The Trophic Niche of Two Sympatric Species of Salamanders (Plethodontidae and Salamandridae) from Italy

Amphibians are considered critical species in the nutrient flow within and across ecosystems, and knowledge on their trophic ecology and niches is crucial for their conservation. For the first time we studied for the first time the trophic ecology of the rare and endemic Salamandra atra aurorae in a mixed temperate forest in northern Italy. We aimed to define the realized trophic niche, investigate the prey selectivity and explore possible levels of individual specialization. In summer 2022 we obtained stomach contents from 53 salamanders by stomach flushing and prey availability using pitfall traps. We used the Costello graphical method to analyse the realized trophic niche, and the relativized electivity index to study prey selectivity. Our results show that the Golden Alpine salamander adopts a generalist feeding strategy with positive selection of few prey categories (e.g., Myriapoda, Hymenoptera except Formicidae). Food preference seems to be driven by size, movement ability and chitinization of the prey. A high degree of inter-individual diet variation, modularity and clustering was found, describing a scenario that can be framed in a Distinct Preference model framework. This study gives new insights on the trophic ecology of the Alpine salamander complex, whose subspecies appear to adopt similar feeding strategies.

Section: Discussionsupporting

confidence: 91%

Rare and Hungry: Feeding Ecology of the Golden Alpine Salamander, an Endangered Amphibian in the Alps

Centomo,

Roner,

Salvatori

et al. 2023

“…By shifting their surface activity, S. strinatii and S. perspicillata can co-occur at high densities while minimizing competitive interactions. On the other hand, trophic niche differentiation, divergences in metabolism, prey selection or behavioral traits, together with a high prey abundance may help to prevent the emergence of competition for food resources and may promote species coexistence [ 65 ]. Nevertheless, further studies in different ecological situations and adopting different sampling frameworks specifically designed to model surface activity should be conducted to help clarify the role of temporal or spatial niche partitioning in shaping the coexistence of these salamander species.…”

Section: Discussionmentioning

confidence: 99%

Disentangling Exploitative and Interference Competition on Forest Dwelling Salamanders

Rosa

Salvidio

Costa

2023

Exploitative competition and interference competition differ in the way access to resources is modulated by a competitor. Exploitative competition implies resource depletion and usually produces spatial segregation, while interference competition is independent from resource availability and can result in temporal niche partitioning. Our aim is to infer the presence of spatial or temporal niche partitioning on a two-species system of terrestrial salamanders in Northern Italy: Speleomantes strinatii and Salamandrina perspicillata. We conducted 3 repeated surveys on 26 plots in spring 2018, on a sampling site where both species are present. We modelled count data with N-mixture models accounting for directional interactions on both abundance and detection process. In this way we were able to disentangle the effect of competitive interaction on the spatial scale, i.e., local abundance, and from the temporal scale, i.e., surface activity. We found strong evidence supporting the presence of temporal niche partitioning, consistent with interference competition. At the same time, no evidence of spatial segregation has been observed.

“…The number of elongate (wormlike) prey consumed by Speleomantes was generally low (6.36%) but increased in surface populations, although remaining a small fraction of the overall diet (5.16% of the recognized prey in subterranean populations vs. 16.05% in the surface populations) (Table S1). Analyzing the stomach contents of the sympatric fire salamander (Salamandra salamandra) for a forest population of S. italicus [48], elongate prey represented 58.2% of the consumed prey for this species, allowing to confidently assume that there was not a shortage of such prey but probably Speleomantes consumed different ones. An experiment in which both prey typologies and abundances are experimentally controlled may help in establishing whether preference rather than opportunism is the major driver of prey selection in Speleomantes.…”

Section: Flying Vs Walking Preymentioning

confidence: 99%

“…Overall, only 120 Pulmonata have been recognized from the analyzed data sets (0.68%) (Table S1). Interestingly, only six were slugs, recognized from four individuals in an epigeous population of S. italicus [48]. The remaining prey of the category were small snails (with external shell).…”

Section: "Unfriendly" Preymentioning

confidence: 99%

Inferring on Speleomantes Foraging Behavior from Gut Contents Examination

Cianferoni,

Lunghi

2023

Self Cite

We here provide the first comprehensive analysis and discussion on prey consumed by the European cave salamanders of the genus Speleomantes. Our study stems from the need to shed light on the still unknown foraging behavior adopted by Speleomantes cave salamanders. Starting from the published datasets on gut contents from all Speleomantes species (including hybrids), we here discuss additional information (i.e., species ecology, lower taxonomic level), which were systematically omitted from those data sets. We analyzed a data set consisting of 17,630 records from 49 categories of consumed prey recognized from gut contents of 2060 adults and juveniles Speleomantes. Flying prey accounted for more than 58% of the prey items, while elongated crawling prey accounted for no more than 16% of the diet within a single population. Among the total recognized prey items, only three can be surely ascribed to the group of strictly-cave species (i.e., troglobites), meaning that European cave salamanders mostly forage in surface environment, and therefore represent one of the major drivers of allochthonous organic matter in subterranean environments. Some of the consumed prey seemed to be aquatic, allowing us to hypothesize whether Speleomantes are able to catch prey from a shallow body water. Furthermore, European cave salamanders possess the ability to prey upon taxa characterized by particular anti-predator defenses, while morphological constraints seem to be the most important limit to prey consumption. For each specific case, we provide insights and propose hypotheses concerning the foraging behavior that need to be tested to properly understand the foraging behavior of this cryptic salamanders.