Wild Animal Reproductive Microbiomes (EvolSWARM)

Our view of microbes has recently undergone a paradigm shift (the so-called ‘microbiome revolution’). Previously seen as unwanted harbingers of disease, it is now widely recognised that microbes can be beneficial and that the millions of microbes living in and on the bodies of animals and plants (i.e., the microbiome) can have profound effects on host biology. However, with the exception of the human vaginal microbiome, the microbiome revolution has largely overlooked the reproductive microbiome. This is especially true for wild animals. Yet, if we are to understand the evolutionary significance of host-associated microbiomes it is critical to study them in natural populations, where hosts exhibit greater genetic variability and are exposed to greater levels of environmental and microbial complexity.

The aim of this project is to determine whether reproductive microbiomes impact host fitness and evolution in wild animals, and reveal the role of host genetics and immune functioning in shaping reproductive microbiome variability.

Working with wild house sparrows in both natural populations and captive aviaries, our project has four major aims:

• We will identify links between natural variation in the reproductive microbiome and fitness in a wild population of house sparrows on Lundy Island (UK).
• We will experimentally test the effect of variation in reproductive microbiome composition to reproductive success using novel in vivo microbiome transplant techniques. 
• We will investigate the role of genetics in shaping variation in the reproductive microbiome.
• We will investigate the potential for host control of the ejaculate microbiome in male house sparrows and determine whether the reproductive microbiome influences sperm quality. 

Altogether, this project will significantly advance our understanding of the causes and – more importantly – the consequences of reproductive microbiomes for host biology and evolution.