Sequential Analysis Reveals Behavioral Differences Underlying Female-Biased Predation Risk in Stalk-Eyed Flies

Abstract

Stalk-eyed flies are classic models of how sexual selection can drive morphological and behavioral elaboration. Exaggerated ornaments born by stalk-eyed flies could impose locomotor costs and increase susceptibility to predation; however, a previous study determined that behavior, not eye span, was the major influence on predation risk. Despite the importance of behavior, relatively little is known about how these flies avoid and deter predators. We created an ethogram of behaviors and used it to score individual interactions of male and female Teleopsis dalmanni paired with an actively foraging, generalist arachnid predator (Phidippus audax). Sequential analysis was employed to identify temporal patterns in behavior and determine how males and females differ in their approaches to avoiding predation. Our results indicate that males and females significantly differ when specific behaviors were employed. Patterns in the behavioral transitions suggest that males are more aggressive than females and are more likely to approach a predator to jab, abdomen bob, or display. Males elicited more retreat responses from the predator, whereas females elicited more attacks. Although the behavioral repertoires of male and female stalk-eyed flies are indistinguishable, their uses of the behaviors differ, particularly the sequential order of presentation, suggesting a strong sex difference in anti-predatory behavior.