Aim of the work. This paper presents a method to evaluate if competition is involved in determining the spatial niche of intestinal parasites. Materials and methods. This method has been applied to the study of large intestinal helminths of 50 slaughtered horses. The whole study has recently been published (Stancampiano et al, 2010 Vet Parasitol doi:10.1016/j.vetpar.2010.01.031). Results. Here we present the results regarding the relationship between two similar species, Strongylus vulgaris and Strongylus edentatus, found throughout the large intestine, but more abundant in the caecum and ventral colon respectively, according to the typical species composition of each intestinal region. The role of ecological interactions on the spatial niche occupation, in particular the interspecific competition, is considered to be absent because of the absence of negative pairwise correlations between helminth species. In our opinion, the absence of these correlations does not demonstrate that competition is not occurring. Therefore, after a preliminary Spearman’s test highligting positive pairwise correlations only, two negative binomial regressions were performed with S. vulgaris as dependent variable, in the caecum and ventral colon respectively, demostrating that the presence of S. vulgaris in a particular site is influenced by the presence of S. edentatus. Conclusions. This kind of negative relations has never been highlighted before because the positive relation between the overall abundances of the two species, due to similar epidemiological frameworks, usually hides the ecological phenomenon of spatial competition avoiding its disclosure. This aspect was controlled in the model by the peculiar inclusion of the total number of S. vulgaris itself as independent variable.

Competition for spatial niche: a disregarded ecological factor in structuring intestinal parasite communities

STANCAMPIANO, LAURA;MUGHINI GRAS, LAPO
2010

Abstract

Aim of the work. This paper presents a method to evaluate if competition is involved in determining the spatial niche of intestinal parasites. Materials and methods. This method has been applied to the study of large intestinal helminths of 50 slaughtered horses. The whole study has recently been published (Stancampiano et al, 2010 Vet Parasitol doi:10.1016/j.vetpar.2010.01.031). Results. Here we present the results regarding the relationship between two similar species, Strongylus vulgaris and Strongylus edentatus, found throughout the large intestine, but more abundant in the caecum and ventral colon respectively, according to the typical species composition of each intestinal region. The role of ecological interactions on the spatial niche occupation, in particular the interspecific competition, is considered to be absent because of the absence of negative pairwise correlations between helminth species. In our opinion, the absence of these correlations does not demonstrate that competition is not occurring. Therefore, after a preliminary Spearman’s test highligting positive pairwise correlations only, two negative binomial regressions were performed with S. vulgaris as dependent variable, in the caecum and ventral colon respectively, demostrating that the presence of S. vulgaris in a particular site is influenced by the presence of S. edentatus. Conclusions. This kind of negative relations has never been highlighted before because the positive relation between the overall abundances of the two species, due to similar epidemiological frameworks, usually hides the ecological phenomenon of spatial competition avoiding its disclosure. This aspect was controlled in the model by the peculiar inclusion of the total number of S. vulgaris itself as independent variable.
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Stancampiano L.; Mughini Gras L.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/90505
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