Eco‐morphological attributes and feeding habits in coexisting characins

Abstract

The head morphology and feeding habits of pairs of characin species (family Characidae) that coexist in four different coastal rainforest streams were analysed. Coexisting species differed in size, but were very similar in eco-morphological attributes. Gut analyses revealed differences in feeding preferences for each coexisting species, indicating resource partitioning. A pattern of organization in species pairs that was repeated in the four studied streams was noticed. The pattern consisted of one slightly larger species with a feeding preference for items of allochthonous origin and another smaller species with a preference for autochthonous items. The hypothesis that small morphological differences enable the current coexistence of those species pairs was proposed. Furthermore, the results show ecological equivalence among different species in the studied streams.

Morphological traits correlated with resource partitioning among small characin fish species coexisting in a Neotropical river

“…Notably, all studied species were capable of active and accelerated swimming (Casatti & Castro, 2006; Portella et al, 2017). However, differences in body depth and caudal peduncle length may confer differential advantages in the exploration of differing compartments when they are co‐occurring.…”

“…In all species examined, versatility in locomotory patterns permitted them to use both generalised and specialised feeding modes on a fairly wide variety of resources (from invertebrates to vegetal materials). Within the limits of their habitat, characins seem to be able to exploit all types of available resources, giving these fish exceedingly generalist trophic ranks (Dala‐Corte, Becker, & Melo, 2017; Delariva et al, 2013; Manna, Rezende, & Mazzoni, 2012; Pini et al, 2019; Portella et al, 2017; Silva et al, 2017). However, under conditions of species coexistence we found that resource partitioning occurred on finer scales.…”

“…In addition, fish of the family Characidae exhibit many diverse trophic modes (Hyatt, 1979). The genera Astyanax and Bryconamericus (“lambaris”; genera incertae sedis in Characidae) (Lima et al, 2003) form one of the fish clades most abundant in which dietary plasticity has been particularly well documented by previous studies (Bonato, Burress, Fialho, & Armbruster, 2018; Delariva, Hahn, & Kashiwaqui, 2013; Kokubun, Bonato, Burress, & Fialho, 2018; Oricolli & Bennemann, 2006; Pini et al, 2019; Portella, Lobón‐Cerviá, Manna, Bergallo, & Mazzoni, 2017; Silva, Gubiani, Neves, & Delariva, 2017) and has also been associated with the exploitation of alternative and seasonally varying resources in tropical systems (Neves et al, 2018; Silva, Gubiani, & Delariva, 2014).…”

Trophic morphology features allow Astyanax endemic species coexistence in a Neotropical river system

“…These morphologic specializations can be a result of the high genetic diversity of this group as well as a result of different environmental pressures (Costa-Pereira et al, 2016;Matoso et al, 2004;Nishiyama et al, 2016;Peres et al, 2005). In some places, Astyanax species coexist through resource partitioning, with adaptations in size and mouth position, teeth morphology and eye diameter (EDI) (Bonato et al, 2017;Portella et al, 2017;Santos et al, 2011). Garavello & Sampaio, 2010, Astyanax gymnodontus Eigenmann, 1911, and Astyanax bifasciatus Garavello & Sampaio, 2010 are endemic species of the Iguaçu River basin and coexist in different water bodies from this basin (Baumgartner et al 2012), such as rivers and reservoirs (Pereira & Agostinho, 2019;Pini et al, 2019).…”

“…These morphologic specializations can be a result of the high genetic diversity of this group as well as a result of different environmental pressures (Costa‐Pereira et al ., 2016; Matoso et al ., 2004; Nishiyama et al ., 2016; Peres et al ., 2005). In some places, Astyanax species coexist through resource partitioning, with adaptations in size and mouth position, teeth morphology and eye diameter (EDI) (Bonato et al ., 2017; Portella et al ., 2017; Santos et al ., 2011).…”