The competition-colonization tradeoff hypothesis predicts that good colonizers are poor competitors. The Blanchard’s cricket frog (Acris blanchardi) is an effective colonizer of young ponds in wetland habitats, but this species faces range contractions. Previous studies suggest that green frogs (Lithobates clamitans) can outcompete cricket frogs and decrease their survival to metamorphosis. This study examined interactions between these anurans over a leaf litter gradient in which lower leaf litter quantities may represent younger ponds. Both species were reared in outdoor mesocosms with 0.25kg or 1.0kg of leaf litter. We manipulated six tadpole community types including tadpole-free controls, 25 cricket frogs, 50 cricket frogs, 25 green frogs, 50 green frogs, and 25 of both species in a mixed community. Leaf litter quantity, rather than community structure, had the greatest impact on the development of both anurans and the aquatic community. High leaf litter treatments corresponded with larger masses and quicker development, on average. Cricket frogs showed a trend of lower total survival in high density communities regardless of competitor identity. Green frogs had greater masses in high density mixed communities than high density green frog communities, suggesting that they were facilitated by the presence of cricket frogs. Periphyton and phytoplankton became more abundant in high leaf litter treatments than low leaf litter treatments over time. Although differences in leaf litter quantity affected the availability of algal resources, cricket frogs did not obtain an advantage in low leaf litter environments. Therefore, the interactions between the two anuran species in this study did not support the competition-colonization tradeoff hypothesis.
Author(s): Hannah Bey and Michelle D. Boone, PhD
Advisor(s): Michelle D. Boone, Biology Department
You must be logged in to post a comment.