Abstract
Abstract Diet and morphology of Serrapinnus notomelas and Serrapinnus sp.1 were investigated across ontogeny, as a way to elucidate the key elements linked to the resource partitioning (a main driver for species coexistence). Fish sampling was conducted monthly between October 2010 and March 2012. Individuals were captured, identified, and classified into juvenile or adult. Our results show ontogenetic and interspecific differences in feeding abilities and morphological traits. Differences in body shape (relative area of the dorsal fin, length of head, height of the caudal peduncle, the aspect ratio of the pectoral and pelvic fin) favored divergent swimming performances (more maneuverability in S. notomelas and continuous swimming to Serrapinnus sp.1). We also observed divergences in trophic apparatus traits and correlations with different diets. In this context, it is highlighted that understanding the relationship between morphology and diet can assist in elucidating the processes that permeate the coexistence between sympatric species, and between ontogenetic periods. Besides, the relevant contribution of the measures of the trophic apparatus (gill raker length, the number of teeth cuspids, and intestinal coefficient) in trophic segregation seems to be a strong evidence in favor of the proposed discriminatory and predictive capacities of these traits.
Highlights
Macrophyte stands in floodplain areas have been suggested as essential for the biological diversity maintenance, since they provide structurally complex habitats (Agostinho et al, 2007; Dibble, Thomaz, 2009; Yofukuji et al, 2021)
The stomach contents of 121 individuals belonging to two species, S. notomelas and Serrapinnus sp.1, were analyzed (Tab. 1)
Inter and intraspecific differences in diet, trophic niche breadth, and morphological traits confirm the differentiation of trophic niche between the sympatric and congeneric species that we evaluated here
Summary
Macrophyte stands in floodplain areas have been suggested as essential for the biological diversity maintenance, since they provide structurally complex habitats (Agostinho et al, 2007; Dibble, Thomaz, 2009; Yofukuji et al, 2021) These environments offer favorable abiotic conditions such as lower light and temperature, acting as food sources and refuge against predators (Colares et al, 2013; Cunha et al, 2019; Yofukuji et al, 2021). The complexity of the conditions and resources noted in macrophytes acts as robust environmental filters influencing the selection of traits adjusted to the demands of food and shelter over time (Prado et al, 2016; Cunha et al, 2019; Quirino et al, 2021)
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