Reproductive Microbiomes in Wild Animal Species: A New Dimension in Conservation Biology

Communities of microbes have coevolved in animal organisms and are found in almost every part of the body. Compositions of those communities (microbiota) as well as their genomes and genes (microbiomes) are critical for functional regulations of the body organ systems-the digestive or 'gut' microbiome being the most described so far. Based on extensive research in humans, microbiomes in the reproductive tract may play a role in reproductive functions and pregnancy. However, in wild animal species, those microbiomes have been poorly studied, and as a result, little is known about their involvement in fertility or parental/offspring health. This emerging research area is highly relevant to conservation biology from captive breeding management to successful reintroduction or maintenance of wild populations. The objective of this chapter is to review current knowledge about reproductive microbiomes in healthy wild animal species. While recognizing the current technical limits of microbial identification in all animal species, we also explore the link between microbial communities (within female or male reproductive systems) and fertility, from conception to birth outcome. In addition, it is critical to understanding how reproductive microbiomes are affected by environmental factors (including captivity, contact with other individuals, or changes in the ecosystem) to optimize conservation efforts. Thus, reproductive microbiomes represent a novel dimension in conservation biology that will likely gain importance in the future.