Newswise — Whether you're territorial, a girlfriend stealer, or a cross dresser - when it comes to finding a partner, scientists have discovered that for some birds it's all in the genes.
Individual animals usually exhibit flexibility in their behaviour, but some behaviours are genetically determined.
Using genome sequencing, researchers from the University of Sheffield have now identified the genes that determine the striking mating behaviour of the males of a wading bird known as the ruff.
The ruff has a 'lek' mating system, which means males of the species gather together and invest all of their energy into attracting females to mate with them, and none into parental care.
Within this specific mating system three distinct breeding behaviour types are easily identifiable.
• Territorial breeding males have spectacular plumes around their neck (which is why these birds are called ruffs) and head, and vary enormously in colouration so that each male is distinguishable.
• Nonterritorial so-called 'satellite' males, which are distinguishable by their white feathers, concentrate on stealing mates from the territorial displaying males.
• A third type of male, which is thought of as a 'cross-dresser', mimics females. They are able to hide from other males in the lek, so avoiding territorial aggression, and succeed by effectively stealing mates from the resident males.
The new study, by an international team including researchers from the University of Sheffield, Simon Fraser University (Canada), and the University of Edinburgh, published today in Nature Genetics, shows that the three distinct breeding behaviour types are encoded by a 'supergene' - a section of a chromosome containing a hundred or more genes.
This supergene was created several million years ago by a chromosomal rearrangement, which originally allowed the female mimic to evolve and coexist with the territorial males.
Lead author of the study, Professor Terry Burke from the University's Department of Animal and Plant Sciences, said: "The special feature of the supergene is that it allows lots of genes that are next to each other on a chromosome - which in this case determine multiple traits including hormones, feathering, colour and size - to evolve together and create two distinct behavioural traits.
"This process is similar to the one that led to the evolution of separate sex chromosomes, and indeed the alternative forms of the supergene combined together to create the third type of bird personality - the girlfriend stealer.
"The ruffs provide a neat example of how small genetic changes can lead to major differences in attractiveness and behaviour. This process is fundamental to the formation of separate sexes and separate species."
He added: "Unlike young men at a social occasion who have each chosen a different approach to courtship, whether that's showing off or paying a compliment, for these birds there is no choice in the matter. It's their DNA that dictates how they win a partner."
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Notes to Editors
University of Sheffield
With almost 26,000 of the brightest students from around 120 countries, learning alongside over 1,200 of the best academics from across the globe, the University of Sheffield is one of the world's leading universities. A member of the UK's prestigious Russell Group of leading research-led institutions, Sheffield offers world-class teaching and research excellence across a wide range of disciplines. Unified by the power of discovery and understanding, staff and students at the university are committed to finding new ways to transform the world we live in. In 2014 it was voted the number one university in the UK for Student Experience by Times Higher Education and in the last decade has won four Queen's Anniversary Prizes in recognition of the outstanding contribution to the United Kingdom's intellectual, economic, cultural and social life. Sheffield has five Nobel Prize winners among former staff and students and its alumni go on to hold positions of great responsibility and influence all over the world, making significant contributions in their chosen fields. Global research partners and clients include Boeing, Rolls-Royce, Unilever, AstraZeneca, Glaxo SmithKline, Siemens and Airbus, as well as many UK and overseas government agencies and charitable foundations.
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