Diet Relationship and Its Role in the Coexistence of Two Species of Annual Fishes
Ecology of Freshwater Fish 2015: 24: 77–90 Ó 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd ECOLOGY OF FRESHWATER FISH The morphology–diet relationship and its role in the coexistence of two species of annual fishes Friedrich W. Keppeler1,2, Luis Esteban K. Lanes 2,3, Ana S. Rolon2, Cristina Stenert2, Pablo Lehmann4, Martin Reichard5, Leonardo Maltchik2 1Department of Ecology, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul (RS) Brazil 2Laboratory of Ecology and Conservation of Aquatic Ecosystems, University of Vale do Rio dos Sinos (UNISINOS), S~ao Leopoldo, RS Brazil 3Laboratory of Ichthyology, Instituto Pro-Pampa (IPPampa), Pelotas, RS Brazil 4Laboratory of Ichthyology, University of Vale do Rio dos Sinos (UNISINOS), S~ao Leopoldo, RS Brazil 5Academy of Sciences of the Czech Republic, Institute of Vertebrate Biology, Brno, Czech Republic Accepted for publication January 10, 2014 Abstract – Annual fishes, which inhabit temporary pools with extremely limited habitat complexity and niche availability, display remarkable sexual dimorphism, rapid growth, and enormous investment into reproduction, all traits associated with high energy requirement. This study tests three hypotheses for two syntopic annual fishes (Austrolebias minuano and Cynopoecilus fulgens) found in six wetlands of southern Brazil: (i) considerable morphological differences result in low dietary overlap, (ii) sexual dimorphism in both species leads to intraspecific diet segregation, and (iii) dietary richness increases during ontogenetic development, and is narrower in C. fulgens than A. minuano due to morphological limitations imposed by reduced size. The diet of 82 A. minuano and 211 C. fulgens individuals was analyzed over two annual cycles.
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