Time line of experiment. Ozonated and control flies are exposed for 2h to 100 ppb and 5 ppb of ozone, respectively. Afterwards, individual female flies are confronted with one intra- and one interspecific male for six hours. The existence or absence of hybrid offspring informs about the succeeding male. Donut plots of success rates of ozonated (top) and control (bottom) conspecific and allospecific males courting D. melanogaster ( b ), D. mauritiana ( c ), D. simulans ( d ), or D. sechellia ( e ) females. Sample sizes are provided in donut centers. Numbers in segments depict numbers of successful males. White segments, no male mated the female. Red donuts depict significant increase of hybridization after exposure to high levels of ozone. Two-tailed Fisher's exact test, * p < 0.05; ** p < 0.01; *** p < 0.001.
