Ecological separation by ecomorphology and swimming performance between two congeneric fish species

Abstract

The high diversity of freshwater fish species reflects a great morphological plasticity. Understanding the relationship between swimming capacity, morphology and habitat use may be important to predict the chances of finding a species at an anthropized environment. The swimming capacity and morphological aspects of two sympatric species of Characidium, and for which spatial segregation in different hydraulic habitats is known, were compared in this study. Twenty-one individuals of Characidium fasciatum Reinhardt, 1867 and 23 individuals of Characidium cf. zebra Eigenmann, 1909 were captured and used for the evaluation of the swimming capacity and ecomorphological attributes. The swimming capacity of each species was obtained by measuring critical and relative velocities. A total of 12 ecomorphological attributes correlated with habitat use and swimming characteristics were also compared. The Mann-Whitney mean test showed that the swimming capacity of C. fasciatum was greater than that of C. cf. zebra, and the standard length of the individuals explained 12.42% of the variation in their capacity to withstand water flow. Both species were morphologically distinct in the relative length of the caudal peduncle, ventral flattening index and the relative area of the pectoral fin. The relative area of the pectoral fin alone accounted for 16.71% of the differences in the ability to resist the water flow and which were not explained by body length. Our results showed that two species differed in the ecomorphological space and in their swimming capacity, supporting the hypothesis that the greater the hydrodynamism, the better a fish is able to withstand the water flow, and that this capacity is correlated with the morphological characteristics linked to the swimming activity of the fish.

Ecomorphology of yellowtail lambari (Characiformes: Characidae) in the neotropical semi-arid region, Brazil

“…Ecomorphology studies the relationship between morphology and ecology of individuals, populations, and communities, analyzing its evolutionary consequences (Gatz, 1979;Winemiller, 1991). Different researchers have used this tool to understand and relate morphological variations and different types of habitats with the biological aspects of the studied species (Bano and Serajuddin, 2021;Soria-Barreto et al, 2019;Souza and Pompeu, 2020). The morphology of organisms and their habitats are entirely correlated, that is, the phenotype of the organism is associated with the characteristics of the environment and indirectly with the available resources, due to environmental and ecological pressures for survival (Gatz, 1979;Howe et al, 2022;Manna et al, 2020;Paz Cardozo et al, 2021).…”

Ecomorphological relations of sympatric juveniles of Clupeiformes from a Brazilian sandy beach

“…Ecomorphology may be an important indicator of species diet and trophic position (Blasina et al, 2016), being able to identify adaptative convergence in phylogenetically distant species, and adaptative divergences in phylogenetically close ones (Reilly & Wainwright, 1994;Cassati & Castro, 2006). It helps classifying the feeding habits associated with linear models, identifying possible changes in species feeding patterns and trophic levels according to the phase of the life cycle and infer about swimming ability (Vorsatz et al, 2019;Souza & Pompeu, 2020;Podder et al, 2021a,b;Santos et al, 2021).…”