Flies to give new insight into mating rituals

Wednesday 14 February 2001

A study of one of the world’s most common flies could improve the understanding of mating behaviour throughout the animal world.

Mike Ritchie and Leon Hockham from the University of St Andrews’ School of Biology have been awarded a grant to study Empid flies which display such a range of diverse mating techniques that they will give a fresh insight into a range of different birds, insects and animals.

The Empid fly, of which there are thousands of species throughout the world and 100 species in the UK alone, are mainly found in the UK, North America and Scandinavia. The project, the only one of its kind in the UK, will involve scientists examining the DNA of several species, recording their behavioural data and investigating which factors different mating techniques are associated with. Ultimately, the project will reveal the Empid flies’ “family history.”

Empid flies take part in a wide range of bizarre mating techniques including courtship feeding where males supply dead flies to females for them to eat during copulation and often present symbolic gifts such as silken balloons (sometimes containing prey and sometimes empty). Other species show signs of sex reversal where females compete for males, and females have secondary sexual traits such as swollen abdomens aimed at fooling males into thinking they are full of ripe eggs. In other species, males attract females by displaying pretend dead pray which are, in reality, merely growths on male legs.

The evolution of nuptial gifts is thought to be a classic case of ritualisation in courtship behaviour but Mike and Leon believe the answer may lie in sexual conflict between males and females with confidence of paternity driving variation in the effort males or females put into courtship behaviour.

Mike said, “This research has important implications for the entire animal world. Most courtship displays are thought to emphasise how valuable or well- adapted an individual is. For example, the elaborate tail of the peacock is thought to advertise how good that males’ genes are. However, in Empid flies, we apparently see deception and cheating occuring frequently. What has allowed this manipulation to occur and are sham courtship meals a male trying it on, or a response to infidelity in females? Ultimately, this research will tell us about the evolution of courtship rituals which are now known to be one of the major causes of speciation in animals. Cheating and counter-strategies may explain just why they evolve so quickly.”

The work is collaborative with Derby University and the British Museum of Natural History.


Issued by Beattie Media on behalf of the University of St Andrews For more information please contact Claire Grainger on 01334 462530, 07730 415 015 or email [email protected] Ref: flies/standrews/chg/13feb2001

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