Is coexistence between non-native and native Erythrinidae species mediated by niche differentiation or environmental filtering? A case study in the upper Paraná River floodplain

Larissa S Pereira,Fábio T Mise,Angelo A Agostinho,Luiz F C Tencatt,Matheus T Baumgartner

doi:10.1590/1982-0224-20160142

Larissa S Pereira, Fábio T Mise + Show 3 more

Open Access

https://doi.org/10.1590/1982-0224-20160142

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Abstract

ABSTRACT The limiting similarity theory predicts that divergence in the functional traits of native and introduced species is an essential component in species establishment, as introduced species must occupy a niche that is unoccupied by resident species. On the other hand, the environmental filtering hypothesis predicts convergence between introduced and native species, as both possess traits that make them adapted to the local abiotic environment. Morphology, spatial co-occurrence, diet, feeding selectivity, and niche breadth and overlap of Erythrinidae were evaluated to detect possible mechanisms acting in the coexistence between non-native and native species. Native (Hoplias sp. B and Hoplias cf. malabaricus) and non-native (Hoplerythrinus unitaeniatus and Hoplias mbigua) species presented differences in morphological traits, spatial co-occurrence, diet, selectivity, and niche breadth and overlap. The mechanisms mediating species coexistence seem to vary according to species. The absence of spatial and feeding overlap suggests that non-native species H. unitaeniatus occupy a different niche than native species, supporting its successful establishment without eliminating the native species. However, low feeding overlap and similar morphologies between non-native and native species of Hoplias point to environmental filters; in this case, the non-native H. mbigua is able to establish due to similarities in functional traits.

Highlights

Theories about competition and niche segregation predict that species coexistence is achieved through differences in species niches
The ordination (PCA; Fig. 1) revealed three significant axes according to the brokenstick criteria (Table 2), but the analysis of variance (ANOVA) applied to the principal components analysis (PCA) scores did not present significant values for the second axis (F3,85=1.52, p=0.21), so it was not retained for interpretation
Non-native species should present adaptations that enable their establishment through niche segregation and/or environmental filtering, as they would have to survive under different abiotic conditions and interspecific interactions

Summary

Introduction

Theories about competition and niche segregation predict that species coexistence is achieved through differences in species niches. Species coexistence can be mediated by environmental filters, as predicted by the niche filtering hypothesis (sensu Southwood, 1977) In this case, coexisting species would be more similar to one another than expected by chance due to the abiotic properties of the habitat, which would act as a filter allowing only a narrow spectrum of species to survive (Zobel, 1997). According to this hypothesis, habitat characteristics can be viewed as filters imposed on species gene pools to select traits suited to a particular set of environmental conditions (Diaz et al, 1998), resulting in a higher degree of biological similarity among coexisting species than would be expected by chance (Cornwell et al, 2006; Mouillot et al, 2007). Considering introductions, once species have passed through dispersal and abiotic filters, that is, they were able to arrive at a site, survive and grow under the prevailing conditions, niche-based interactions will have little or no effect on these species interactions (Thompson et al, 2010)

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