Trophic ecomorphology of Siluriformes (Pisces, Osteichthyes) from a tropical stream

Abstract

The present study analysed the relationship between morphology and trophic structure of Siluriformes (Pisces, Osteichthyes) from the Caracu Stream (22º 45' S and 53º 15' W), a tributary of the Paraná River (Brazil). Sampling was carried out at three sites using electrofishing, and two species of Loricariidae and four of Heptapteridae were obtained. A cluster analysis revealed the presence of three trophic guilds (detritivores, insectivores and omnivores). Principal components analysis demonstrated the segregation of two ecomorphotypes: at one extreme there were the detritivores (Loricariidae) with morphological structures that are fundamental in allowing them to fix themselves to substrates characterised by rushing torrents, thus permitting them to graze on the detritus and organic materials encrusted on the substrate; at the other extreme of the gradient there were the insectivores and omnivores (Heptapteridae), with morphological characteristics that promote superior performance in the exploitation of structurally complex habitats with low current velocity, colonised by insects and plants. Canonical discriminant analysis revealed an ecomorphological divergence between insectivores, which have morphological structures that permit them to capture prey in small spaces among rocks, and omnivores, which have a more compressed body and tend to explore food items deposited in marginal backwater zones. Mantel tests showed that trophic structure was significantly related to the body shape of a species, independently of the phylogenetic history, indicating that, in this case, there was an ecomorphotype for each trophic guild. Therefore, the present study demonstrated that the Siluriformes of the Caracu Stream were ecomorphologically structured and that morphology can be applied as an additional tool in predicting the trophic structure of this group.

Ecomorphology and use of food resources: inter- and intraspecific relationships of fish fauna associated with macrophyte stands

“…The main goal of ecomorphology is to understand the response of organisms to environmental challenges, by comparing patterns of variations in morphological and ecological characters (Motta et al, 1995). Ecomorphological analysis can be used to describe patterns along niche dimensions, since the body shape provides relevant information about the use of resources by organisms (Bourke et al, 1997;Fugi et al, 2001;Pagotto et al, 2009Pagotto et al, , 2011Oliveira et al, 2010;Sampaio et al, 2013). For example: the depressed and elongated body of armored catfishes (Siluriformes: Loricariidae) permits a more efficient occupation of the bottom in lotic habitats, since this adaptation compensates the difficulties caused by the current, eliminating the effect of drag forces that tend to elevate their body .…”

“…Thus, morphological patterns in assemblages tend to characterize species groups that explore the same ecological resource -e.g., species in the same trophic guild may present a higher morphological similarity, independently of their phylogenetic distance , since the exploitation of specific food items in an ecosystem can be facilitated by a specific design (Wootton, 1992;Norton & Brainerd, 1993;Gerking, 1994;Norton, 1995;Winemiller, et al, 1995;Montaña & Winemiller, 2009;Sampaio et al, 2013). For this reason, some authors attribute to the morphology the ability to predict the ecological niche -i.e., how the body shape selects the ecological space in a given habitat, and consider that ecomorphology can be used as a tool in analysis of assemblage structure (Winemiller, 1991;Casatti & Castro, 2006;Oliveira et al, 2010;Pagotto et al, 2011). On the other hand, since fish diets are diverse (using all available food resources in the environment), it is reasonable to question whether there are general patterns of use of prey and whether these patterns are related to the diversity of feeding mechanisms (Wainwright, 1999).…”

Diet and ecomorphological relationships of an endemic, species-poor fish assemblage in a stream in the Iguaçu National Park

“…If such associations gain phylogenetic support, i.e., if phylogenetically unrelated species exhibit convergence and related species exhibit morphological divergences, the hypothesis gains considerable power of inference (Wainwright & Reilly, 1994). Several studies have shown consistent relationships between morphology and feeding habits (Pouilly et al, 2003;Oliveira et al, 2010;Pagotto et al, 2011;Mise et al, 2013), demonstrating different predictive models of community structure (Casatti & Castro, 2006;Oliveira et al, 2010).…”

Intraspecific ecomorphological variations in Poecilia reticulata (Actinopterygii, Cyprinodontiformes): comparing populations of distinct environments

“…Therefore, aware of the limitations of this approach, but at the same time, considering it an important alternative in the attempt to express the ecology of the species, in the present study ecomorphological indexes were calculated combining the morphological measures and areas: compression index; depression index; relative length, height and width of the caudal peduncle; relative length, height and width of the head; vertical eye position, relative area of the eye and fins (dorsal, anal, caudal, pectoral and pelvic). The indexes were selected according to Gatz (1979), Winemiller (1991), Mazzoni et al (2010), Oliveira et al (2010), and Pagotto et al (2011).…”

“…Despite the difficulties aforementioned, recent studies have shown that there is a significant relationship between morphological variations and ecological aspects, such as feeding and habitat occupation (e.g. Teixeira & Bennemann, 2007;Oliveira et al, 2010;Pagotto et al, 2011;Santos et al, 2011). From these studies, the interspecific morphological variation seems to have an important role in the ecological aspects, favoring the ecological diversification of the species, providing niche differentiation and, consequently, the coexistence of the species.…”