A trade-off between antipredatory behavior and pairing competition produced by male-male tandem running in three Reticulitermes species

Due to the omnipresent risk of predation, termites have evolved many antipreda- tory behaviors. The two related species Reticulitermes speratus and R. chinensis have been demonstrated to use homosexual tandem running to decrease individual predation risk after shedding their wings. In this study, we tested risk of predation in the termite R. flaviceps, which is distantly related to the above two species. We determined that homosexual tandem running also led to low individual predation risk in dealates of R. flaviceps. Moreover, by combining a predation model with a competition model, we observed a typical trade-off phenomenon between antipredatory behavior and pairing competition produced by male- male tandem running in the above three Reticulitermes species. Our results indicated that male-male tandem running could effectively protect disadvantaged individuals from being caught, but disadvantaged individuals would be easily eliminated in pairing competition after male-male tandem running, suggesting that male-male tandem running can pro- mote population evolution in termites by repeatedly removing the relatively inferior male individuals.

Ecological significance of dorsal polymorphism in a Batesian mimic snake

Batesian mimicry is the process in which harmless species adopt the appearance of a dangerous, aposematic species.In some prey species,both Batesian mimetic and non-Batesian morphs coexist,presupposing that both morphs have to be evolutionarily advantageous.The viperine snake, Natrix maura,exhibits a zigzag dorsal pattern and antipredatory behavior that mimics European vipers.This snake also has a striped dorsal pattern that coexists with the zigzag pattern.We have examined whether individuals belonging to different geographically structured clades were more likely to exhibit a certain dorsal pattern,and whether the zigzag pattern has a protective function by exposing artificial snakes to predation in natural environments,in addition to comparing antipredatory behavior between zigzag and striped snakes also in natural environments.Our results indicate that the striped pattern was not geographically structured,but habitat-dependent.Aerial predators less frequently attacked zigzag plasticine models than striped or unpatterned models.We detected a shift in antipredator behavior between the 2 morphs,as Batesian mimicking N.maura responded to an approaching potential predator by remaining immobile or fleeing at shorter distances than did striped ones.We conclude that Batesian mimics maintain the cryptic and aposematic value by resembling vipers,whereas in open habitats the non-Batesian mimic has altered its antipredator behavior to maintain its fitness.

Predator-prey distance and latency to flee from an immobile predator： functional relationship and importance

When an immobile prey has detected an immobile predator nearby, predation risk is greater when the predator is closer. Consequently, prey flee with shorter latency as standing distance （predator-prey distance when both are still） decreases. Since it was first reported in 2009, this relationship has been confirmed in the few species studied. However, little is known about the functional relationship between standing distance and latency to flee （LF）. We hypothesized that LF increases as standing distance increases at short distances, but reaches a plateau at longer distances where prey can escape reliably if attacked. We simulated immobile predators by moving slowly into positions near striped plateau lizards Sceloporus virgatus, stopping and then remaining immobile, and recording LF from the stopping time. LF increased from shorter to longer standing distances in a decelerating manner. The relationship was concave downward, and LF was indistinguishable among the longer standing distance groups. Latency to flee appears to reach a plateau or approach an asymptotic value as stand- ing distance increases. The effect size of standing distance was large, indicating that S. virgatus sensi- tively adjusts LF to the level of risk associated with standing distance. Relationships between risk assessment and theoretical zones associated with risk, its assessment by prey, and escape decisions are discussed. Effect sizes of standing distance were substantial to large in all studies to date, indicating that standing distance is an important predation risk factor when both predator and prey are immobile.