Figure 2: Mean (±SE) of copulation frequency among B. treatae individuals from their own host-associated population or the alternative host-plant-associated population when host plants were absent or present. Sexual isolation is indicated by a difference between copulation frequency when paired with an individual from the “same” host plant population versus a “different” host plant population. The additional effect of habitat isolation is indicated by a shift in the magnitude of the difference between same and different host pairings when the host plant is present during the mating assay. Numbers above the SEs are the number of replicates.