Niche enlargement as a consequence of co-existence: a case study

R Mazzoni,Cf Rezende,R Iglesias-Rios,Ps Marques

doi:10.1590/s1519-69842012000200006

R Mazzoni, Cf Rezende + Show 2 more

Open Access

https://doi.org/10.1590/s1519-69842012000200006

Copy DOI

Abstract

Spatio-temporal changes in the diet, niche breadth and niche overlap of two species of Characidium from three different sites along a Neotropical coastal stream were studied during a dry and rainy season. Seasonal changes were restricted to the occurrence of plant items in the stomach contents. The relative importance of food items in the diet of both species varied across sites, but Diptera, Ephemeroptera, Simuliidae, Trichoptera and Coleoptera larvae were always the main prey items. Contrary to the expected pattern, values of the niche breadth were higher at the site where Characidium species co-existed and niche overlapped at this site indicated 52% (p = 0.52) of feeding overlap.

Highlights

The idea that competition is an important mechanism in the organization of populations and communities has been considered the cornerstone of ecological and evolutionary theory
We studied the spatio-temporal variation in the feeding habits of two close-related characins: Characidium interruptum (Pellegrin, 1909) and Characidium cf. vidali (Travassos, 1967) from a Neotropical stream
Environmental parameters were very similar for each sampling site (Table 1) and no significant differences (H = 1.91; p = 0.39) in prey availability were found between them (Table 2)

Summary

Introduction

The idea that competition is an important mechanism in the organization of populations and communities has been considered the cornerstone of ecological and evolutionary theory. Since Hutchinson (1957) questioned the mechanisms that allow sympatric species to partition resources and co-exist, it has been noted that in highly diverse communities, realized niches and niche breadth are reduced as a consequence of competition (Mac-Arthur, 1972). Tropical communities support higher diversity than temperate ones, and according to the resource partitioning theory one would expect a more specialist species. The intensity of competition is traditionally estimated using some measure of similarity or overlap in the resources used by co-occurring species (Pusey and Bradshaw, 1996), but the observed patterns vary among environments and/or climatic regions (Zaret and Rand, 1971). The absence of competition in tropical regions has often been attributed to resource partitioning

Methods

Results

Conclusion