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. 2023 Apr 7;13(8):1281.
doi: 10.3390/ani13081281.

Size-Mediated Trophic Interactions in Two Syntopic Forest Salamanders

Andrea Costa  1 , Giacomo Rosa  1 , Sebastiano Salvidio  1
Affiliations

Size-Mediated Trophic Interactions in Two Syntopic Forest Salamanders

Andrea Costa et al. Animals (Basel). .

Abstract

Exploitative competition and interference competition differ in the way they affect re-source availability for competitors: in the former, organisms reduce resource availability for the competitors; in the latter, one organism actively prevents the competitor from accessing resources, independently of their availability. Our aim is to test for the presence of foraging competition in two forest-dwelling salamanders in Italy: Speleomantes strinatii and Salamandrina perspicillata. We also aim at testing for size-mediated competition. We obtained stomach contents from 191 sampled individuals by means of stomach flushing at 8 sampling sites where both species occur. We focused our analysis on the core prey taxa shared by both species: Collembola and Acarina. We found that the foraging activity of S. perspicillata is positively affected by body size and negatively affected by potential competitor's activity on the forest floor during the sampling, which also significantly weakened the positive relationship with body size. These results suggest the presence of an interference/interaction occurring between the two species and affecting the foraging activity of S. perspicillata. This competitive interaction is size mediated and configured as interference competition rather than exploitative competition.

Keywords: competition; diet; foraging; interference competition; salamander; species interaction.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Map depicting the location of the eight sampling sites in Northern Italy. Site IDs on the right box correspond to Table 1, where additional details on site municipality and sample sizes are provided. Precise locations of sampling sites are not provided, to avoid poaching and pathogen spread.
Figure 2
Figure 2
Plot representing the effect of body size (SVL) on the consumption of Collembola and Acarina for both S. perspicillata and S. strinatii when the potential competitor is present (purple) or absent (green) on the forest floor, as estimated by Poisson GLMs.
See this image and copyright information in PMC

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