Ontogenetic and individual diet variation in amphibian larvae across an environmental gradient

摘要: Summary 1. Variation among individuals within size or age classes can have profound effects on community dynamics and food-web structure. We investigated the potential influence of habitat disturbance intrapopulation niche variation. 2. Amphibians occupy a range lentic habitats from short-hydroperiod intermittent ponds to long-hydroperiod permanent ponds. quantified ontogenetic diet variation individual specialisation in wood frog tadpoles (Lithobates sylvaticus) blue-spotted salamander larvae (Ambystoma laterale) investigate hydroperiod population width across natural gradient using stable isotope gut content analyses. In one few tests larval forms, we tested hypothesis, which predicts that populations with larger widths also increased variation. 3. Our results support indicating more generalised exhibit higher within-individual variation. report gradual changes relative importance items, decreased dietary overlap trophic position L. sylvaticus throughout development. A. laterale became enriched δ13C δ15N its period. did not find relationship between parameters, niches are conserved heterogeneous habitats. contrast most documented cases, estimated low levels amphibian larvae. 4. Amphibians an important link aquatic terrestrial ecosystems, whereby shifts structure by altering energy flow pathways consumers, ultimately changing food-chain length.