in captive Asian elephants (CAEs) were mainly Butyrivibrio, Treponema, and Fibrobacter succinogenes, and the enriched lignocellulose-degrading enzymes mainly included GH25, GH10, and GH9 as well as cellulase (EC 3.2.1.4), consistent with the high-fiber diet. The main bacterial taxa enriched in wild Asian elephants (WAEs) were Ruminococcus and Eubacterium, and the enriched CAZymes included GH109, GH20, GH33, GH28, GH106, and GH39. The abundance of lignocellulose-degrading bacteria and CAZyme contents were low in WAEs, indicating that it was difficult for the gastrointestinal microbiota to process high-fiber foods, explaining the low-fiber diet in this group. These findings indicate that wild elephant herds migrated in search of adequate food with low fiber contents.