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Predation, Breeding Asynchrony, and the Outcome of Competition Among Treefrog Tadpoles
Author(s) -
Morin Peter Jay
Publication year - 1987
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938473
Subject(s) - hyla , biology , crucifer , interspecific competition , predation , ecology , intraspecific competition , competition (biology) , metamorphosis , tadpole (physics) , hylidae , amphibian , predator , hatchling , larva , zoology , botany , hatching , physics , particle physics
Densities of a predatory salamander (0, 2, or 4 Notophthalmus viridescens/m 3 ) and a spring—breeding frog tadpole (100, 200, or 400 Hayla crucifer/m 3 ), were controlled in a 3 x 3 factorial experiment replicated three times in 27 artificial ponds. Shortly before all Hyla crucifer metamorphosed from the ponds, 200 hatchlings of a summer—breeding frog, Hyla versicolor, were added to each artificial pond. Differences among ponds in growth and survival of H. versicolor provided a bioassay for the effects of predators and previously established competitors. Increased predator density decreased the survival and increased the mean mass at metamorphosis of H. versicolor, regardless of H. crucifer density. Increased H. crucifer density decreased the survival and mass at metamorphosis of H. versicolor in ponds without predators. Increased H. crucifer density decreased the mass at metamorphosis of H. versicolor adjusted for variation among ponds in the density of surviving H. versicolor, over all artificial ponds. Total H. versicolor biomass was negatively correlated with the biomass of H. crucifer metamorphs, in artificial ponds without predators. This experiment demonstrates strong competition between two species of asynchronously breeding treefrogs in predator—free ponds, and thereby compromises the traditional assumption of weak interspecific competition among temporally separated species. However, predation greatly reduces the intensity of competitive interactions among asynchronously breeding species.