Animals experience novel stressors inherent to captive environments. Some species are able to adapt to new environments with little consequence, while others display behavioral changes and health concerns. The gut microbiome of animals is also impacted by the captive environment. The gut microbiome is important to immune health, metabolism, hormone regulation, and even behavior. Captive animals often have less diverse gut microbiomes than their wild counterparts. The shifting of the microbial community in captivity may be connected to prevailing health issues. Zoo managed African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) experience low reproductive rates, obesity, and gastrointestinal (GI) issues. This project aims to examine the relationship between these health and reproductive issues and the captive elephant gut microbiome. To assess the elephant gut microbiome, we leveraged fecal samples and health records from a large Elephant Welfare Project conducted across North American zoos in 2012. Fecal microbiomes of 69 African and 48 Asian elephants from 50 zoos were characterized using Illumina sequencing of the 16S rRNA bacterial gene. Alpha and beta diversity of gut microbiomes were assessed in respect to species, zoo, fertility status, obesity, and frequency of GI issues during the study period.
Results/Conclusions
We found the gut microbiome between captive African and Asian elephants differed in species richness and phylogenetic diversity (alpha diversity), as well as microbial composition (beta diversity: with species explaining 10.2% of variation). Asian elephants had greater species richness and phylogenetic diversity than African elephants. Microbial composition was strongly influenced by the zoo institution and explained 75.8% and 74.2% variation in African and Asian elephants respectively. African elephants at different zoos had different bacterial richness and phylogenetic diversity, while Asians did not vary across zoos. The greater bacterial richness and phylogenetic diversity in Asian elephants and the consistency across zoos suggests the Asian gut microbiome may be more stable in captivity compared to African elephants. There were no differences in bacterial richness, phylogenetic diversity, or overall composition in relation to fertility status, obesity levels or frequency of GI issues. We are currently analyzing the data to identify indicator species linked to these conditions. The strong influence of zoo on the gut microbiome highlights the importance of the environment in shaping the gut microbiome. Our results provide an insight into how captive elephant gut microbiomes are influenced by host species, zoo institution, and health issues.