Drosophila mate copying correlates with atmospheric pressure in a speed learning situation

Mate choice can strongly affect fitness in sexually reproducing organisms. A form of mate choice is mate copying, in which individuals use information about potential mates by copying the mate choice of other individuals. While many studies have documented mate copying, little is known about the effect of environmental conditions on this behaviour. Here, we report the first evidence that Drosophila melanogaster females can acquire a sexual preference for one male characteristic after witnessing a single mate choice event (i.e. speed learning). We also found that mate copying was correlated with air pressure and air pressure changes, so that females copied far more when air pressure was high and increasing, i.e. in good and improving weather conditions. These results reveal a quick social observational learning and highlight the potential importance of meteorological conditions for mate copying, a trait potentially driving reproductive isolation.