But actually they’re the authors of a cute little paper on the mating habits of long tailed dance flies where, unusually, the traditional roles are reversed and guys pick out their mates from a ‘swarm’ of lovely ladies showing off their wares.
Winning over a girl with dinner and dancing seems fairly common. Although finding her in a ‘meat market’ style club full of ladies with their guts puffed out (literally) to attract the opposite sex seems a little far fetched. But this is precisely what the long tailed dance fly Rahamphomyia longicauda does.
Night after night you’ll find her chilling out under the same patch of sky. A male, clutching his gift of dinner, sees her wide silhouette against the light and the gift is handed over. A spot of privacy is found – the evenings task completed, she’ll be back tomorrow for another go.
But why? you might ask…. Well i’ll tell you
While the dance flies are hunting insects, feeding on midges and whatever other tasty critters they can catch, but the females of the species have lost the ability to hunt and rely males to get enough food to survive and reproduce.
So guys have all the power, and come to meet the gathering girls in their patches of light with food items to exchange for sex. Having gone through all the trouble to hunt down a snack it’s in his best interests to choose the ‘best’ female. But who’s the best female? The guys are under the mistaken impression that bigger females have bigger eggs which are therefore more likely to be fathered by him/ and able to survive to hatching so in their eyes bigger = better.
Males wear the pants in this situation, controlling the food supply – so have the power to choose who might give him the best children. To deal with this power imbalance females puff themselves up to look like they have bigger eggs.
So as long as the guys can’t tell the difference, bigger really is better.
In response to this selective pressure females have evolved some secondary sexual characters to make herself look bigger – they line their legs along the margin of the abdomen and her leg hairs are ‘designed’ to make her look even wider., and puff their guts out into special pockets along the abdomen to make her even bigger.
But heres the puzzle
Bigger girls might not have better eggs,
but they get more sex,
and with that comes food because males bring ‘nuptial gifts’,
so they will produce better eggs
So the best strategy for a male is still to choose the biggest female,
and the cycle continues.
Perhaps the real question is who’s tricking who?
So girls: puff out you gut, be a wide load for a night, if you’re a long tailed dance fly it might just pay off.
Animal behavior paper, 2000, Courtship role reversal and deceptive signals in the long tailed dance fly.
Sofie A Welvaert 
