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

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.Keywords: neotropical characidae, coastal stream, close related species. Ampliação do nicho como consequência da co-existência: um estudo de caso ResumoVariações espaço-temporal na dieta, na amplitude e na sobreposição de nicho foram estudadas para duas espécies de Characidium de três localidades distintas de um riacho costeiro da região Neotropical, considerando-se as estações seca e chuvosa. As alterações sazonais na dieta foram restritas à presença/ausência de itens vegetais nos conteúdos estomacais. A importância relativa dos itens alimentares, de ambas as espécies, variou entre as localidades de estudo; porém, as larvas de Diptera, Ephemeroptera, Simuliidae, Trichoptera e Coleoptera foram sempre as presas mais consumidas. Em oposição ao padrão esperado, os valores de amplitude de nicho foram maiores na localidade em que as duas espécies de Characidium ocorreram em sintopia e a sobreposição de nicho, nessa localidade, indicou 52% (p = 0,52) de sobreposição alimentar.Palavras-chave: characidae neotropical, riachos costeiros, espécies relacionadas.

Diet and ecomorphological relationships of an endemic, species-poor fish assemblage in a stream in the Iguaçu National Park

“…For streams with higher species richness, the diet breadth has also been found to be low (Wolff et al, 2013;Winemiller et al, 2008). These patterns and the results found here suggest that dietary specialization may not necessarily be linked only to interspecific competition or to the availability of resources (Esteves & Lobón-Cerviá, 2001;Mazzoni et al, 2012;Vitule et al, 2013).…”

Comparative feeding ecology of four syntopic Hypostomus species in a Brazilian southeastern river

“…Differences of feeding tactics may lead during the evolutionary history of the species to a reduction of the effect for alimentary overlapping (Sabino and Correa e Castro, 1990). By considering that species belonging to a same genus use to show similarities in their general characters, Mazzoni et al (2012) suppose that other characteristics which were not measured or perceived in this study may help to explain this feeding patterns and species coexistence.…”

Diet of two syntopic species of Crenuchidae (Ostariophysi: Characiformes) in an Amazonian rocky stream

“…Meanwhile, high feeding overlap has been extensively registered between closely related species, and the spatial segregation (e.g., meso or microhabitats) was considered as the most important partitioning mechanism (Schoener 1974, Aranha et al 1998, Aranha et al 2000, Mazzoni et al 2012, Silva et al 2012, Leitão et al 2015, Barros et al 2017.In Amazonian streams, high dietary overlap (60%) was registered between syntopic characids (Bryconops inpai and B. giacopinii), but they were occupying distinct positions in the water column (Barros et al 2017). Furthermore, competition between species with similar dietary habits would also be reduced by the high amount of preys found in this same area (Knoppel 1970).…”