Unexpected Rarity of the Pathogen Batrachochytrium dendrobatidis in Appalachian Plethodon Salamanders: 1957–2011

Abstract

Widespread population declines in terrestrial Plethodon salamanders occurred by the 1980s throughout the Appalachian Mountains, the center of global salamander diversity, with no evident recovery. We tested the hypothesis that the historic introduction and spread of the pathogenic fungus Batrachochytrium dendrobatidis (Bd) into the eastern US was followed by Plethodon population declines. We expected to detect elevated prevalence of Bd prior to population declines as observed for Central American plethodontids. We tested 1,498 Plethodon salamanders of 12 species (892 museum specimens, 606 wild individuals) for the presence of Bd, and tested 94 of those for Batrachochytrium salamandrivorans (Bs) and for ranavirus. Field samples were collected in 2011 from 48 field sites across a 767 km transect. Historic samples from museum specimens were collected at five sites with the greatest number and longest duration of collection (1957–987), four of which were sampled in the field in 2011. None of the museum specimens were positive for Bd, but four P. cinereus from field surveys were positive. The overall Bd prevalence from 1957–2011 for 12 Plethodon species sampled across a 757 km transect was 0.2% (95% CI 0.1–0.7%). All 94 samples were negative for Bs and ranavirus. We conclude that known amphibian pathogens are unlikely causes for declines in these Plethodon populations. Furthermore, these exceptionally low levels of Bd, in a region known to harbor Bd, may indicate that Plethodon specific traits limit Bd infection.

Antifungal Bacteria on Woodland Salamander Skin Exhibit High Taxonomic Diversity and Geographic Variability

“…PCR conditions were 95°C for 8 min, followed by 30 cycles of 95°C for 45 s, 52°C for 30 s, and 72°C for 30 s and a final extension (72°C for 3 min). We followed the sequencing methods outlined by Muletz et al (37) to sequence the cleaned PCR products. Individual sequences were assembled and edited in Sequencher 5.1 to obtain a consensus sequence per anti-B.…”

“…dendrobatidis bacteria on three Plethodon species at three localities and along an elevational gradient in the central Appalachian Mountains. We chose Plethodon salamanders because previous sampling had indicated a low prevalence of B. dendrobatidis even though B. dendrobatidis often occurs on other amphibians in the region (37). This contrasts with widespread population declines caused by B. dendrobatidis in closely related plethodontid salamanders in Central America (38).…”

Averting a North American biodiversity crisis

“…North America is the world's salamander biodiversity hotspot with 48% of 676 recognized salamander species representing 9 of the 10 known families within the order Caudata (190 species in the United States, 137 in Mexico, and 21 in Canada) ( 8). Bsal has not been reported in North America, although few studies have been published in the short time since Bsal was described ( 9,10).…”

Concurrent Infection of Batrachochytrium dendrobatidis and Ranavirus among Native Amphibians from Northeastern Oklahoma, USA

“…; Muletz et al. ). This could be the result of a much larger sample size or larger geographic area of disease screening, or perhaps the incidence of simultaneous infections is more common than we are aware (Warne et al.…”

“…Moreover, Muletz et al. () found no incidence of concurrent Bd and RV infection in the plethodontid taxa they sampled (genera Desmognathus , Eurycea , and Plethodon ), even in areas where Bd infection rates were high in other amphibians.…”