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  • Ordinary Animals and the genetics of being sexy

    By Jack Ashby, on 9 November 2017

    The Grant Museum’s current exhibition – The Museum of Ordinary Animals: The Boring Beasts that Changed the World ­­- explores the mundane creatures in our everyday lives. Here on the blog, we will be delving into some of the stories featured in the exhibition with the UCL researchers who helped put it together.

    Guest post by Professor Judith Mank (UCL Genetics, Evolution and Environment)

    Dominant males have all the things that turkey hens want, including long snoods and vibrant wattles. Subordinate males are by comparison rather plain. (Photo by Lupin on Wikimedia. CC BY-SA 3.0)

    Dominant males have all the things that turkey hens want, including long snoods and vibrant wattles.
    (Photo by Lupin on Wikimedia. CC BY-SA 3.0)

    In all species, some individuals are simply better looking than others, and they have the right shape, colour or attitude that makes them irresistible to the opposite sex of their species. Scientists have generally assumed that good looks come primarily from good genes, but this presents an enigma: if only individuals with the best genes pass them on in every generation, those sexy genes should spread and soon the entire population should be equally attractive.

    So… how is that unattractive genes persist in populations? Why doesn’t evolution wipe them out?

    In turkeys, male come in one of two varieties. Dominant males have all the things that turkey hens want, including long snoods and brightly coloured wattles. Subordinate males are by comparison rather plain, and females don’t give them the time of day.

    How can brothers that share 50% of their DNA look so different? It had to be more than just good genes. With a team of researchers at UCL and Oxford, we compared gene expression – which genes were switched on, and which were switched off – between related male turkeys, and found it wasn’t the genes that that mattered, rather how the males used them.

    Dominant males had noticeably more masculine genes “switched on”, with high expression levels of genes primarily expressed in males, and lower expression levels of genes expressed primarily in females.

    The subordinate males, on the other hand, had a more feminine expression pattern. We think that these expression levels may be related to hormone levels: because they are hormonally controlled, this allows males that were once subordinate to take over the dominant role if an opportunity arises. In turkeys at least, it seems that attractiveness is a matter of flipping a genetic switch.

     

    The Museum of Ordinary Animals runs until 22nd December. A number of events accompany the exhibition: through discussions, a late opening, a comedy night and offsite events discover how boring beasts shape our relationship with the natural world. Full details are on the exhibition’s website.

    Judith Mank is Professor of Evolutionary and Comparative Biology at UCL, and contributed to the Museum of Ordinary Animals.

     

    References:

    Pointer MA, Harrison PW, Wright AE, Mank JE (2013) Masculinization of Gene Expression Is Associated with Exaggeration of Male Sexual Dimorphism. PLoS Genet 9(8): e1003697. doi:10.1371/journal.pgen.1003697

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