What shapes the trophic niche of European plethodontid salamanders?

Abstract

The trophic niche is a life trait that identifies the consumer’s position in a local food web. Several factors, such as ontogeny, competitive ability and resource availability contribute in shaping species trophic niches. To date, information on the diet of European Hydromantes salamanders are only available for a limited number of species, no dietary studies have involved more than one species of the genus at a time, and there are limited evidences on how multiple factors interact in determining diet variation. In this study we examined the diet of multiple populations of six out of the eight European cave salamanders, providing the first data on the diet for five of them. In addition, we assessed whether these closely related generalist species show similar diet and, for each species, we tested whether season, age class or sex influence the number and the type of prey consumed. Stomach condition (empty/full) and the number of prey consumed were strongly related to seasonality and to the activity level of individuals. Empty stomachs were more frequent in autumn, in individuals far from cave entrance and in juveniles. Diet composition was significantly different among species. Hydromantes imperialis and H. supramontis were the most generalist species; H. flavus and H. sarrabusensis fed mostly on Hymenoptera and Coleoptera Staphylinidae, while H. genei and H. ambrosii mostly consumed Arachnida and Endopterygota larvae. Furthermore, we detected seasonal shifts of diet in the majority of the species examined. Conversely, within each species, we did not find diet differences between females, males and juveniles. Although being assumed to have very similar dietary habits, here Hydromantes species were shown to be characterized by a high divergence in diet composition and in the stomach condition of individuals.

Are the Neglected Tipuloidea Crane Flies (Diptera) an Important Component for Subterranean Environments?

“…For example the cave salamanders of the genus Hydromantes Gistel, 1848, catch their prey darting their protrusible tongue [70,71]; therefore, if they target a dense aggregation of dipterans they could even catch multiple individuals with one "shot". In fact, crane flies are the most abundant prey of European cave salamanders [72]. A second advantage is given by location.…”

Transgressive niche across a salamander hybrid zone revealed by microhabitat analyses

“…Second, we compared body condition index (BCI) among individuals observed in different areas of caves, to assess the potential advantages of selecting specific sectors. Sectors close to the cave entrance are generally more rich in prey (Ficetola et al, ; Lunghi, Cianferoni, Ceccolini, Veith, et al, ) and we expect that they are associated with higher BCI. Our study highlights how selecting transgressive microhabitats can affect the fate of hybrid zones.…”

“…Second, we compared body condition index (BCI) among individuals observed in different areas of caves, to assess the potential advantages of selecting specific sectors. Sectors close to the cave entrance are generally more rich in prey (Ficetola et al, 2018;Lunghi, Cianferoni, Ceccolini, Veith, et al, 2018a) and…”

Photographic database of the European cave salamanders, genus Hydromantes

“…During the last few decades several studies have shed light on some life history traits of Hydromantes, such as the reproductive behaviour, trophic niche and population dynamics [14][15][16][17] . However, to collect data on these species can be extremely complex.…”