16 November 2015
How to pull the birds: whether you’re territorial, a girlfriend stealer or a cross dresser, it’s in your genes
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.”
21 May 2008
New genetic map to reveal secrets of our garden birds
Researchers from the University of Sheffield will be able to unravel the genetic secrets of many of our favourite garden birds, after producing the world´s first genomic linkage map of the Zebra Finch bird.
The Zebra Finch is a model organism for behavioural ecologists and neurobiologists. By identifying the genes in a model organism it will now be possible to see if the same genes have similar effects in other birds and organisms, including humans.
The map will help researchers understand the genes responsible for many birds´ amazing diversity of colourful plumage, elaborate song and remarkable behaviours that have long fascinated biologists and ornithologists alike. Published in the journal Genetics the map is an important part of a larger global project to sequence the Zebra Finch genome and represents the only involvement of a UK institution.
The map is a vital tool because it shows which chromosome particular genes lie in, similar to the methods used by medical geneticists to identify disease genes in humans. The main use of the map will be to provide researchers with the tools necessary to find the genes responsible for individual differences in traits such as plumage, song, learning and memory, and even sperm mobility.
To produce the map the researchers studied three generations of Zebra Finch, which belongs to a group of birds called the Passerines. Comprising over 6,000 species this group of birds bring the sound of spring to gardens all over Europe and include garden birds such as the Blue Tit, Blackbird, Thrush and Robin.
Dr Jon Slate, a senior lecturer in the University´s Department of Animal and Plant Sciences at the University, who worked on the study, said: "Mapping the Zebra Finch genome is tremendously exciting for several reasons. First, it provides far greater understanding into how bird genomes have evolved over the last 100 million years. For example, we now know that bird genomes are not as evolutionarily conserved as was once thought.
"Second, the map will be a great resource to researchers all over the world. The Zebra Finch is a model organism in several biological disciplines and the map provides the resource to find the genes responsible for variation in bird characteristics. It is very likely that genes discovered in this species will have similar effects in humans as well."
Notes to Editors:
The research `A Linkage Map of the Zebra Finch Taeniopygia guttata Provides New Insights Into Avian Genome Evolution´ has been published online in Genetics – For more information visit the website.
The research has been funded by the Biotechnology and Biological Sciences Research Council (BBSRC). For more information visit the webpage.
16 August 2007
Females avoid incest by causing male relatives to leave home
Researchers at the University of Sheffield in the UK and Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, Germany, have found that female hyenas avoid inbreeding with their male relatives by giving them little choice but to leave their birth group.
Animals generally avoid inbreeding because it is genetically hazardous. They can either do this by moving away from home or, like humans, by learning who their relatives are and not mating with them.
Like most mammals though, male hyenas do not contribute to the rearing of their offspring, making it highly unlikely that females know who their father is. Instead males decide to leave the group in which they were raised, resulting in a low level of inbreeding.
But until now, little was known about why the males and not the females decided to move away from home. The new research on spotted hyenas, published in Nature this week, shows that the reason most males move from their natal group is because of female mate-choice – the rules females use when choosing which of the many male group members will sire their offspring.
The researchers found that young females prefer to mate with `new arrivals´ in a group - those males born into, or who joined, the group after the female was born. Older females also apply this rule and in addition prefer males that have built friendly relationships with them for several years. These mate preferences of females mean that males have to choose groups with a high number of young females if they want to reproduce successfully.
The research showed that males usually chose groups with the highest number of young females, giving them access to many females and enabling them to sire a higher number of offspring in the long term. Most males end up dispersing because a higher number of young females usually occurs elsewhere, rather than in the group in which they were raised.
Professor Burke, from the Department of Animal and Plant Sciences at the University of Sheffield, said: "This is the first time a study has shown that in mammal species the system is driven by females using very simple rules to avoid breeding incestuously."
Dr Oliver Höner from the IZW added: "The results of the study were only possible because we were able to monitor the decisions made by male hyenas in all eight resident hyena groups on the floor of the Ngorongoro Crater. Through this research we could genetically determine paternity for most offspring produced in a 10-year monitoring period."
Notes to editors:
The research has been published in Nature magazine.