Competition between males improves resilience against climate change
Animal species with males who compete intensively for mates might be more resilient to the effects of climate change, according to research by Queen Mary University of London.
Moths exposed to increasing temperatures were found to produce more eggs and have better offspring survival when the population had more males competing for mating opportunities (three males for every female).
The study, published in the journal Proceedings of the Royal Society B, suggests that sexual selection can provide a buffer against climate change and increase adaptation rates within a changing environment. This could improve understanding of how changing environments might affect animal species in both natural and agricultural systems.
PhD student and lead author Jon Parrett from Queen Mary's School of Biological and Chemical Sciences said: "Climate change is altering environments all over the world in a variety of ways, with increases in temperature of several degrees being likely in many places. It is vitally important that we understand how animal populations will respond to these changing environments. Our study is the first to look at how sexual selection affects an animal population's ability to respond to gradual increases in temperature."
"We found that moths were more likely to succeed in stressful environments of increasing temperature when there were more males competing for mating opportunities. This is because males who were best adapted to the new environment were more likely to be mated with, and these successful fathers passed on their 'good genes' to their offspring, aiding survival in the new environment."
Several populations of the Indian meal moth Plodia interpunctella were established with either a male-biased sex ratio of three males for every female (strong competition) or a female-biased sex ratio of one male for every three females (weak competition). The team then gradually increased the temperature that they were reared at by 2°C every other generation.
As temperature increased beyond the normal range for these animals, populations showed declines in the number of eggs produced per female and also in the survival of offspring to adulthood.
The populations kept with a male-biased sex ratio, however, were more resilient to increasing temperatures. Production of offspring and survival rates were still affected, but significantly less than in the female-biased populations.
The team extended the study by comparing females who were allowed to choose their mates with females who were only given a single option of a male to mate with. They found that when females were allowed to be choosy they also laid more eggs and had better offspring survival in the face of increasing temperatures.
These positive effects of sexual selection may, however, be too small to protect populations and delay extinction when environmental changes are relatively rapid.
Co-author Dr Rob Knell from Queen Mary's School of Biological and Chemical Sciences said: "We used a laboratory system for this research, but our conclusions are likely to be applicable to many animal species. Intense competition for mates is a feature of many well-known animals: rutting stags, displaying peacocks, male birds of paradise and singing male crickets are all trying to win the mating game.
"Our results indicate that these competitive mating systems can play an important role in determining the response to new environments, whereas species where there is less competition for mates are likely to be less able to adapt to new conditions."
The authors caution that the study is only a laboratory demonstration of the effect and more research is needed to fully understand how these effects might operate in natural systems.
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Notes to the editor
Research paper: Parrett JM, Knell RJ. 2018. The effect of sexual selection on adaptation and extinction under increasing temperatures. Proc. R. Soc. B 20180303.
Available here after the embargo lifts: http://dx.doi.org/10.1098/rspb.2018.0303
About Queen Mary University of London
Queen Mary University of London is one of the UK's leading universities with 25,332 students representing more than 160 nationalities.
A member of the Russell Group, we work across the humanities and social sciences, medicine and dentistry, and science and engineering, with inspirational teaching directly informed by our research. In the most recent national assessment of the quality of research, we were placed ninth in the UK amongst multi-faculty universities (Research Excellence Framework 2014).
As well as our main site at Mile End – which is home to one of the largest self-contained residential campuses in London – we have campuses at Whitechapel, Charterhouse Square, and West Smithfield dedicated to the study of medicine and dentistry, and a base for legal studies at Lincoln's Inn Fields.
Queen Mary began life as the People's Palace, a Victorian philanthropic project designed to bring culture, recreation and education to the people of the East End. We also have roots in Westfield College, one of the first colleges to provide higher education to women; St Bartholomew's Hospital, one of the first public hospitals in Europe; and The London, one of England's first medical schools.