Most research has focused on the oral, skin, and gut microbiomes, but bacteria, viruses, and fungi living within our reproductive systems may also affect sperm quality, fertilization, embryo implantation, and other aspects of conception and reproduction. Yet, according to a review published January 14 in the journal Trends in Ecology & Evolution , little is known about the reproductive microbiome.
What we do know is that there are examples of microbes affecting sexual health and fertility across the animal kingdom, and that these impacts seem to have important consequences for reproductive biology and behavior.
"Reproductive microbiomes can have significant effects on the reproductive function and performance of both males and females," says senior author Tommaso Pizzari, a zoologist at the University of Oxford. "These studies also shed light on the role of the reproductive microbiome in sexual selection, mating system, and sexual conflict."
While research has begun to link alterations in the vaginal microbiome to adverse pregnancy outcomes in humans, it's unclear how the male reproductive microbiome affects fertility and reproductive success, says first author Melissah Rowe (@melissah_rowe), an evolutionary ecologist who studies reproductive biology and behavior at the Netherlands Institute of Ecology.
"This is surprising, because research has shown that bacteria can damage sperm form and function, and that damaged sperm can contribute to pregnancy failure" Rowe says.
Many major questions remain. Rowe and Pizzari are intrigued by how some microbes benefit one sex or species while harming another. For example, Lactobacilllus--associated with a healthy vaginal microbiome in women and high-quality semen in men--seems to negatively affect sperm-swimming speed in chickens. But the authors say that the combination of sequencing advances, genomic resources, and investigations of host sexual behavior will likely lead to more discoveries soon.
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This work was supported by the Research Council of Norway.
Trends in Ecology & Evolution , Rowe et al.: "The Reproductive Microbiome: An Emerging Driver of Sexual Selection, Sexual Conflict, Mating Systems, and Reproductive Isolation" https://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(19)30325-8
Trends in Ecology & Evolution ( @Trends_Ecol_Evo ), published by Cell Press, is a monthly review journal that contains polished, concise and readable reviews, opinions and letters in all areas of ecology and evolutionary science. It aims to keep scientists informed of new developments and ideas across the full range of ecology and evolutionary biology--from the pure to the applied, and from molecular to global. Visit: http://www.cell.com/trends/ecology-evolution . To receive Cell Press media alerts, please contact press@cell.com .
Trends in Ecology & Evolution