Temporal and spatial variation in newt (Notophthalmus viridescens) response to non-injured and injured conspecifics.

摘要

I examined red-spotted newt, Notophthalmus viridescens, responses to chemicals from injured conspecifics (alarm chemicals thought to signal foraging predators) and non-injured conspecifics at various temporal scales. During the breeding season, female odor accelerated male recovery from antipredator responses induced by alarm chemicals, such that male response depended on time after treatment exposure. As mate search activity and male attraction to females increased during the breeding season, male avoidance of conspecific alarm chemicals declined, but alarm chemical production appeared unchanged. Thawing dates differed between bordering subpopulations and between populations, which offset levels of mate search activity and consequently alarm chemical avoidance. As a result, simultaneously examining these sites made it appear as though there was significant geographic variation in newt activity and response to alarm chemical. However, upon aligning site thawing dates, activity and behavior across sites became strikingly similar, indicating that temporal variation can easily be mistaken for spatial variation.; While males during the breeding season were attracted to both sexes, and on average did not avoid alarm chemical, females during the breeding season were indifferent to conspecifics of both sexes, and only avoided injured females. During the non-breeding season, both males and females were indifferent to conspecifics and avoided injured conspecifics, but the magnitude of male avoidance was almost significantly greater than female avoidance, suggesting sex differences in both the breeding and non-breeding seasons.; When examining responses across ontogeny, recently-hatched predator-naïve and predator-experienced larvae decreased activity in response to odor from adults (frequent cannibals of larvae), but these larvae did not possess alarm chemicals. Adults and efts (terrestrial juveniles) were indifferent to non-injured, but avoided injured adults and efts in moist environments. Under dry conditions, efts were attracted to conspecific odors, which facilitated huddling and reduced evaporative water loss, but did not avoid injured conspecifics. Attraction to conspecifics in dry conditions likely compromised alarm chemical avoidance. Time in ontogeny, in a year, in a season, and after exposure to a predation stimulus all affected newt antipredator behavior emphasizing their extreme plasticity, but more importantly, the risks of misinterpreting biological systems if various temporal scales are not considered.