Gibson, Nguyen, Ahn and Crandall Published in Scientific Reports

May 28, 2019

Keylie Gibson and Bryan Nguyen (graduate research assistants with the Computational BIology Institute and PhD students in the Department of Biological Sciences), Michelle Ahn (former research assistant with the CBI and M.S. in Biological Sciences graduate), and Keith Crandall (Director of the CBI and professor in the Department of Epidemiology and Biostatistics) co-authored an article published in Scientific Reports on May 28th, 2019, titled "Gut microbiome differences between wild and captive black rhinoceros – implications for rhino health". A number of recent studies have shown the importance of the mammalian gut microbiome in host health. In the context of endangered species, a few studies have examined the relationship between the gut microbiome in wild versus captive populations due to digestive and other health issues. Unfortunately, the results seem to vary across taxa in terms of captive animals having higher, lower, or equivalent microbiome diversity relative to their wild counterparts. Here, the authors focus on the black rhinoceros as captive animals suffer from a number of potentially dietary related health effects. The authors compared gut microbiomes of wild and captive black rhinos to test for differences in taxonomic diversity (alpha and beta) and in functional diversity of the microbiome. They incorporated a more powerful metagenomic shotgun sequencing approach rather than a targeted amplification of the 16S gene for taxonomic assignment of the microbiome. Their results showed no significant differences in the alpha diversity levels between wild and captive black rhinos, but significant differences in beta diversity. The authors found that bacterial taxa traditionally associated with ruminant guts of domesticated animals had higher relative abundances in captive rhinos. Their metagenomic sequencing results suggest that unknown gut microbes of wild rhinos are being replaced by those found in conventional human-domesticated livestock. Wild rhinos have significantly different functional bacterial communities compared to their captive counterparts. Functional profiling results showed greater abundance of glycolysis and amino acid synthesis pathways in captive rhino microbiomes, representing an animal receiving sub-optimal nutrition with a readily available source of glucose but possibly an imbalance of necessary macro and micronutrients. Given the differences observed between wild and captive rhino gut microbiomes, the authors make a number of recommendations for potentially modifying captive gut microbiome to better reflect their wild counterparts and thereby hopefully improve overall rhino health in captivity.


Update: this article was featured on the Smithsonian's National Zoo and Conservation Biology Institute website, located here.