Morphological diversity of fish along the rio das Velhas, Minas Gerais, Brazil

Abstract

The rio das Velhas, located in central Minas Gerais State (Brazil), is a major tributary of the rio São Francisco. Despite several anthropogenic pressures, this basin supports more than 115 fish species. The aim of this study was to compare the morphological space occupied by fish assemblages in four regions (headwaters, upper, middle, and lower course) along the channel of the rio das Velhas. We try to answer the following question: Is there a change in the morphological organization of the fish along the longitudinal gradient of the river? Individuals from 67 species, collected at several sites in the basin from 1999 to 2008, were measured for 11 morphological attributes related to swimming behavior and habitat use. Through the graphs, the first two dimensions of the PCA suggest that the morphological volume occupied by the headwaters region is smaller than the other sections, because of the low richness of the site. However, morphological hypervolumes of the four reaches analyzed by Euclidean distances were not statistically different. The results indicated that only the density of morphological types increases along the rio das Velhas, and there is no difference between the headwaters and upper courses. Therefore, in order to use functional groups related to the morphology of the species as tools to take measures for the conservation and revitalization of the rio das Velhas, it is necessary analyze the density of species within these groups, as well as their composition.O rio das Velhas, localizado na região central do estado de Minas Gerais (Brasil), é o mais extenso tributário do rio São Francisco. Apesar dos inúmeros impactos antrópicos que sofre, sua bacia abriga uma rica ictiofauna, com mais de 115 espécies conhecidas. O objetivo deste estudo foi comparar o espaço morfológico ocupado pelas assembleias de peixes em quatro regiões (cabeceira, alto curso, médio curso e baixo curso) ao longo da calha do rio das Velhas. Procuramos responder a seguinte pergunta: há uma mudança na organização morfológica da comunidade de peixes ao longo do gradiente longitudinal do rio? Indivíduos de 67 espécies, coletados em diversos trechos da bacia entre 1999 e 2008, foram medidos considerando 11 atributos morfológicos relacionados ao comportamento natatório e uso do habitat. Graficamente, as duas primeiras dimensões da PCA sugerem que o volume morfológico ocupado pela região de cabeceira é menor do que o dos demais trechos, devido à baixa riqueza do local. Entretanto, os hipervolumes morfológicos dos quatro trechos analisados por meio das distancias euclidianas não diferiram estatisticamente. Os resultados indicaram que apenas a densidade de tipos morfológicos aumenta ao longo do rio das Velhas, sendo que não há diferença entre a cabeceira e o alto curso. Portanto, para o uso de grupos funcionais relacionados à morfologia das espécies como ferramentas para tomada de medidas que visem à conservação e revitalização do rio das Velhas, é necessária a abordagem da densidade de espécies dentro destes grupos, assim como sua compo...

Linking fish ecomorphotypes to food categories and local‐scale habitat uses along a Brazilian coastal stream

“…Benthic traits were correlated to fast‐flowing, rocky habitats, while compressed bodies were associated to slow‐flowing habitats. Like Junqueira et al (2012), who did not find longitudinal differences in the fish morphological types, all body patterns occurred along the Vermelho River. However, in the longitudinal context, changes in hydrological conditions may be exercising larger‐scale filtering on the fish traits of local assemblages (Poff, 1997).…”

“…Neotropical freshwater fishes have often been depicted as the most diverse in the world (Albert et al, 2020), reflecting not only species richness but also the high variation of their morphologies (Junqueira et al, 2012; Willis et al, 2005; Winemiller, 1991). This diversification was evidenced here in a single 3 rd ‐order stream, where fishes presented distinct ecomorphological (EM) patterns.…”

“…Fish species richness and functional structure change along the headwater‐mouth directions (Ibañez et al, 2009; Zhang et al, 2020); however, the longitudinal role of environmental filtering in morphological structuration is unclear. Additionally, functional‐trait diversity seems to increase as a function of an increase in richness (Junqueira et al, 2012; Pease et al, 2012), but the significance of correlations between longitudinal physical–chemical gradients and fish morphology still needs to be elucidated. Nevertheless, an approach to understanding the longitudinal use of habitats is to correlate fish traits with local‐habitat variables and verify if the EM patterns repeat at broader scales from headwaters to mouth reaches.…”

Ecomorphology and Morphological Disparity of Caquetaia Kraussii (Perciformes: Cichlidae) in Colombia

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