Project

Salamanders as prey and predators

Goal: The objective of this project is to better understand the ecological role of salamanders both as predators and as prey. In particular, the habitat selection, population abundance and the feeding ecology of terrestrial salamanders will be analysed in different species and in different conspecific populations. Moreover, by using realistic clay models the predation pressure acting upon salamanders living in different habitats will also be assessed.

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Project log

Sebastiano Salvidio
added an update
A recent paper has been published on Ethology Ecology and Evolution about the trophic strategy of Speleomantes strinatii and Salamandrina perspicillata. Enjoy reading.
Foraging success is differently affected by local climate in two syntopic
forest-dwelling salamanders. by Giacomo Rosa, Mattia Bosio, Sebastiano Salvidio , and Andrea Costa.
Abstract
Amphibians are small ectothermic vertebrates with high permeable skins that are highly constrained by environmental conditions, such as humidity and temperature. Therefore, terrestrial salamanders regulate their surface activity, including foraging, to minimize evaporative water loss. The influence of local micro-climatic factors on the foraging success of European forest dwelling salamanders has rarely been analysed in detail.
We examined the role of local climatic conditions on the foraging success, measured by the total number of prey items, of two syntopic forest-dwelling salamanders: Strinati’s cave salamander, Speleomantes strinatii (family Plethodontidae), and Northern spectacled salamander, Salamandrina perspicillata (family Salamandridae). We evaluated the effects of rainfall, temperature and body size on the foraging success of these two species, in eight sampling sites in the Northern Apennines of Italy, for a total of 11 salamander populations. Our findings show that different climatic variables affected the two species differently. Salamandrina perspicillata foraged more intensively during periods of prolonged rainfall with higher temperatures. On the contrary, S. strinatii foraging success was negatively influenced by rising temperature, while rainfall seemed to have no significant effect. Interestingly, body size increased success in S. perspicillata but not in S. strinatii. Overall, our findings show that, when foraging in the same environment, these two species are conditioned by different climatic factors possibly due to their differences in overall body size and their ability to resist dehydration.
 
Sebastiano Salvidio
added a research item
Amphibians are small ectothermic vertebrates with high permeable skins that are highly constrained by environmental conditions, such as humidity and temperature. Therefore, terrestrial salamanders regulate their surface activity, including foraging, to minimize evaporative water loss. The influence of local micro-climatic factors on the foraging success of European forest dwelling salamanders has rarely been analysed in detail. We examined the role of local climatic conditions on the foraging success, measured by the total number of prey items, of two syntopic forest-dwelling salamanders: Strinati's cave salamander, Speleomantes strinatii (family Plethodontidae), and Northern spectacled salamander, Salamandrina perspicillata (family Salamandridae). We evaluated the effects of rainfall, temperature and body size on the foraging success of these two species, in eight sampling sites in the Northern Apennines of Italy, for a total of 11 salamander populations. Our findings show that different climatic variables affected the two species differently. Salamandrina perspicillata foraged more intensively during periods of prolonged rainfall with higher temperatures. On the contrary, S. strinatii foraging success was negatively influenced by rising temperature, while rainfall seemed to have no significant effect. Interestingly, body size increased success in S. perspicillata but not in S. strinatii. Overall, our findings show that, when foraging in the same environment, these two species are conditioned by different climatic factors possibly due to their differences in overall body size and their ability to resist dehydration.
Sebastiano Salvidio
added an update
Dear Colleagues,
the book "The Ecological Role of Salamanders as Predators and Prey" has now been publised. This volume is a printed edition of the Special Issue The Ecological Role of Salamanders as Predators and Prey that was published in Diversity.
Good reading,
Sebastiano
 
Sebastiano Salvidio
added an update
Dear Friends and Collegues,
the Editorial for the special issue of "Diversity" has now been published. It is available from the Journal website:
or from my Researchgate website.
Enjoy the reading,
Sebastiano
 
Sebastiano Salvidio
added a research item
Salamanders comprise more than 700 living species, mainly found in the Northern hemisphere (i.e., North and Central America and the northern part of Eurasia), and the Amazon region of South America. Salamanders constitute a diverse clade of amphibians with different reproduction modes that range from completely aquatic to fully terrestrial [1]. Salamanders are key components of many temperate forest ecosystems, in particular in North America [2] and in high altitude lakes, where fish are naturally absent [3]. In these temperate ecosystems, salamanders and newts are top predators that regulate top down the invertebrate prey community [4], while at the same time being high-energetic prey items for birds, mammals and reptiles [5]. In any case, despite their ecological importance, the role of salamanders in resource-consumer networks remains remarkably understudied. Therefore, this Special Issue aims to better understand the different ecological roles of these small vertebrates, both in aquatic and terrestrial ecosystems. Indeed, the eight papers published addressed many of the issues related to the trophic strategies and the trophic position of salamanders in the ecological food web. In particular, one review paper [6] makes a significant contribution to our understanding of salamander and newt populations functioning as predators, competitors and prey in freshwater ecosystems. Furthermore, it appears relevant that four papers were all conducted in underground habitats, both of natural or artificial origin [7-10]. This relatively high number of papers dedicated to the ecological structure and functioning of underground ecosystems clearly indicates a recent growing interest of ecol-ogists and conservation biologists over this highly understudied environment [11,12]. Indeed , in underground habitats, salamanders are, together with cave fish, the only vertebrates that were able to permanently establish reproductive populations. This fact highlights the adaptability of salamanders to extreme subterranean habitats, that were probably colonized to reduce the environmental stress and the predation level experienced in adjacent epigean habitats [13]. Two other papers of this Special Issue analyze the diet of terrestrial salamanders, the first in Spain [14] and the second in Italy [15]. In the former paper, a novel COI metabarcoding approach was used to analyze the dietary habits of the fire salamander Salamandra salamandra [14], while in the latter, the authors applied for the first time in salamanders the technique of network analysis to study the trophic strategy of the Alpine salamander Salamandra atra [15]. Finally, one paper tested the niche variation hypothesis [16] in a newt community sampled in a complex system of artificial aquatic sites [17]. These authors found that individual specialization was widespread in all populations and also provided novel insights on the level of dissimilarity of individual trophic variation in closely related and ecologically similar newt species [17]. Despite the diverse topics that were discussed by all these papers, other interesting issues involving the role of salamanders in the trophic web and their complex behaviors remain to be elucidated and deserve further attention. For example, aposematic displays and deimatic behaviors of salamanders (i.e., startling visual or auditive signals that distract a predator, giving the attacked prey an opportunity to escape) have received little attention by behavioral ecologists [18]. However, separating aposematism from dei-matism in brightly colored salamanders or newts may be challenging [19]. This because the same visual signal may be perceived in a completely different way by animals
Sebastiano Salvidio
added an update
A new paper has been published in the Special Issue "The Ecological Role of Salamanders as Predators and Prey" in the Journal Diversity:
COI Metabarcoding Provides Insights into the Highly Diverse Diet of a Generalist Salamander, Salamandra salamandra (Caudata: Salamandridae), by Marques, Mata and Velo-Antón.
The paper is open access:
Enjoy the reading.
Sebastiano
 
Sebastiano Salvidio
added an update
Happy new year!
A recent study on salamander aposematism has been pulished on Acta Herpetologica, the Journal of the Italian Herpetological Society. You may dowload the pdf from my Researchgate site. Here below the title, authors and abstract:
Is the Northern Spectacled Salamander Salamandrina perspicillata aposematic? A preliminary test with clay models. Giacomo Barbieri, Andrea Costa, Sebastiano Salvidio.
Abstract. Aposematism is a visual communication system in which bright and contrasted coloured prey warn predators about their unprofitability. The Northern Spectacled Salamander Salamandrina perspicillata, a small terrestrial salamander endemic to Italy, displays a uniform dark dorsal colouration and a contrasted ventral side in which a bright red colour is displayed by coiling the tail over the body. In amphibians, this behaviour, known as “Unkenreflex”, is usually considered to be aposematic. In this study, we used realistic plasticine replicas to test this aposematic hypothesis
in the Northern Spectacled Salamander. Of the 199 clay models placed in a natural habitat, 165 (83%) were recovered and 39 (24%) showed some sign of predation. The head of the models was more attacked than expected by chance (P = 0.042), suggesting that potential predators were perceiving models as real prey. However, there were no differences in the proportion of dorsal (18/83 = 22%), and ventral (21/82 = 26%) models attacked by predators. Therefore, contrary
to expectations our experiment did not support the aposematic hypothesis. However, predation experiments with clay models have limitations and our results should be considered as preliminary, deserving further research to better understand the Northern Spectacled salamander prey-predator system.
 
Sebastiano Salvidio
added a research item
Aposematism is a visual communication system in which bright and contrasted coloured prey warn predators about their unprofitability. The Northern Spectacled Salamander Salamandrina perspicillata, a small terrestrial sal-amander endemic to Italy, displays a uniform dark dorsal colouration and a contrasted ventral side in which a bright red colour is displayed by coiling the tail over the body. In amphibians, this behaviour, known as "Unkenreflex", is usually considered to be aposematic. In this study, we used realistic plasticine replicas to test this aposematic hypothesis in the Northern Spectacled Salamander. Of the 199 clay models placed in a natural habitat, 165 (83%) were recovered and 39 (24%) showed some sign of predation. The head of the models was more attacked than expected by chance (P = 0.042), suggesting that potential predators were perceiving models as real prey. However, there were no differences in the proportion of dorsal (18/83 = 22%), and ventral (21/82 = 26%) models attacked by predators. Therefore, contrary to expectations our experiment did not support the aposematic hypothesis. However, predation experiments with clay models have limitations and our results should be considered as preliminary, deserving further research to better understand the Northern Spectacled salamander prey-predator system.
Sebastiano Salvidio
added an update
The short note "Is the Northern Spectacled Salamander Salamandrina perspicillata
aposematic? A preliminary test with clay models" by arbieri, Costa and Salvidio will be published on the Jornal ACTA HERPETOLOGICA before the end of the year. We used clay models to test if the species ventral colouration was deterring predation. Here is the abstract:
Aposematism is a visual communication system in which bright and contrasted coloured prey warn predators about their unpro/tability. 0e Northern Spectacled Salamander Salamandrina perspicillata, a small terrestrial salamander endemic to Italy, displays a uniform dark dorsal colouration and a contrasted ventral side in which a bright red colour is displayed by coiling the tail over the body. In amphibians, this behaviour, known as “Unkenre!ex”, is usually considered to be aposematic. In this study, we used realistic plasticine replicas to test this aposematic hypothesis in the Northern Spectacled Salamander. Of the 199 clay models placed in a natural habitat, 165 (83%) were recovered and 39 (24%) showed some sign of predation. 0e head of the models was more attacked than expected by chance (P = 0.042), suggesting that potential predators were perceiving models as real prey. However, there were no di1erences in the proportion of dorsal (18/83 = 22%), and ventral (21/82 = 26%) models attacked by predators. Therefore, contrary to expectations our experiment did not support the aposematic hypothesis. However, predation experiments with clay models have limitations and our results should be considered as preliminary, deserving further research to better
understand the Northern Spectacled salamander prey-predator system.
 
Sebastiano Salvidio
added an update
I am pleased to inform all readers that the special issue "The Ecological Role of Salamanders as Predators and Prey" will be accepting submissions until December 31, 2021. See the link:
https://www.mdpi.com/journal/diversity/special_issues/salamanders_prey Recentky, Diversity has received an increased Impact Factor of 2.465 in the latest edition of the Journal Citation Reports®, published by Clarivate Analytics in June 2021. Diversity now ranks 27/60 Q2 in JCR “Biodiversity Conservation” category and 92/166 Q3 in “Ecology” category.
If you are willing to submit and you have questions about the suitabilityt of your manuscript do not hesitate to contact me:
Sebastiano Salvidio <sebastiano.salvidio@unige.it>
 
Sebastiano Salvidio
added an update
The article "Ecological Observations on Hybrid Populations of European Plethodontid Salamanders, Genus Speleomantes" has been published in Diversity as part of the Special Issue The Ecological Role of Salamanders as Predators and Prey and is available online: Abstract: https://www.mdpi.com/1424-2818/13/7/285 PDF Version: https://www.mdpi.com/1424-2818/13/7/285/pdf Special Issue: https://www.mdpi.com/journal/diversity/special_issues/salamanders_prey
 
Andrea Costa
added a research item
In vertebrates, the main tissue devoted to energy storage is the adipose tissue. In salamanders, energy reserves can also be stored in the adipose tissues of the tail. Therefore, we evaluated if energy storage in salamanders' tails is related to individual body condition, life cycle and environmental constraints. We calculated a scaled measure of tail width for 345 salamanders belonging to six Mediterranean taxa exhibiting wide phylogenetic, behavioural and ecological variation. We related this measure to the Scaled Mass Index (SMI), a body condition index which reliably predicts body fat. We found significant relationships between the SMI and scaled tail width in the terrestrial Spectacled salamander and Alpine salamanders, independently of sex. At the same time, we found that energy storage in the tail is maximum in Alpine Salamanders, which experience reduced activity periods and restricted access to resources. Conversely, we found a significant effect of sex in Imperial cave salamanders, where females store reserves in the tail to counterbalance resource investment in parental care, and in Corsican Brook Newts, where the reproductive function of males' tails may imply a greater tail width. Finally, in the biphasic Great Crested Newt, tail width was not related to SMI in both sexes.
Sebastiano Salvidio
added an update
MDPI has recently reopened the journal Diversity special issue "The Ecological Role of Salamanders as Predators and Prey” with a new deadline 31 December 2021:
In this issue six papers on this interesting topic have already being published.
Sebastiano Salvidio
 
Andrea Costa
added a research item
Animal personality is a relatively neglected field in amphibian research. In this study we assessed the influence of stomach flushing, a non-lethal technique used in amphibian dietary studies, on the boldness behaviour of the cave salamander Speleomantes strinatii. The time of emergence from a shelter located in an unfamiliar environment (a proxy for individual boldness) was measured in 26 cave salamanders before and after stomach flushing, while 14 non-flushed salamanders were tested as controls. Boldness was a repeatable behaviour for salamanders and larger individuals emerged from their shelter more rapidly than smaller ones. Linear mixed model analysis showed that flushing, sex and body condition had no effect on this behaviour. These findings are promising in the framework of the study of salamander personality. In particular, our results will be useful when exploring the relationship between individual trophic strategy and boldness, aggression or exploration behaviours in terrestrial salamanders.
Sebastiano Salvidio
added an update
The preprint of our paper on network analysis of salamanders trophic systems is now avalible.
Enjoy the reading,
Sebastiano
 
Sebastiano Salvidio
added an update
The paper "Weighted individual‐resource networks in prey‐predator systems: the role of prey availability on the emergence of modular structures" by Costa, Romano, Rosa and Salvidio, has been recently accepted on Integrative Zoology. DOI: 10.1111/1749-4877.12520 . I will soon provide the Abstract and more details.
Best
Sebastiano Salvidio
 
Andrea Costa
added a research item
Ecological networks, usually depicting interactions among species, have been recently down‐scaled to the individual level, permitting description of patterns of inter‐individual resource variation, that are usually hindered at the species level. Optimal diet theory (ODT) models, applied to prey‐predator systems, predict different patterns of nestedness and modularity in the network, depending on the available resources and intra‐specific competition. The effect of resource availability on the emergence of networks structures, and ODT framework, has not yet fully been clarified. Here we analyzed the structural patterns of individual‐resource networks in three species of Mediterranean salamanders, in relation to changes in prey availability. We used weighted individual‐resource network metrics to interpret the observed patterns, according to three ODT models. We found significant nestedness recurring in our study system, indicating that both selective and opportunistic individuals occur in the same population. Prey diversity, rather than abundance, was apparently related to inter‐individual resource variation and promoted the emergence of significant modularity within all networks. The observed patterns of nestedness and modularity, together with the variation in resource diversity and intra‐specific competition, is in agreement with the distinct preferences model of ODT. These findings suggest that in the focal prey‐predator systems, individuals were able to perceive changes in prey diversity and to exploit in different ways the variations in composition of available resources, shifting their diet assembly rules accordingly. Our findings also confirm that the use of weighted individual‐resource networks, in prey‐predator systems, allows to disclose dynamics that are masked at the species or population level. https://onlinelibrary.wiley.com/share/author/IQBWGVIRVX5PIPUIRYTF?target=10.1111/1749-4877.12520
Sebastiano Salvidio
added an update
Good day,
this update concerns the recent paper "Reliability of multinomial N-mixture models for estimating
abundance of small terrestrial vertebrates" by Costa, Romano and Salvidio. this study has been recently published in Biodiversity and Conservation (2020) 29:2951–2965. Although, it not relates directly with trophic habits or predation of salmanders, this paper is relevant because provides a cost-effective method to estimate salamander abundance in different habitats. Obviously, salamander population density is relevant when analyzing predation rate or trophic strategies of our focal salamander populations.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added an update
Good day,
this update concerns the recent paper "Reliability of multinomial N-mixture models for estimating
abundance of small terrestrial vertebrates" by Costa, Romano and Salvidio. this study has been recently published in Biodiversity and Conservation (2020) 29:2951–2965. Although, it not relates directly with trophic habits or predation of salmanders, this paper is relevant because provides a cost-effective method to estimate salamander abundance in different habitats. Obviously, salamander population density is relevant when analyzing predation rate or trophic strategies of our focal salamander populations.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added an update
Good day,
this update concerns the recent paper "Reliability of multinomial N-mixture models for estimating
abundance of small terrestrial vertebrates" by Costa, Romano and Salvidio. this study has been recently published in Biodiversity and Conservation (2020) 29:2951–2965. Although, it not relates directly with trophic habits or predation of salmanders, this paper is relevant because provides a cost-effective method to estimate salamander abundance in different habitats. Obviously, salamander population density is relevant when analyzing predation rate or trophic strategies of our focal salamander populations.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added an update
Good day,
this update concerns the recent paper "Reliability of multinomial N-mixture models for estimating
abundance of small terrestrial vertebrates" by Costa, Romano and Salvidio. this study has been recently published in Biodiversity and Conservation (2020) 29:2951–2965. Although, it not relates directly with trophic habits or predation of salmanders, this paper is relevant because provides a cost-effective method to estimate salamander abundance in different habitats. Obviously, salamander population density is relevant when analyzing predation rate or trophic strategies of our focal salamander populations.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added an update
Good day,
this update concerns the recent paper "Reliability of multinomial N-mixture models for estimating
abundance of small terrestrial vertebrates" by Costa, Romano and Salvidio. this study has been recently published in Biodiversity and Conservation (2020) 29:2951–2965. Although, it not relates directly with trophic habits or predation of salmanders, this paper is relevant because provides a cost-effective method to estimate salamander abundance in different habitats. Obviously, salamander population density is relevant when analyzing predation rate or trophic strategies of our focal salamander populations.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added an update
Dear Colleagues,
the Special Issue of the journal Diversity (ISSN 1424-2818), composed by six papers,
is available open access.
Have a nice read.
Sebastiano
"The Ecological Role of Salamanders as Predators and Prey"
Guest Editor(s): Salvidio Sebastiano.
Salvidio, S.; Costa, A.; Oneto, F.; Pastorino, M.V. Variability of A
Subterranean Prey-Predator Community in Space and Time. Diversity 2020,
12(1), 17;
Sánchez-Hernández, J. Reciprocal Role of Salamanders in Aquatic Energy Flow
Pathways. Diversity 2020, 12(1), 32;
Manenti, R.; Lunghi, E.; Barzaghi, B.; Melotto, A.; Falaschi, M.; Ficetola,
G.F. Do Salamanders Limit the Abundance of Groundwater Invertebrates in
Subterranean Habitats? Diversity 2020, 12(4), 161;
Lunghi, E.; Cianferoni, F.; Ceccolini, F.; Zhao, Y.; Manenti, R.; Corti, C.;
Ficetola, G.F.; Mancinelli, G. Same Diet, Different Strategies: Variability
of Individual Feeding Habits across Three Populations of Ambrosi’s Cave
Salamander (<i>Hydromantes ambrosii</i>). Diversity 2020, 12(5), 180;
Mirabasso, J.; Bissattini, A.M.; Bologna, M.A.; Luiselli, L.; Stellati, L.;
Vignoli, L. Feeding Strategies of Co-occurring Newt Species across Different
Conditions of Syntopy: A Test of the “Within-Population Niche Variation”
Hypothesis. Diversity 2020, 12(5), 181;
Roner, L.; Costa, A.; Pedrini, P.; Matteucci, G.; Leonardi, S.; Romano, A. A
Midsummer Night’s Diet: Snapshot on Trophic Strategy of the Alpine
Salamander, <i>Salamandra atra</i>. Diversity 2020, 12(5), 202;
 
Sebastiano Salvidio
added an update
The Special Issue of the Journal "Diversity" devoted to Salamanders has been published online. Read the last papers at:
Best
Sebastiano
 
Antonio Romano
added a research item
Information on the trophic ecology of the Alpine salamander, Salamandra atra, is scattered and anecdotal. We studied for the first time the trophic niche and prey availability of a population from an area located in Italian Dolomites during the first half of August. Considering that S. atra is a typical nocturnal species, we collected food availability separately for diurnal and nocturnal hours. Our aims were: (i) to obtain information on the realized trophic niche; (ii) to provide a direct comparison between trophic strategy considering only nocturnal preys or considering all preys; (iii) to study trophic strategy of this species at the individual level. In two samplings nights we obtained prey from 50 individuals using stomach flushing technique. Trophic strategy was determined using the graphical Costello method and selectivity using the relativized electivity index. During the short timeframe of our sample, this salamander showed a generalized trophic strategy. The total trophic availability differed significantly from nocturnal availability. Interindividual diet variation is discussed in the light of the optimal diet theory. Finally, we highlighted that considering or not the activity time of the studied taxon and its preys may lead to a conflicting interpretation of the trophic strategies.
Sebastiano Salvidio
added an update
New papers have been added to the Special issue of Diversity and more will be published soon.
Enjoy the reading,
Best
Sebastiano Salvidio
 
Sebastiano Salvidio
added an update
An interesting paper has been published in the Journal Diversity: "Reciprocal Role of Salamanders in Aquatic Energy Flow Pathways" by Javier Sánchez-Hernández; doi:10.3390/d12010032.
Good read,
Sebastiano Salvidio
 
Sebastiano Salvidio
added an update
Recently a new paper on the trophic ecology of a Spleomantes strinatii population living underground has benn published: "Variability of A Subterranean Prey-Predator
Community in Space and Time" by Salvidio, Costa, Oneto, Pastorino. This article belongs to the Special Issue of the journal Diversity "The Ecological Role of Salamanders as Predators and Prey". Have a good read and a happy 2020.
Sebastiano Salvidio
 
Sebastiano Salvidio
added an update
Hi to everybody,
a recent paper on the trophic strategy of the endemic Corsican newt Euproctus montanus has been published.
"Trophic strategies of two newt populations living in contrasting habitats on a Mediterranean island" by Rosa, Costa and Salvidio. Ethology, Ecology and Evolution.
The paper is freele available both on Researchgate and on the Journal website.
Have a nice read.
Sebastiano
 
Andrea Costa
added a research item
In amphibians, the study of trophic niche is important to better understand the species ecological adaptation, in particular along gradients or in heterogeneous habitats. In this framework, we analysed the trophic strategies of two populations of the endemic Corsican brook newt Euproctus montanus, one living in a Mediterranean lowland and the other in a mountain stream. In both sites, we performed dietary analysis using stomach flushing and assessed the available invertebrate prey community. Further, we estimated newt density using removal sampling. Streams were similar in invertebrate prey abundance (P = 0.15), but differed in prey diversity (P < 0.001), the Mediterranean lowland site possessing a higher diversity of invertebrate prey. The newts' trophic strategies were analysed at the population level and also at the individual one to assess in detail the trophic specialization. In both sites newt density was similar and the population realized trophic niche displayed a large overlap with the available prey community. Therefore, both populations behaved as broad trophic generalists. However, in the Mediterranean lowland stream, where available resources were more diverse, there was evidence of a significant degree of individual trophic specialization. This finding is consistent with the classic niche variation hypothesis, that predicts a higher individual differentiation in presence of high resource diversity.
Sebastiano Salvidio
added an update
Dear Colleagues,
I recently accepted to serve as the Guest Editor for a Special Issue of the journal Diversity (ISSN 1424-2818, Impact Factor 2.047) on the subject of "The Ecological Role of Salamanders as Predators and Prey". Contributions to this Special Issue are now accepted. The submitted article may be a full paper or short communication based on your own research in this area or a focused review article on some aspects of the subject.
Diversity (ISSN 1424-2818, Impact Factor 2.047) is a fully open access journal, granting the readers unlimited and free access, which increases publicity and promotes more frequent citations, as indicated by several studies. Open access is supported by the authors and their institutes, and an Article Processing Charge (APC) of CHF 1200 currently applies to all accepted papers (Please note that for papers submitted after 31 December 2019 an APC of 1400 CHF applies).
If you would like to submit an article, please let me know, in case I can offer advice or comment. In particular, if you were considering a review article, please inform us about the proposed topic area so that we can avoid having the same material covered by more than one author.
For more information about the Special Issue, please see: https://www.mdpi.com/journal/diversity/special_issues/salamanders_prey
For information on manuscript preparation and related matters, please see the instructions for authors: http://www.mdpi.com/journal/diversity/instructions
The deadline for submission of manuscripts to the Special Issue is 31 March 2020.
With best wishes,
Sebastiano Salvidio
 
Sebastiano Salvidio
added an update
At last, "Individual Trophic Specialisation in the Alpine Newt Increases with Increasing Resource Diversity" by Sebastiano Salvidio, Andrea Costa, Federico Crovetto 56(1-6), (27 May 2019)
The Authors thank the Editor of Annales Zoologici Fennici for processing this paper.
Have a nice read
Sebastiano
 
Sebastiano Salvidio
added a research item
Clay models are realistic replicas of live animals that are frequently used in ecological and ethological field studies. These kind of models, usually made from plasticine, are malleable, easy to shape, colour and relative inexpensive. In addition, plasticine models retain marks on their surface allowing the identification of the predator and of the body part of the prey that was attacked. In this short review we retrieved and analysed a preliminary list of studies published until December 2017, that used clay replicas of amphibians in ecological field studies. Overall 25 publications were analysed. The first scientific paper using amphibian clay models was published in 1994, but only after the year 2005 the use of clay replicas became frequent in herpetological field researches. The majority of studies were performed in tropical or subtropical ecosystems of Central and South America, and only a relative small number of studies were executed in temperate forests of North America and Europe. The most studied family was Dendrobatidae with nine species. In Urodela the Plethodontidae, with four species, was the most studied family. After the analysis of the main features concerning technical aspects, geographic distribution and temporal trend of these kind of studies, the pros and cons of the use of amphibian clay models are synthetically discussed.
Sebastiano Salvidio
added an update
I have just uploaded a short review on the use of clay plasticine or paraffin) models in amphibian ecological studies. Have a nice reading.
Best
Sebastiano
 
Sebastiano Salvidio
added a research item
Dietary studies suggest that amphibians are opportunistic predators. However, there is little information on the ability of individuals to change their feeding strategy in time because most studies do not evaluate prey availability and its effect on individual behaviour. To better understand how variation in prey availability may affect the feeding strategy of newts, we studied the Alpine newt, Ichthyosaura alpestris, during April and June in 2015, when we monitored prey availability and the species dietary habits. In April at low prey diversity, the newts were generalists, i.e., their diet overlapped almost completely with prey availability. In June when prey diversity was high, the newts became specialists. At the individual level, 9 out of 15 recaptured newts shifted from a generalist to a specialist feeding strategy from April to June, suggesting a rapid behavioural change in response to increasing prey diversity, in accordance with optimal foraging theory. These results stress the importance of sampling the same individuals several times during an extended period of time to better understand the patterns of diet variation in amphibians.
Sebastiano Salvidio
added an update
The abstract of the paper "Individual trophic specialisation in the Alpine newt increases with increasing resource diversity" by Salvidio, Costa and Corvetto is now available at: http://www.annzool.net/
This is the first longitudinal study (i.e. in which the same individuals are analysed over time) about the trophic specialization of amphibians.
The abstract is pasted below.
Have a nice read.
Sebastiano Salvidio
"Individual trophic specialisation in the Alpine newt increases with increasing resource diversity" by Salvidio, Costa and Corvetto. Ann. Zool. Fennici 56: 17–24 .
Abstract
Dietary studies suggest that amphibians are opportunistic predators. However, there is little information on the ability of individuals to change their feeding strategy in time because most studies do not evaluate prey availability and its effect on individual behaviour. To better understand how variation in prey availability may affect the feeding strategy of newts, we studied the Alpine newt, Ichthyosaura alpestris, during April and June in 2015, when we monitored prey availability and the species dietary habits. In April at low prey diversity, the newts were generalists, i.e., their diet overlapped almost completely with prey availability. In June when prey diversity was high, the newts became specialists. At the individual level, 9 out of 15 recaptured newts shifted from a generalist to a specialist feeding strategy from April to June, suggesting a rapid behavioural change in response to increasing prey diversity, in accordance with optimal foraging theory. These results stress the importance of sampling the same individuals several times during an extended period of time to better understand the patterns of diet variation in amphibians.
 
Sebastiano Salvidio
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I added to the project a recent conference paper that was presented at the XII Italian Herpetological Society (Societas herpetologica Italica) meeting, held at the University of Calabria from 1 to 5 October 2018.
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Sebastiano Salvidio
 
Sebastiano Salvidio
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I added the power-point presented as oral talk in Luxembourg, September 2011 during the Societas Europeae Herpetologica (SEH) meeting. This research was published the following year in Wildlife Research as:
CROVETTO F., ROMANO A., SALVIDIO S. (2012). A comparison of two non-lethal methods for dietary studies in terrestrial salamanders. Wildlife Research, 39: 266-270.
Have a nice reading,
Sebastiano
 
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Oral presentation at the European Congress of Herpetology, Luxembourg 25th-29th September 2011.
Sebastiano Salvidio
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I have just uploaded to this project the file " The use of clay models to assess potential predation on cave salamanders". This was presented as a speach to the 19th Societas Europea Herpetologica meeting - European Congress of Herpetology, held at the University of Salzburg, Austria, in September 2017.
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This is the presentation concerning the study of terrestrial salamander predation by means of clay replicas. The results from different experiments are discussed, and the pros and cons of the use of this material illustrated.
Sebastiano Salvidio
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Comportamenti territoriali e aggressività verso conspecifici e individui di altre specie sono stati ampiamente descritti nei Pletodontidi nordamericani fin dagli anni ’70. Tali comportamenti sono essenzialmente legati alla spar- tizione degli habitat e delle risorse trofiche, ma sono state evidenziate anche cause riconducibili alla protezione del nido. Per quanto riguarda i pletodon- tidi europei, aspetti riguardanti la territorialità di Speleomantes strinatii sono stati presi in considerazione da salvidio et al. (2002), zanetti & salvidio (2006), senza tuttavia rilevare specifici comportamenti in questa specie. nel 2010 e 2014 oneto et al. hanno verificato l’esistenza di comportamenti difensivi e ipotetici atteggiamenti aggressivi da parte di femmine durante la cova e la sorveglianza dei neonati all’interno della stazione Biospelologica di Besolagno (genova, Italia nord occidentale). Tali comportamenti sono stati ricondotti a forme di cure parentali portate dalle femmine di S. stri- natii nei confronti della prole per proteggerli da intrusi. In questo studio, approntato come prosecuzione delle ricerche precedenti, è stato allestito all’interno della stazione Biospeleologica un terrario sorvegliato da una vi- deocamera FullHD Praktica iX - 8, massima risoluzione 1920x1080, dotata di Infrared night Vision con incorporato illuminatore Ir ad alta potenza. Il fine è stato quello di registrare con maggiore precisione i comportamenti di una femmina di S. strinatii in presenza si individui conspecifici, in questo caso maschi, nel sito di deposizione. l’ottimo funzionamento della vide- ocamera, ha permesso di registrare per 7 giorni le interazioni fra intrusi e femmina con i neonati, evidenziando chiaramente comportamenti difensivi da parte di quest’ultima, culminati con aggressioni verso gli intrusi, morsi intensi e sostenuti, tuttavia anche in assenza di un reale pericolo verso i neonati. I futuri sviluppi della ricerca, saranno volti a definire se l’aumento dell’aggressività in questa specie sia determinata da meccanismi legati alla tutela dell’investimento energetico prodotto dalla femmina per portare alla schiusa le uova e alla sopravvivenza dei neonati.
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Hello to everybody,
I just added to this project the fulltext of my presentation to the XI Congress of the Italian Herpetological Society (SHI) hel in Trento in September 2016. This short note gives information about studies on individual trophic specialization in Italian amphibians and in particular in Italian salamanders.
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Sebastiano
 
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Recent studies have shown that many amphibian populations that behave as generalist feeders are in fact composed by a number of heterogeneous individuals, both specialized and generalists. Here we review the literature about individual trophic specialization in Italian amphibians and also present some original data. To date, the trophic specialization at the individual level has been studied only in five species of salamanders: one population each for Speleomantes strinatii, Salamandra salamandra and Icthyosaura alpestris and two populations for Salamandrina perspicillata and Speleomantes imperialis. Four adult populations and one larval population were studied, all by means of stomach flushing. In four species, populations displaying a relatively broad trophic niche (i.e. trophic generalists) were composed by both generalist and specialist individuals. In one species, the spectacled salamander Salamandrina perspicillata, the populations were specialized but consisted of a mixture of individuals with different trophic strategies. Individual diet variation, an issue that may give also relevant information on species’ conservation, has still to be assessed in many Italian amphibians, especially in frogs and toads.
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It has been suggested that Plethodontid salamanders are excellent candidates for indicating ecosystem health. However, detailed, long-term data sets of their populations are rare, limiting our understanding of the demographic processes underlying their population fluctuations. Here we present a demographic analysis based on a 1996-2008 data set on an underground population of Speleomantes strinatii (Aellen) in NW Italy. We utilised a Bayesian state-space approach allowing us to parameterise a stage-structured Lefkovitch model. We used all the available population data from annual temporary removal experiments to provide us with the baseline data on the numbers of juveniles, subadults and adult males and females present at any given time. Sampling the posterior chains of the converged state-space model gives us the likelihood distributions of the state-specific demographic rates and the associated uncertainty of these estimates. Analysing the resulting parameterised Lefkovitch matrices shows that the population growth is very close to 1, and that at population equilibrium we expect half of the individuals present to be adults of reproductive age which is what we also observe in the data. Elasticity analysis shows that adult survival is the key determinant for population growth. This analysis demonstrates how an understanding of population demography can be gained from structured population data even in a case where following marked individuals over their whole lifespan is not practical.
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An oral presentation about the use of clay models (i.e. replicas made in plasticine) to assess for potential predation on cave salamanders was presented at the 19th SEH European Congress of Herpetology, that was hels at the University of Salzburg in Austria (Salvidio et al., 2017). The pdf of this presentation has been added to the present project.
Interestingly, three other presentations were based on the use of clay models to test for predation on amphibians and reptiles. Presentations were on snakes (Stephenson et al., 2017), poison frogs (Preissler and Prohl, 2017) and harlequin toads (Rossler et al., 2017). The abstract book of the SEH Congress, containing these presentations and many more very interesting studies, can be downloaded from this website:
Have a good read,
Sebastiano
 
Sebastiano Salvidio
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Context. Concerns about conservation and ethics in amphibian research have been raised recently; therefore, non-lethal methods should always be preferred to investigate food habits in wild populations. However, there are no studies that compared the data obtained by different non-lethal dietary methods in amphibians. Aims. We compared the dietary habits obtained from stomach flushing, a method validated against stomach dissection, and faecal analysis on the same 31 individuals of the European plethodontid Speleomantes strinatii, a completely terrestrial salamander. Methods. After being stomach-flushed in the field, salamanders were kept in the laboratory at constant humidity and temperature to obtain faecal samples. Analyses comprised diversity and niche overlap indexes, as well as permutation, repeated-measures tests and graphical methods. Key results. Niche overlap between the two samples was low (O jk = 0.58) and prey diversity was significantly (P = 0.001) higher in stomach contents. There were also differences in the abundance of fly larvae, springtails and ants and the interpretation of the population trophic strategy varied according to the sampling method used. Key conclusions. Stomach flushing and faecal analysis gave different information, because, apparently, a differential prey degradation occurred. During the digestive process, ants became dominant, whereas springtails and fly larvae became under-represented in faecal samples. Therefore, on the basis of faecal analysis, diet diversity was underestimated and many individuals improperly appeared as ant-specialist feeders. Implications. In terrestrial salamanders, results from stomach flushing and faecal analysis should not be compared among studies, populations or species. Moreover, stomach flushing should always be preferred when assessing the trophic strategy and the role in food webs of salamanders. Additional keywords: amphibians, animal welfare, food habits, selective digestion.
Clay models are frequently used in ecological studies to estimate potential predation rates on small and cryptic vertebrates (Bateman et al. 2016). These models are easy to shape and they retain predator marks, allowing the identification of the body part attacked and of the predator. In herpetological studies, prey models are used to evaluate colour polymorphism, aposematism, mimicry and to assess differential predation rates in different habitats. Clay models have been applied in studies on both tailed and tailless amphibians in different geographic regions, with a first application in Europe by Velo-Antón & Cordero Rivera (2011). The present research aimed to evaluate by means of realistic clay models: i) if different potential predation rates were observed on the plethodontid salamander Speleomantes strinatii living in different habitats, and ii) if the presence of a brooding female reduced the potential predation of attended egg clutches, in comparison to unattended clutches. The results show that predators attacked the models significantly more (P < 0.01) in woodlands (43 attacked models out of 90) than inside caves (16 attacked model out of 94). Therefore, salamander populations inhabiting underground environments may benefit from reduced predation risk in comparison to forest-dwelling populations (Salvidio et al. 2017). Concerning the second experiment, similar predation rates on isolated eggs and on eggs attended by females were observed. This may suggest that all kind of models (i.e. eggs and/or salamanders) were not discriminated by the predators and attacked with similar frequencies.
Context. Concerns about conservation and ethics in amphibian research have been raised recently; therefore, non-lethal methods should always be preferred to investigate food habits in wild populations. However, there are no studies that compared the data obtained by different non-lethal dietary methods in amphibians. Aims. We compared the dietary habits obtained from stomach flushing, a method validated against stomach dissection, and faecal analysis on the same 31 individuals of the European plethodontid Speleomantes strinatii, a completely terrestrial salamander. Methods. After being stomach-flushed in the field, salamanders were kept in the laboratory at constant humidity and temperature to obtain faecal samples. Analyses comprised diversity and niche overlap indexes, as well as permutation, repeated-measures tests and graphical methods. Key results. Niche overlap between the two samples was low (O jk = 0.58) and prey diversity was significantly (P = 0.001) higher in stomach contents. There were also differences in the abundance of fly larvae, springtails and ants and the interpretation of the population trophic strategy varied according to the sampling method used. Key conclusions. Stomach flushing and faecal analysis gave different information, because, apparently, a differential prey degradation occurred. During the digestive process, ants became dominant, whereas springtails and fly larvae became under-represented in faecal samples. Therefore, on the basis of faecal analysis, diet diversity was underestimated and many individuals improperly appeared as ant-specialist feeders. Implications. In terrestrial salamanders, results from stomach flushing and faecal analysis should not be compared among studies, populations or species. Moreover, stomach flushing should always be preferred when assessing the trophic strategy and the role in food webs of salamanders.
Sebastiano Salvidio
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Estimating the abundance of Salamanders' populations and studying their demographic trends is a goal function, not only for understanding their ecology, but also to address proper conservation plans. In this paper we attempt to estimate the abundance and the density of a population of Speleomantes strinatii (Aellen, 1958), analysing spatially and temporally replicated count data with N-mixture models. e study was conducted on a Supra-Mediterranean mixed deciduous forest at an elevation of 900m a.s.l., where we selected 40 plots, each one measuring 12 m 2. In autumn 2013 all sites were visited five times, and the number of salamanders per site recorded. In addition, per each site, we measured some environmental features: the aspect of the slope (ASP), the distance from the nearest rock cliff (CLIFF), the presence of running water on the soil after forecasts (FLOOD). Also the relative humidity (RH) during the survey was measured. Data were analysed using N-mixture model in program PRESENCE; we built 24 models, accounting for constant or time dependent detectability, and abundance influenced by environmental covariates. e model with highest empirical support accounted for detection probability variation among surveys, and abundance of salamanders influenced by all covariates. In particular sites facing north had higher abundance of salamanders than those facing south. FLOOD and CLIFF both negatively influenced the abundance of Salamanders. e average estimated abundance of Salamanders per site is 7,1 (4,0 – 12,5; 95% confidence intervals) and the density estimated for the study area is 0,58 salamanders/m 2 (0,31 – 1,09; 95% confidence intervals). Riassunto. Stimare l'abbondanza delle popolazioni di urodeli e studiarne i cicli demogra-fici è di particolare importanza, non solo per comprendere la loro ecologia, ma anche per pianificare adeguate strategie di conservazione. Lo scopo di que-sto lavoro è quello di stimare l'abbondanza e la densità di una popolazione di Speleomantes strinatii (Aellen, 1958), mediante l'utilizzo di N-mixture models applicati a conteggi ripetuti. Lo studio è stato condotto in un bosco misto di Assessing salamanders abundance and density with N-mixture model: preliminary results on a Speleomantes strinatii (Aellen, 1958) population
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I am adding this short comment on abundance estimation of salamanders by repeated count of unmarked individuals, in the framework of occupancy and hierarchical modelling. This approach has been recently applied on North American forest salamanders by different authors, and also on European Plethodontid salamanders in Italy (Costa et al. 2016: Herpetological Conservation and Biology, 11: 344 - 349). These methods should be used when estimating local salamander abundance in relation to prey avialability or predation pressures. These methods were also suggested by Ficetola et al. (2016) for the Italian national survey of the continental species belonging to the genus Speleomantes.
 
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The utilization of food resources by a rock-face population of the plethodontid salamander Sprlromantes ambrosii was studied in northwestern Italy, both by dissection and stomach flushing. These two techniques proved quantitatively equivalent. S. ambrosii is an opportunistic feeder, preying on ground dwelling invertebrates within a broad range of groups and sizes. In addition, inorganic detritus, plant debris and salamander sloughed skin often are present in stomach contents. The utilization of prey taxa by number of specimens and by volume varies seasonally and between size classes, whereas prey volume spectra appear to remain constant within each size group. In mature individuals energy requirements are fulfilled mainly by large food items, whereas small prey are relatively more important in the diet of immature salamanders. Adults have a broader and a more varied trophic niche than juveniles. Values of trophic niche overlap are higher when calculated on prey volume categories than on taxonomic categories.
Sebastiano Salvidio
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In this paper we focus on the trophic strategy and intra-population diet variation of the larvae of the fire salamander, Salamandra salamandra gigliolii (Eiselt & Lanza, 1956), living in a fish-free freshwater habitat, in which they rank as top predators (Oberrisser & Waringer 2011). Even if data of the trophic ecology of S. salamandra larvae are available in the literature, they refer mainly to larvae inhabiting stagnant water bodies (Bressi et al. 1996, Reinhardt et al. 2013, but see Weitere et al. 2004 for data on stream-dwelling larvae). Therefore, our aims were (1) to identify the emerging trophic strategy of a stream population of S. salamandra larvae; (2) to assess prey selection, taking into account the availability of food resources in the environment; and (3) to test for the presence of trophic specialization at individual level and, if present, correlate it to individual body size.
Time series analysis has been used to evaluate the mechanisms regulating population dynamics of mammals and insects, but has been rarely applied to amphibian populations. In this study, the influence of endogenous (density-dependent) and exogenous (density-independent) factors regulating population dynamics of the terrestrial plethodontid salamander Speleomantes strinatii was analysed by means of time series and multiple regression analyses. During the period 1993-2005, S. strinatii population abundance, estimated by a standardised temporary removal method, displayed relatively low fluctuations, and the autocorrelation function (ACF) analysis showed that the time series had a noncyclic structure. The partial rate correlation function (PRCF) indicated that a strong first-order negative feedback dominated the endogenous dynamics. Stepwise multiple regression analysis showed that the only climatic factor influencing population growth rate was the minimum winter temperature. Thus, at least during the study period, endogenous, density-dependent negative feedback was the main factor affecting the growth rate of the salamander population, whereas stochastic environmental variables, such as temperature and rainfall, seemed to play a minor role in regulation. These results stress the importance of considering both exogenous and endogenous factors when analysing amphibian long-term population dynamics.
Animal populations living in the forest floor or in the soil may increase their fitness when colonizing shallow subterranean habitats. In fact in these habitats, animals will take advantage from more buffered environmental conditions, new ecological opportunities and lower levels of predation. However, while the first two conditions are well documented in the underground environment, the existence of lower levels of predation in the hypogean habitat was rarely assessed. The present research aimed to evaluate if different levels of potential predation pressure were present in different terrestrial habitats, in which the European cave salamander Speleomantes strinatii is found. This species is commonly found in the leaf litter along small streams and on moist rock faces, but is able to colonize also natural and artificial underground habitats. The experiment was conducted in Liguria (North-Western Italy) using salamander plasticine models. One hundred and ninety one cave salamander models were placed for six consecutive days to potential predators in six different locations inhabited by S. strinatii: three broadleaf woods and three artificial caves. No differences in the predation rate were observed between sites of the same habitat, but in broadleaf woods, a significantly higher predation on the models was observed when compared to those placed in the caves. These findings show that European cave salamander populations inhabiting hypogean environments may benefit from reduced predation risks in comparison to the nearby epigean ones.
Sebastiano Salvidio
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The adult sex ratio of a population of Speleomantes strinatii living in an underground habitat was studied for 12 consecutive years by temporal removal sampling. Capture probabilities of males (0.72) and females (0.69) were similar and yielded highly reliable sex ratio values. The adult sex ratio, expressed as the proportion of males, was significantly male-biased (mean 0.57, bootstrap 95% confidence intervals 0.53-0.65) and remained relatively constant during the study. A negative relationship was observed between adult sex ratio in one year and the abundance of juveniles in the following one (P=0.02), suggesting that an excess of males limited juvenile recruitment and therefore influenced population dynamics.
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Project goal
The objective of this project is to better understand the ecological role of salamanders both as predators and as prey. In particular, the habitat selection, population abundance and the feeding ecology of terrestrial salamanders will be analysed in different species and in different conspecific populations. Moreover, by using realistic clay models the predation pressure acting upon salamanders living in different habitats will also be assessed.
Background and motivation
Animals that colonize the underground environment increase their fitness for at least three reasons: (i) to avoid variable surface climatic conditions, (ii) to exploit new ecological niches and (iii) to reduce interactions with other species (i.e. competitors and/or predators).
To better understand the causes of the presence in shallow underground habitats of the endemic European plethodondid Speleomantes strinatii (Aellen, 1958), we used clay models as surrogates. Clay models permit the comparison of predation
rates observed in different environments and have been used to test potential predation in many different species and habitats.
The first results concerning terrestrial salamanders show that in woodlands, clay models are exposed to a four-time higher probability of being attacked in comparison to caves. Results and datasets are published in the recent paper by Salvidio, Palumbi, Romano and Costa (2017): "Safe caves and dangerous forests? Predation risk may contribute to salamander colonization of subterranean habitats" The Science of Nature 104: 20.
We are now extending the use of clay models to test more conditions and hypotheses on the potential predation on the cave salamander Speleomantes strinatii.
 
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Trophic niche may be the most important ecological dimension for some vertebrate groups and in particular for terrestrial amphibians, that are important predators of soil invertebrates. In general, resource partitioning occurs between syntopic species with similar ecological niches, and coexistence patterns seem to be regulated by temporal resource variability. However most of the generalization on foraging strategies of terrestrial salamanders are extrapolated from studies on New World temperate species, thus we investigated the seasonal effect of resource variation in an European forest ecosystem, in which two ecologically similar but phylogenetically distinct salamander species are found. The diet of adult and juvenile cave salamanders (Speleomantes strinati), and of adult spectacled salamander (Sala-mandrina perspicillata) was obtained by stomach flushing, and results showed large seasonal changes both in prey availability and in salamander realised trophic niche. Values of trophic diversity were similar and niche overlaps were large among all salamander groups in spring, during high prey availability. Conversely in autumn, when a two-fold reduction in prey biomass was observed, there was a clear niche partitioning as the smaller S. perspicillata shifted from a generalist to a specialized trophic strategy. Juvenile Speleomantes strinatii, that largely overlapped in size with S. perspicillata, did not show any change in diet, suggesting that the feeding strategies were species-specific and not size-mediated. The observed patterns of variation in feeding ecology indicate that similar predators may react differently to changing prey availability to enhance niche partitioning. We also observed an increased energy intake during autumn for S perspicillata and S. strinatii juveniles, possibly related to differences in microhabitat use and activity patterns. Ó 2012 Elsevier Masson SAS. All rights reserved.
Sebastiano Salvidio
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Animal populations living in the forest floor or in the soil may increase their fitness when colonizing shallow subterranean habitats. In fact in these habitats, animals will take advantage from more buffered environmental conditions, new ecological opportunities and lower levels of predation. However, while the first two conditions are well documented in the underground environment, the existence of lower levels of predation in the hypogean habitat was rarely assessed. The present research aimed to evaluate if different levels of potential predation pressure were present in different terrestrial habitats, in which the European cave salamander Speleomantes strinatii is found. This species is commonly found in the leaf litter along small streams and on moist rock faces, but is able to colonize also natural and artificial underground habitats. The experiment was conducted in Liguria (North-Western Italy) using salamander plasticine models. One hundred and ninety one cave salamander models were placed for six consecutive days to potential predators in six different locations inhabited by S. strinatii: three broadleaf woods and three artificial caves. No differences in the predation rate were observed between sites of the same habitat, but in broadleaf woods, a significantly higher predation on the models was observed when compared to those placed in the caves. These findings show that European cave salamander populations inhabiting hypogean environments may benefit from reduced predation risks in comparison to the nearby epigean ones.
Abstract: Information on individual trophic specialization may be relevant to better understand the ecological adaptation of populations to their environment and the evolution of their realized trophic niche. In this study, we analysed the trophic specialization at the individual level in a population of the plethodontid Northwest Italian Cave Salamander (Speleomantes strinatii (Aellen, 1958)), a terrestrial generalist predator. Salamanders were sampled in northwestern Italy on the forest floor in autumn (n = 49) and spring (n = 47) along with their available prey. In autumn, when trophic resources showed a twofold reduction in abundance, the population trophic niche width (TNW = 2.58) was significantly broader than during spring (TNW = 2.25), and in both seasons, individual specialization (IS) was significantly higher than expected by chance (P = 0.001). There were no sexual or ontogenetic differences in IS within each season, but IS in autumn was significantly higher than in spring (IS = 0.34 and IS = 0.41, respectively; P = 0.01). These findings are in accordance with the niche variation hypothesis, which predicts a positive relationship between TNW and IS. Therefore, while the population became more generalist, individual salamanders shifted towards a more specialized diet by adapting their feeding behaviour to changes in prey availability.
Sebastiano Salvidio
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Information on individual trophic specialization may be relevant to better understand the ecological adaptation of populations to their environment and the evolution of their realized trophic niche. In this study, we analysed the trophic specialization at the individual level in a population of the plethodontid Northwest Italian Cave Salamander (Speleomantes strinatii (Aellen, 1958)), a terrestrial generalist predator. Salamanders were sampled in northwestern Italy on the forest floor in autumn (n = 49) and spring (n = 47) along with their available prey. In autumn, when trophic resources showed a twofold reduction in abundance, the population trophic niche width (TNW = 2.58) was significantly broader than during spring (TNW = 2.25), and in both seasons, individual specialization (IS) was significantly higher than expected by chance (P = 0.001). There were no sexual or ontogenetic differences in IS within each season, but IS in autumn was significantly higher than in spring (IS = 0.34 and IS = 0.41, respectively; P = 0.01). These findings are in accordance with the niche variation hypothesis, which predicts a positive relationship between TNW and IS. Therefore, while the population became more generalist, individual salamanders shifted towards a more specialized diet by adapting their feeding behaviour to changes in prey availability.
Sebastiano Salvidio
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The study of trophic ecology of terrestrial salamanders is central for a better understanding of their adaptability and dispersal, in particular in Mediterranean ecosystems where their feeding activity is reduced because of prolonged arid periods. Terrestrial salamanders are generalist predators that feed on a large array of invertebrate prey groups, however, there are few studies comparing the feeding strategy and the trophic specialization at the individual level in conspecific populations of salamanders living in different habitats. In this study, two populations of the Sardinian endemic salamander Speleomantes imperialis were sampled in areas characterized by different climate, vegetation and geological substrate. Dietary habits, obtained by stomach flushing, and physiological condition, assessed through a body condition index, were analysed and compared between populations. The two populations displayed different diets on the basis of the taxonomic composition of prey categories, but both of them behaved as generalist predators and shared a similar body condition index. Moreover, in both populations the indices of individual trophic specialization were significantly different from null models assuming a random prey distribution among predators. Therefore, the two populations were largely composed by individually specialized salamanders. Overall, these findings are in good agreement with other studies on the trophic ecology of top predators and in particular of terrestrial salamanders. The realized trophic strategies, i.e. generalist at the population and specialist at the individual level, were highly consistent eographically and the two populations exploited the different arrays of prey found in their environments similarly.
Andrea Costa
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Recent studies suggest that many organisms actively colonize the subterranean environment to avoid climatic stress, exploit new ecological opportunities and reduce competition and predation. Terrestrial salamanders are known to colonize the more stable subterranean habitats mainly to escape external climatic extremes, while the role of predation avoidance remains untested. To better understand the importance of predation, we used clay models of the cave salamander Speleomantes strinatii to compare the predation occurring in woodland and subterranean habitats. Models were positioned in three forests and in three caves in NW Italy. One-hundred eighty-four models were retrieved from the field and 59 (32%) were attacked by predators. Models were attacked on their head more often than expected by chance and, therefore, were perceived by predators as real prey items. In the woodlands, clay models showed a four-time higher probability of being attacked in comparison to caves, suggesting a different level of potential predation risk in these surface habitats. These findings are one of the first experimental evidences that, in terrestrial ecosystems, predation avoidance may contribute to the salamander underground colonization process. -------AVAILABLE AT THE FOLLOWING LINK----------- http://www.readcube.com/articles/10.1007/s00114-017-1443-y?author_access_token=2cNdj4e_fh4Lh9QS4fd0jfe4RwlQNchNByi7wbcMAY5jaTtEnhO7sWsr64hIvhHkKEPVPQlr3jzy2mylCrgwHTggBAasUrKQO5p6hc1X7XRuCmmlDEuF4JInqzDgTAx0-gFXxEO-0iyjKt5y8DD7cA%3D%3D
Sebastiano Salvidio
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The objective of this project is to better understand the ecological role of salamanders both as predators and as prey. In particular, the habitat selection, population abundance and the feeding ecology of terrestrial salamanders will be analysed in different species and in different conspecific populations. Moreover, by using realistic clay models the predation pressure acting upon salamanders living in different habitats will also be assessed.