How deciphering the reproductive microbiomes can contribute to the conservation of wild mammalian species – A review

The study of microbiomes has significantly advanced, revealing their profound influence on host health and reproduction. Despite progress in human and domestic animal research, a substantial knowledge gap persists regarding reproductive microbiomes in wild mammals, particularly their impact on fertility and gamete viability. Characterizing these microbial communities is crucial for developing effective conservation strategies. This narrative review focuses on current research about reproductive microbiomes in wild mammals, detailing identification techniques (16S rRNA gene sequencing, MALDI-TOF MS) and distinguishing "microbiome" from "microbiota." It examines reproductive microbiota in both genders, including semino-vaginal interactions, highlighting their roles in reproductive health and drawing from cross-species comparisons. The review also addresses critical research gaps, such as the functional roles of specific microbial taxa, host-microbe specificity, longitudinal dynamics, and limited data on male reproductive health in species like elephants and marine mammals. Furthermore, this work explores microbiome-based diagnostics and treatments (e.g., probiotics, microbiota transfers) to improve reproductive outcomes and mitigate threats like dysbiosis. We also acknowledge unique logistical and ethical challenges in wild species sampling and manipulation, including contamination and inter-individual variability. By integrating these insights, the review offers a novel, microbial perspective for preserving wildlife and fostering healthier wild populations.