Geographic distribution of the chytrid pathogen Batrachochytrium dendrobatidis among mountain amphibians along the Italian peninsula

Abstract

The amphibian chytrid pathogen Batrachochytrium dendrobatidis (Bd) is considered a major cause of amphibian population declines, particularly in montane areas. Here, we investigated the presence and distribution of Bd among populations of 3 mid- to high-altitude species spanning the entire Italian peninsula (486 individuals from 39 sites overall): the stream frog Rana italica, the fire salamander Salamandra salamandra gigliolii, and the alpine newt Mesotriton alpestris apuanus. We found Bd in all of the analyzed species. Despite the widespread distribution of the pathogen, its overall prevalence (6, 9 and 19%, respectively) was lower than previously reported for the endangered Apennine yellow-bellied toad Bombina pachypus (62.5%). Moreover, several populations of the species studied here were not infected, even at sites where Bd has been detected in other host species. When coupled with the lack of evidence for Bd-related mortalities in these species in peninsular Italy, these results suggest that mechanisms of resistance and/or tolerance are protecting populations of these species from the pathogenic activity of Bd. Nevertheless, in light of the dynamic pattern of Bd-host interactions reported in other studies, of Bd-related mortalities in at least 1 study species (S. s. salamandra) in other areas, and the ongoing climate changes in montane environments, we suggest that the occurrence of Bd should be considered a potential threat to the long-term persistence of these species, and urge the implementation of monitoring and conservation plans.

Emerging infectious disease threats to European herpetofauna

“…This combined effect of peptide defence and varying Bd strains show that at least for now, some species of European amphibians are protected against the potentially negative effects of Bd outbreaks (Fisher et al, 2009). BATRACHOCHYTRIUM SALAMANDRIVORANS Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011Ohst et al, 2013Ohst et al, 2011Ohst et al, 2011Ohst et al, 2011 Garner et al, 2006Stagni et al, 2004Adams et al, 2008Simoncelli et al, 2005Stagni et al, 2002(in Bovero et al, 2008) Garner et al, 2004(in Bovero et al, 2008) Zampiglia et al, 2013Grasseli et al, 2019Zampiglia et al, 2013Zampiglia et al, 2013Bovero et al, 2008Bielby et al, 2009 The salamander chytrid fungus (Batrachochytrium salamandrivorans, hereafter Bsal) was first identified in 2013 after a dramatic loss of European fire salamanders (Salamandra salamandra) in the Netherlands (Martel et al, 2013;Spitzen-van der Sluijs et al, 2013). The fungus itself is closely related to B. dendrobatidis, having diverged sometime in the late Cretaceous or early Paleogene (Martel et al, 2014).…”

Drilling Down Hotspots of Intraspecific Diversity to Bring Them Into On-Ground Conservation of Threatened Species

“…Skin swabs were collected from 105 individuals collected in 15 sites (Figure 1). Genomic DNA was extracted from swabs following the protocol of Boyle et al (2004) as modified by Zampiglia et al (2013). The molecular diagnostic assay was conducted in 25 µl reaction volumes using a nested PCR protocol as developed by Goka et al (2009).…”

“…Third, our results showed a drastic reduction of the geographic occurrence of the chytrid pathogen on its B. pachypus host, if compared to what was observed in the recent past (Canestrelli et al, 2013), but they do not imply pathogen decline in the area, since we did not analyze the whole range of its potential hosts in southern Italy. Thus, monitoring its occurrence in situ both in B. pachypus and other potential hosts (Simoncelli et al, 2005;Zampiglia et al, 2013), as well as within environmental matrices, will be a mandatory step of in situ actions, as will be also a proper prophylaxis in ex situ programs.…”

Drilling down hotspots of intraspecific diversity to bring them into on-ground conservation of threatened species

“…Third, our results showed a drastic reduction of the geographic occurrence of the chytrid pathogen on its B. pachypus host, if compared to what observed in the recent past , but they do not imply pathogen decline in the area. Thus, monitoring its occurrence in situ both in B.pachypus and other potential hosts (Simoncelli et al, 2005;Zampiglia et al, 2013), as well as within environmental matrices, will be a mandatory step of in situ actions, as will be also a proper prophylaxis in ex situ programs.…”