“…Such variation in body and head shapes of fish populations may be influenced by differences in predation (Burns et al, 2009;Araújo et al, 2014), diet (Hegrenes, 2001), local habit (Langerhans et al, 2003;Sidlauskas et al, 2006;Webster et al, 2011), geomorphology (physical and/or chemical features) or sub-basins (Lowe-McConnell, 1999), and genetic divergence or phenotypic plasticity or a combination of those factors (Svanbäck, Eklöv, 2006;Elmer et al, 2010;Zamudio et al, 2016). Some intraspecific studies on characid species have pointed out that morphological differentiation among populations or groups can be related to environmental, heterochronic, or geographic factors (Román-Valencia et al, 2009;Ornelas-García et al, 2014;Aguirre et al, 2016;Marinho, Langeani, 2016;Vanegas-Ríos, 2016;Lazzarotto et al, 2017).…”