Theoretical Ecology | Community Ecology & Biodiversity
Partilha de nicho em comunidades de girinos de ambientes lênticos (Niche partitioning in a pond community of tadpoles)
Diogo Borges Provete*, Denise de C Rossa-Feres, Itamar A Martins
*Corresponding author: Diogo Borges Provete
Departamento Zoologia e Botânica, PPG Biologia Animal, UNESP, Campus Sâo José do Rio Preteo, São Paulo, Brazil
Departamento Ecologia, Laboratório Ecologiade Insetos, Universidade Federal de Goiás, Goiás, Brazil
F1000Posters 2011, 2: 1344 (poster) [ENGLISH]
Poster [1.39 MB]
63a Reunião Anual da Sociedade Brasileira para o Progresso da Ciência (63rd Annual Meeting of the Society for the Advancement of Science) 2011, 10 - 15 Jul 2011, 137
Sociedade Brasileira para o Progresso da Ciência
One approach often used by ecologists to understand how a wide variety of species can co-exist locally is to study how they use available resources. The key assumption of these studies is that resources are limited and organisms compete for them. Previous studies of resources partitioning in animal communities, including tadpoles have shown that the main niche dimensions that explain species coexistence are habitat, time and food. As a result, the coexistence is possible when species differ in the use of at least one of these dimensions. Our goal was to determine the degree of niche overlap in the three main niche axes.
This study was conducted in the plateau of the Serra da Bocaina National Park, São José do Barreiro, São Paulo. We sampled 13 ponds with different morphologies and hydroperiods. Each water body was sampled once a month between July 2008 and June 2009. We sampled tadpoles with a wire mesh passed along the margin of water bodies. We fixed tadpoles in the field with 10% formalin. For the analysis of niche overlap, we considered the months of the year in which tadpoles occurred as the time axis, the occurrence in the ponds as the spatial axis and the diet items as the food niche axis. To analyze the tadpoles diet, we took a sample from the first centimetre of the gut of five tadpoles of each species between stages 35 and 38 that occurred between December 2008 and January 2009, the peak of abundance for most species. The content were removed and homogenized in 160μL of transeau solution and then we took a sub-sample 40μL to mount microscope slides. We built null models to each niche axis separately in the “niche overlap” module of EcoSim software. We used the RA3 randomization algorithm for analysis and spatial and food niche and the RA4 for temporal niche. We used the Czekanowski index to measure niche overlap.
We recorded 11 species of tadpoles during the study period. The diet of tadpoles was composed of 52 items, including plankton microalgae and periphyton, CPOM, cladocerans, protozoa, fungi and fragments of arthropods. The most consumed items were diatoms and the algae Gonyaulax, the items less frequent were algae of the genera Golenkinia, Phytelios and Pleurotaenium. The null models for the temporal and spatial axis showed that overlap in these axes was not significant. In addition, we found that the overlap in the food was significantly greater than expected from the null model. This suggests that tadpoles usually consume the same food items, but differ in the spatial and temporal axes. The role of resource partitioning in tadpole communities is not consensual, and the use differential microhabitat is often suggested as a secondary way of partitioning food resources. On the other hand, species may have taken advantage of the large influx of primary production in ponds during the rainy season, so these resources may not actually be limited.
Gradients of hydroperiod and canopy cover may have influenced the spatial distribution of tadpoles, contributing to the partitioning of these dimensions. The analysis showed that species were generalists in relation to diet composition, and seemed to consume the available resources indiscriminately.
No relevant conflicts of interest declared.
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