Global Ecology and Conservation (Apr 2024)
Does habitat matter in avoiding predators among sympatric Katydid species?
Abstract
Natural selection, through eavesdropping predators, plays a crucial role in shaping katydid behavior. Predators use the conspicuous katydid calls for prey localization. While commonly deployed defenses are known for many katydids, the possible effects of habitat and sex are not explored. We studied predator evasion among six sympatric katydid species from two habitats namely, grasslands (Conocephalus maculatus, Euconocephalus pallidus, Euconocephalus helleri) and forest understorey (Ducetia assamica, Ducetia rohinii and Mecopoda elongata). We observed passive defense strategy (perch height, habitat choice and crypsis) of katydids in the field. We tested avoidance behavior through two sets of treatment: (a) physical disturbance, where individuals were exposed to increasing intensity of perch disturbance, and (b) acoustic playback, in which individuals were exposed to social and foraging calls of a sympatric bat species. We tested the null hypothesis that predator avoidance is similar between species in different habitats and between sexes. Only grassland species, C. maculatus and E. pallidus exhibited significant differences in passive defense between sexes. There were no significant differences in avoidance behavior between sexes in any species for predatory cues. GLM models depicted a significant effect of sex on the choice of perching height in three of the four species. Body size had a significant effect on passive defenses in all four species tested for physical disturbance. For the largest species, M. elongata body size affected both the passive and active defenses. When compared between ecosystems, the grassland-dwelling species (E. helleri) was more sensitive to physical disturbance, while understorey species (D. assamica) was found to be more sensitive to the acoustic cues. We propose that habitat plays a determining role in the evolution of avoidance behavior.
