Testing the ecomorphological hypothesis in a headwater riffles fish assemblage of the rio São Francisco, southeastern Brazil

Author(s)

Casatti, Lilian ^[1] ; Castro, Ricardo M. C. ^[2]

Affiliation

^[1] Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. Instituto de Biociências, Letras e Ciências Exatas - Brasil

^[2] Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto - Brasil

• Document type: Journal article
• Source: Neotropical Ichthyology; v. 4, n. 2, p. 203-214, Apr.- June 2006.
• Field of knowledge: Biological Sciences - Zoology

Abstract

The ecomorphology of 14 fish species resident in a headwater riffles area of the São Francisco river, southeastern Brasil, was analyzed and combined with diet and feeding behavior data, previously obtained by us. The three larger species groups formed in the ecomorphological analysis were found to reflect primarily microhabitat occupation in the following manner: a) nektonic characids with compressed bodies, lateral eyes and lateral pectoral fins, with diurnal and opportunistic feeding habits (Astyanax rivularis, Bryconamericus stramineus, and Bryconamericus sp.); b) nektobenthic characiforms and siluriforms with fusiform bodies and expanded pectoral fins, including sit-and-wait characidiins, predators of aquatic insect larvae (Characidium fasciatum and Ch. zebra), as well as the algae grazing parodontids (Apareiodon ibitiensis and Parodon hilarii), and also the heptapterid and trichomycterid catfishes that practice substrate speculation and feed on benthic aquatic insect larvae (Cetopsorhamdia iheringi, Imparfinis minutus, Rhamdia quelen, and Trichomycterus sp.); c) benthic species with depressed bodies, suctorial oral discs, dorsal eyes, and horizontal pectoral fins, represented by the periphytivorous loricariid catfishes (Hisonotus sp., Harttia sp., and Hypostomus garmani). Correlation between diet and general morphology was not significant in our analysis, unless when the analyzed set included only nektonic and benthic species, indicating that the lack of correlation between these factors is most pronounced in the group of nektobenthic species. The unequivocal case of morphological convergence found between the nektobenthic Characidiinae and Parodontidae is a clear example of the integration between phylogenetic information and ecomorphology, and provides a way to objectively identify cases of morphological and adaptive convergence and divergence. Furthermore, the general congruence between the ecomorphological results and the independently obtained ecological data about the analyzed fish species in their natural environment seems to be strong evidence in favor of the proposed predictive capabilities of the ecomorphological hypothesis. (AU)

• FAPESP's process: 00/01919-8 - Biology and structure of three communities of fish from the Sete de Setembro tributary, Morro do Diabo State Park, Alto Rio Paraná Basin, SP
• Grantee: Lilian Casatti
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 98/05072-8 - Fish diversity of the headwaters and streams of the Upper Paraná River System in the State of São Paulo, Brazil
• Grantee: Ricardo Macedo Corrêa e Castro
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 01/00602-3 - Phylogenetic relationships of the South-American freshwater Sciaenidae (Perciformes)
• Grantee: Lilian Casatti
• Support Opportunities: Research Grants - Meeting - Abroad
• FAPESP's process: 01/13340-7 - Evaluation of the biotic integrity of the rivers of the northwest region of the State of São Paulo, Alto Paraná basin, using communities of fish
• Grantee: Lilian Casatti
• Support Opportunities: BIOTA-FAPESP Program - Young Investigators Grants