MICHAELIDIS, C.I.; DEMARY, K.; LEWIS, S.M.; Swarthmore College, Pennsylvania; Tufts University, Medford, Massachusetts; Tufts University, Medford, Massachusetts: Variation in male signaling and female preference in Photinus greeni fireflies

In Photinus fireflies, flying males emit bioluminescent advertisement flashes to which conspecific females selectively respond. Previous work has examined variation in male signals and female preferences in firefly species with either multiple-pulse or single-pulse male signals. However, little is known for Photinus species such as P. greeni in which males emit paired pulses. We examined variation in flash characteristics of P. greeni males by field video recording and found significant among-male variation in inter-pulse intervals (IPI). IPI ranged from 0.73 to 3.10 s with a mean of 1.49 s. To investigate seasonal changes in flash preferences, females were collected throughout the six-week mating season. In lab, we tested their responsiveness to simulated male flashes that differed in pulse duration and IPI. Throughout the mating season, females preferentially responded to simulated flash patterns having shorter pulse durations. However, they were less responsive to all pulse durations later in the mating season. Females preferentially responded to 1 s IPI flashes throughout the mating season, with no seasonal change in overall responsiveness. In the field, we tested female responsiveness at different times of night. We found that females were more responsive after the male flight period when the operational sex ratio (OSR) became female-biased. These data demonstrate considerable variation in both male P. greeni advertisement signals and female responsiveness and suggest that female responsiveness may be affected by mating history and environmental cues associated with changes in the OSR. These results also suggest that females could use different male signal characteristics for mate quality assessment and species recognition.