Multiple mates improves disease resistance

Being promiscuous may have benefits say researchers who have found mating with different males helps females produce offspring more resistant to disease.

In a collaborative study, researchers from the University of Oxford, University of East Anglia, Stockholm University and Linköping University studied the red junglefowl – an ancestor of the domestic chicken – finding that multiple copulations will produce the most disease resistant and genetically healthy offspring.

“Our research has shown that the females don’t need to choose between males to produce the most healthy offspring. Rather mating with multiple males, they allow their internal choice mechanism to favour the most genetically different sperm,” said Professor David S Richardson of UAE.

In this cryptic female choice, an internal mechanism in their reproductive tract favours the sperm from males that are most genetically different to them. The genes in question – Major Histocompatibility Complex (MHC) play a key role in detecting and fighting infection. By biasing fertilisation in favour of MHC-dissimilar males, females increase the diversity of MHC in offspring, providing them with better disease resistance.

The research – published in Proceedings of the Royal Society B – investigated both experimentally controlled mating and artificial inseminations, finding the effect observed in natural mating was absent in artificial inseminations.

“To optimise the quality of offspring produced in breeding programs we may need to make sure that females mate with multiple males and that they avoid artificial insemination, which could lead to the genetic health of bred stocks being weaker,” said Richardson.

The research many have important implications for animal breeders and conservation projects, many of which use artificial insemination. This research suggests this may not produce the best offspring because the effect requires the subconscious female assessment of some cue during mating.

“Having the correct cues during mating, perhaps the smell of the male, can affect a females’ chances of being fertilised,” said Richardson. “And cues from different males may not work equally well on different females. This is something that needs to be explored further in various animals including humans.”

Cryptic female choice favour sperm from MHC-dissimilar males http://rspb.royalsocietypublishing.org/content/280/1769/20131296.full