Semen adaptation to microbes in an insect.

Area of Science:

• Evolutionary biology
• Reproductive science
• Microbiology

Background:

• Sperm function is influenced by sexual selection and microbial damage.
• The evolutionary adaptation of sperm to microbes remains under-explored.

Purpose of the Study:

• To investigate experimental evidence of male fertility adaptation to microbes.
• To understand the impact of coevolutionary history between males and female microbes on fertility.
• To examine the role of female immune activation and sperm storage in modulating microbial effects on sperm.

Main Methods:

• Experimental manipulation of male-sperm-microbe interactions in vivo.
• Comparison of male fertility in scenarios with coevolved versus non-coevolved microbes.
• Assessment of female immune system activation and sperm storage timing effects.

Main Results:

• Male fertility decreased by approximately 20% when sperm encountered novel microbes compared to coevolved ones.
• Female immune system activation further reduced male fertility by an additional 13%.
• Non-coevolved males showed increased fertility when microbes were introduced post-sperm storage, suggesting a protective role for female sperm storage.

Conclusions:

• Male fertility demonstrates adaptive capacity to microbial environments, contingent on evolutionary history.
• Female reproductive tract microbes and immune responses significantly modulate male fertility.
• Female sperm storage may offer a previously unrecognized benefit of microbial protection, influencing reproductive outcomes and potentially speciation.