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Widespread occurrence of Batrachochytrium dendrobatidis in contemporary and historical samples of the endangered Bombina pachypus along the Italian peninsula.

Canestrelli D, Zampiglia M, Nascetti G - PLoS ONE (2013)

Bottom Line: This temporal mismatch between pathogen occurrence and host decline, as well as the spatial pattern of the declines, suggests that the pathogen has not acted as a "lone killer", but in conjunction with other factors.Among the potentially interacting factors, we identified two as the most probable, genetic diversity of host populations and recent climate changes.We discuss the plausibility of this scenario and its implications on the conservation of B. pachypus populations.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Viterbo, Italy. canestrelli@unitus.it

ABSTRACT
Batrachochytrium dendrobatidis is considered a main driver of the worldwide declines and extinctions of amphibian populations. Nonetheless, fundamental questions about its epidemiology, including whether it acts mainly as a "lone killer" or in conjunction with other factors, remain largely open. In this paper we analysed contemporary and historical samples of the endangered Apennine yellow-bellied toad (Bombina pachypus) along the Italian peninsula, in order to assess the presence of the pathogen and its spreading dynamics. Once common throughout its range, B. pachypus started to decline after the mid-1990s in the northern and central regions, whereas no declines have been observed so far in the southern region. We show that Batrachochytrium dendrobatidis is currently widespread along the entire peninsula, and that this was already so at least as early as the late 1970s, that is, well before the beginning of the observed declines. This temporal mismatch between pathogen occurrence and host decline, as well as the spatial pattern of the declines, suggests that the pathogen has not acted as a "lone killer", but in conjunction with other factors. Among the potentially interacting factors, we identified two as the most probable, genetic diversity of host populations and recent climate changes. We discuss the plausibility of this scenario and its implications on the conservation of B. pachypus populations.

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Geographic distribution of the 15 sampled populations of Bombina pachypus.The inset shows the species range along the Italian peninsula.
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pone-0063349-g001: Geographic distribution of the 15 sampled populations of Bombina pachypus.The inset shows the species range along the Italian peninsula.

Mentions: We analysed 136 individuals of B. pachypus from 15 sampling sites (17 samples, as two sites were sampled in two different years), 8 in the northern and central portion of the peninsula (sites 1 to 8; 82 individuals overall) and 7 from the Calabria region (southern Italy; sites 9 to 15; 54 individuals overall). Sampling sessions were carried out from late April to mid June. Sampling locations - spanning the entire Apennine peninsula -, as well as the number of individuals sampled at each site and year are presented in Table 1 and Figure 1. Among the tested individuals, 56 were collected during a sampling campaign carried out between 1978 and 1981 (38 were from Calabria and 18 were from populations located more to the north), while the remaining 80 samples were drawn between 2003 and 2012 (16 were from Calabria and 64 were from populations located more to the north).


Widespread occurrence of Batrachochytrium dendrobatidis in contemporary and historical samples of the endangered Bombina pachypus along the Italian peninsula.

Canestrelli D, Zampiglia M, Nascetti G - PLoS ONE (2013)

Geographic distribution of the 15 sampled populations of Bombina pachypus.The inset shows the species range along the Italian peninsula.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646936&req=5

pone-0063349-g001: Geographic distribution of the 15 sampled populations of Bombina pachypus.The inset shows the species range along the Italian peninsula.
Mentions: We analysed 136 individuals of B. pachypus from 15 sampling sites (17 samples, as two sites were sampled in two different years), 8 in the northern and central portion of the peninsula (sites 1 to 8; 82 individuals overall) and 7 from the Calabria region (southern Italy; sites 9 to 15; 54 individuals overall). Sampling sessions were carried out from late April to mid June. Sampling locations - spanning the entire Apennine peninsula -, as well as the number of individuals sampled at each site and year are presented in Table 1 and Figure 1. Among the tested individuals, 56 were collected during a sampling campaign carried out between 1978 and 1981 (38 were from Calabria and 18 were from populations located more to the north), while the remaining 80 samples were drawn between 2003 and 2012 (16 were from Calabria and 64 were from populations located more to the north).

Bottom Line: This temporal mismatch between pathogen occurrence and host decline, as well as the spatial pattern of the declines, suggests that the pathogen has not acted as a "lone killer", but in conjunction with other factors.Among the potentially interacting factors, we identified two as the most probable, genetic diversity of host populations and recent climate changes.We discuss the plausibility of this scenario and its implications on the conservation of B. pachypus populations.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Viterbo, Italy. canestrelli@unitus.it

ABSTRACT
Batrachochytrium dendrobatidis is considered a main driver of the worldwide declines and extinctions of amphibian populations. Nonetheless, fundamental questions about its epidemiology, including whether it acts mainly as a "lone killer" or in conjunction with other factors, remain largely open. In this paper we analysed contemporary and historical samples of the endangered Apennine yellow-bellied toad (Bombina pachypus) along the Italian peninsula, in order to assess the presence of the pathogen and its spreading dynamics. Once common throughout its range, B. pachypus started to decline after the mid-1990s in the northern and central regions, whereas no declines have been observed so far in the southern region. We show that Batrachochytrium dendrobatidis is currently widespread along the entire peninsula, and that this was already so at least as early as the late 1970s, that is, well before the beginning of the observed declines. This temporal mismatch between pathogen occurrence and host decline, as well as the spatial pattern of the declines, suggests that the pathogen has not acted as a "lone killer", but in conjunction with other factors. Among the potentially interacting factors, we identified two as the most probable, genetic diversity of host populations and recent climate changes. We discuss the plausibility of this scenario and its implications on the conservation of B. pachypus populations.

Show MeSH