We quantified the strength of assortative mating when variation in the perception of the environment was manipulated experimentally. We manipulated the olfactory neurons of two groups of Drosophila melanogaster which changed their perception of their environment. In response to light (invisible to the flies), one group was designed to smell food (a positive stimulus), while the other group was designed to smell a dangerously high concentration of CO2 (a negative stimulus). We combined both groups of flies, exposed them to a lit habitat and another habitat that was not, and allowed them to choose between these. We then measured the degree of assortative mating between the two types of flies due to any spatial population structure induced by the flies themselves. To control for any assortative mating due to other reasons, we also measured assortative mating when the heterogeneity of the environment could not be perceived by the flies, and when the environment was actually homogeneous.

"psi_data.Rda" contains the raw data and associated sexual isolation indices. "figures.R" is an R script that loads this data and produces two figures that show the effect of the differential perception of the environment on sexual isolation.