There is a specific gene tied to deer mouse’s sperm speed, which one day might help a possible genetic influence on male fertility in humans. The deer mouse has a gene that makes its sperm faster and more virile then the field mouse. The reason is that there is an expanded midsection in the sperm’s tail that drives the male mouse’s semen-laden package through the female reproductive tract faster. A gene called PrKar1a is plentiful in the tail’s midpiece, signifying the protein acts as a significant part in midpiece role. Competition among deer mice in mating has driven that species to have a higher level of PrKar1a gene activity, and consequently faster, more competitive sperm. Male fertility in humans may one day be influenced by the addition of the PrKar1a protein to expand the midpiece and increase speed.
https://www.linkedin.com/pulse/mice-might-help-male-fertility-humans-randy-bilesky?published=t
http://www.delta-optimist.com/opinion/blogs/blog-mice-might-help-male-fertility-in-humans-1.2367478