New research from the University of East Anglia has shown that females can maximise the genetic quality of their offspring by being promiscuous.
Researchers studied red junglefowl (the wild ancestor of the domestic chicken) in a collaborative project with the University of Oxford, Stockholm University and Linköping University.
Findings published today in the journal Proceedings of the Royal Society B reveal that mating with different males helps females produce offspring that are more resistant to diseases. The findings will be important for animal breeders as well as conservation projects because they show that allowing multiple matings will produce the most disease resistant and genetically healthy offspring.
This is down to 'cryptic female choice' - where 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 infections. By biasing fertilisation in favour of MHC-dissimilar males, females increase the diversity of MHC within their offspring, providing them with better disease resistance.
The findings will be important for animal breeders as well as conservation projects because they show that allowing multiple matings will produce the most disease-resistant and genetically-healthy offspring.
Prof David S Richardson, from UEA's school of Biological Sciences, said: "Our research has shown that the females don't need to choose between males to produce the most healthy offspring. Rather by mating with multiple males, they allow their internal choice mechanism to favour the most genetically different sperm."
The research investigated both experimentally controlled natural matings and artificial inseminations and found that the effect observed in natural matings was lost during artificial insemination.
Prof Richardson added: "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.
"Many breeding programmes for livestock and conservation use artificial insemination. But our research suggests that this may not produce the best quality offspring.
"This is because the effect appears to require the subconscious female assessment of the male by some cue during actual mating.
"So having correct cues during mating, perhaps the smell of the male, can affect a females' chances of being fertilised. And the 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."
The research was funded by BBSRC, the Natural Environmental Research Council (NERC), Stockholm University, the Schwartz' foundation, Lars Hierta's foundation, Knut & Alice Wallenberg's foundation, the Royal Swedish Academy of Science, and the Royal Swedish Academy of Agriculture and Forestry.
'Cryptic female choice favours sperm from MHC-dissimilar males' by H Løvlie, MAF Gillingham, K Worley, T Pizzari, and DS Richardson is published in the journal Proceedings of the Royal Society B on September 4, 2013.
Notes to editors
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About the UEA
The University of East Anglia (UEA) was founded in 1963 and this year celebrates its 50th anniversary. It has played a significant role in advancing human understanding and in 2012 the Times Higher Education ranked UEA as one of the 10 best universities in the world under 50 years of age. The university has graduated more than 100,000 students, attracted to Norwich Research Park some of Britain's key research institutes and a major University Hospital, and made a powerful cultural, social and economic impact on the region. www.uea.ac.uk/50years
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The Natural Environment Research Council (NERC) is the UK's main agency for funding and managing world-class research, training and knowledge exchange in the environmental sciences. It coordinates some of the world's most exciting research projects, tackling major issues such as climate change, environmental influences on human health, the genetic make-up of life on earth, and much more. NERC receives around £320 million a year from the government's science budget, which it uses to fund independent research and training in universities and its own research centres. www.uea.ac.uk/biological-sciences
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