The coexistence of endemic species of Astyanax(Teleostei: Characidae) is propitiated by ecomorphological and trophic variations

Abstract

The coexistence of endemic species of Astyanax (Teleostei: Characidae) is propitiated by ecomorphological and trophic variations. Biota Neotrop. 13(3): http://www.biotaneotropica.org.br/v13n3/en/abstract?article+bn00513032013Abstract: The aim of the present study was to evaluate factors that may favor the coexistence of three endemic species of Astyanax (Astyanax bifasciatus, Astyanax minor and Astyanax gymnodontus ) in Segredo Reservoir (Iguaçu River, Paraná State, Brazil), and to test the hypothesis that these species share food resources, being the dietary variations related to morphological characteristics. Fish were collected at three samplings sites in 1993 and 1994, during the first year after the filling phase of the reservoir. The diet was assessed using stomach content analysis and ecomorphology by ecomorphological indices. Diet and ecomorphology data were ordinated by multivariate techniques (DCA and PCA, respectively), aiming to characterize trophic guilds and identify ecomorphological patterns. A MRPP was performed to check differences between diet and morphology of species. Trophic and ecomorphological patterns were recorded among the Astyanax species, and significant differences were found for both aspects. In this way, our results corroborate the presupposed hypothesis. Therefore, the trophic and ecomorphological segregation between Astyanax species from Segredo Reservoir can contribute to reduce the competition, favoring thus their coexistence. Resumo: O objetivo deste estudo foi avaliar os fatores que favorecem a coexistência de três espécies endêmicas de Astyanax (Astyanax bifasciatus, Astyanax minor e Astyanax gymnodontus) no reservatório de Segredo (rio Iguaçu, Paraná, Brasil), e testar a hipótese de que as três espécies partilham os recursos alimentares, sendo que as variações na dieta estão relacionadas às características morfológicas das espécies. Os peixes foram coletados em três estações de amostragem no primeiro ano após o fechamento da barragem, nos anos de 1993 e 1994. A dieta foi avaliada através da análise dos conteúdos estomacais, e a ecomorfologia através dos índices ecomorfológicos. Os dados de dieta e morfologia foram ordenados por meio de técnicas multivariadas (DCA e PCA, respectivamente), com a finalidade de caracterizar as guildas tróficas e identificar os padrões ecomorfológicos. Posteriormente, foi realizada uma MRPP para verificar a existência de diferenças quanto à alimentação e os padrões morfológicos entre as espécies. Padrões tróficos e ecomorfológicos foram registrados entre as espécies de Astyanax. Diferenças significativas foram encontradas para ambos os aspectos. Dessa forma, os resultados corroboraram a hipótese inicial, sendo a segregação trófica e ecomorfológica entre as espécies deAstyanax do reservatório de Segredo um fator que pode contribuir para diminuir a competição entre elas, favorecendo a sua coexistência no ambiente. Palavras-chave: peixe, partilha de recursos, divergência ecomorfológica, Rio Iguaçu, reservatório de Segredo.

Trophic specialization and morphological divergence between two sympatric species in Lake Catemaco, Mexico

“…This study confirmed that Astyanax species are an opportunistic group (Mise et al., ) with the ability to exploit a wide variety of trophic resources; however, some important differences were found between the two coexisting species studied here. For example, δ 15 N and δ 13 C showed wider variation in A. aeneus (Figure ), which has been suggested as a characteristic of fish with omnivorous habits in lacustrine systems (Córdova‐Tapia, Contreras, & Zambrano, ; Jepsen & Winemiller, ; Vander Zanden & Vadeboncoeur, ).…”

“…In characiforms, previous studies have found correlations between ecomorphological traits and trophic ecology, which can help us to understand the factors that enable the coexistence of closely related species (Bonato et al., ; Mise et al., ). The present study corroborated the occurrence of a significant correlation between ecomorphological traits and trophic habits (i.e., stable isotopes values) of two sympatric species of Astyanax genus.…”

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

“…If such associations gain phylogenetic support, i.e., if phylogenetically unrelated species exhibit convergence and related species exhibit morphological divergences, the hypothesis gains considerable power of inference (Wainwright & Reilly, 1994). Several studies have shown consistent relationships between morphology and feeding habits (Pouilly et al, 2003;Oliveira et al, 2010;Pagotto et al, 2011;Mise et al, 2013), demonstrating different predictive models of community structure (Casatti & Castro, 2006;Oliveira et al, 2010).…”

The Effects of Rapid Water Level Changes on Fish Assemblages: The Case of a Spillway Gate Collapse in a Neotropical Reservoir

“…Small‐sized, pelagic, opportunistic, with generalist habits and moving in shoals ( Astyanax spp. ; Cassemiro et al ., ; Loureiro‐Crippa and Hahn, ; Mise et al ., ), as much as benthic species, with narrower feeding habits, that occupy lentic stretches ( Glanidium ribeiroi ; Pimelodus britskii ; Reis et al ., ), large‐bodied species, which lives near to the substrate, rarely organized in shoals ( Hypostomus commersoni ; Reis et al ., ) and also exclusive fish‐eating predators ( Oligosarcus longirostris ; Gealh and Hahn, ), showed an increase in abundance after the water level variation.…”