Relationships between morphology, diet and spatial distribution: testing the effects of intra and interspecific morphological variations on the patterns of resource use in two Neotropical Cichlids

Abstract

Considering the morphology, diet and spatial distribution of Satanoperca pappaterra and Crenicichla britskii (Perciformes: Cichlidae) in the Upper Paraná River floodplain (Brazil), the following questions were investigated: (1) Could the body shape predict the use of trophic resources and habitat by C. britskii and S. pappaterra? (2) Could the relationship between morphology and use of trophic resources and habitat be also extended to the intraspecific scale? (3) What are the most important morphological traits used to predict the variation on diet and habitat occupation within and between species? We hypothesized that intra and interspecific differences in morphological patterns imply in different forms of resource exploitation and that the ecomorphological analysis enables the identification of trophic and spatial niche segregation. Fish samplings were performed in different types of habitats (rivers, secondary channels, connected and disconnected lagoons) in the Upper Paraná River floodplain. Analyses of the stomach content was conducted to characterize the feeding patterns and twenty-two ecomorphological indices were calculated from linear morphological measurements and areas. A principal component analysis (PCA) run with these indices evidenced the formation of two significant axes, revealing in the axis 1 an ecomorphological ordination according to the type of habitat, regardless the species. The individuals of both species exploiting lotic habitats tended to have morphological traits that enable rapid progressive and retrograde movements, braking and continuous swimming, whereas individuals found in lentic and semi-lotic habitats presented morphology adapted to a greater maneuverability and stabilization in deflections. On the other hand the axis 2 evidenced a segregation related to the feeding ecology, between S. pappaterra and C. britskii. The relationship between morphology and use of spatial and feeding resource was corroborated by the Mantel test performed at inter and intraspecific levels. Therefore the hypothesis was accepted suggesting that analyses incorporating both intraspecific and interspecific morphological variations can contribute to a greater understanding about the ecological structure of fish assemblages by providing evidences on the niche characteristics of each species.Considerando a morfologia, a dieta e a distribuição espacial de Satanoperca pappaterra e Crenicichla britskii (Perciformes: Cichlidae) na planície de inundação do alto rio Paraná (Brasil) as seguintes questões foram investigadas: (1) A forma do corpo pode ser utilizada para predizer o uso dos recursos espaciais e tróficos por ambas as espécies? (2) As relações entre morfologia e uso dos recursos tróficos e espaciais podem ser estendidas à escala intraespecífica? (3) Quais são as características morfológicas utilizadas para predizer a variação na dieta e ocupação do hábitat em nível intra e interespecífico? Testou-se a hipótese de que diferenças intra e interespecíficas nos padrões morfológicos implicam em diferentes for...

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

“…Thus, the utilization of indices minimize the chances of the analysis be dominated by a single variable (Winemiller, 1991). Studies using indices were performed by other authors (Gatz, 1979;Watson & Balon, 1984;Montaña & Winemiller, 2010;Sampaio et al, 2013). Higher values indicate lateral compression of the fish, expected for fish that exploit habitats with slower water velocity (Gatz, 1979;Watson & Balon, 1984 Lower values indicate species with depressed bodies, expected for fish that exploit habitats with rapid water velocity (Watson & Balon, 1984;Oliveira, 2005) 3.…”

“…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 .…”

“…The relationship between body shape and resource use may be related to the evolutionary history of the species (Winemiller, 1991). 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).…”

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

“…Considering the ecomorphological paradigm, intraspecific morphological variations can result in subtle niche differences among the individuals, favoring the adaptation of some fish species according to changes in environmental conditions. These ideas are supported by studies conducted by Mittelbach et al (1992), Robinson et al (1993), Langerhans et al (2003), and Sampaio et al (2013).…”

Diet and ecomorphological relationships of four cichlid species from the Cuiabá River basin

“…Thus, investigations on the relationship of the phenotype of a species to its use of the habitat can identify ecomorphological similarities between phylogenetically distant species (Chalcraft & Resetarits Jr., 2003;Oliveira et al, 2010), or establish ecomorphological differences among closely related species (Winemmiler et al, 1995;Wainwright et al, 2002). Many fish, including representatives of the same family (Kassan et al, 2003;Sampaio et al, 2013) or the same genus (Russo et al, 2004;Balassa et al, 2004;Corrêa et al, 2009), may have different feeding habits and associated divergence in their feeding structures. Studies have also shown that the morphology and feeding habits vary, even among individuals of the same species that occupy different environments (Meyer, 1990;Turigan et al, 1995).…”