Variation in Predator Phenology Affects Predator Performance and Prey Community Composition

摘要: Variation in predator phenology strongly influenced the performance of four species anuran larvae experimental temporary ponds, composition assemblage metamorphs from those and reproductive predator. The resolution variance by a statistical model these communities was greatly improved when incorporated phenological variation. These results suggest that predictive power more general models interactions could be incorporating size— or stage—specific effects. contained larval Rana utricularia, Scaphiopus holbrooki, Bufo americanus, Hyla chrysoscelis. Dates introduction to ponds corresponded with their breeding nature. predators were adult broken—striped newts (Notophthalms viridescens dorsalis). experiment 2 x 4 factorial design:two levels initial density (1 x) crossed predation regimes (predators absent; initially present removed after 9 d; 51 always present). predator—removal treatments simulated variability observed timing departure natural pond. At both densities, competition interacted determining metamorph assemblage. contribution greater at high than low. Competition among did not fall into simple hierarchy, but formed complex network presence during first weeks period any reduced number species. Predator removal few species' periods affect final abundance, indicating they reached body sizes vulnerability predation. Later anurans benefited before reproduced, reducing earlier When exposed newt predation, performed better throughout summer later reproduced. early had decreased time late removal. Presence past this them competitive effects breeders. A community included absence explained 47% variation explicitly considered 76%, leaving less half as much unexplained. success affected own larvae. Longer residence increased numbers offspring while decreasing mean mass. There strong correlational evidence masses limited density. also emerging ponds. Newt responded which temporal overlap.