Varying Responses of Northeastern North American Amphibians to the Chytrid Pathogen <i>Batrachochytrium dendrobatidis</i>

Gahl, Megan K.; Longcore, Joyce E.; Houlahan, Jeff E.

doi:10.1111/j.1523-1739.2011.01801.x

Cited by 94 publications

(98 citation statements)

References 34 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We chose American toad metamorphs in this study because they are sensitive to Bd in the laboratory (Gahl, Longcore, & Houlahan, 2012; Wise, Rumschlag, & Boone, 2014) and are infected with Bd in natural populations (Longcore, Longcore, Pessier, & Halteman, 2007; Richards‐Hrdlicka, Richardson, & Mohabir, 2013), which makes this species an ideal model organism for assessing variation in Bd isolates’ virulence across environmental conditions. We predicted that isolates from California and Panama would be more virulent than Ohio and Maine, having stronger effects on host growth and survival.…”

Section: Introductionmentioning

confidence: 99%

Host size influences the effects of four isolates of an amphibian chytrid fungus

Burrow

Rumschlag

Boone

2017

Ecology and Evolution

View full text Add to dashboard Cite

Understanding factors that influence host–pathogen interactions is key to predicting outbreaks in natural systems experiencing environmental change. Many amphibian population declines have been attributed to an amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). While this fungus is widespread, not all Bd‐positive populations have been associated with declines, which could be attributed to differences in pathogen virulence or host susceptibility. In a laboratory experiment, we examined the effects of Bd isolate origin, two from areas with Bd‐associated amphibian population declines (El Copé, Panama, and California, USA) and two from areas without Bd‐related population declines (Ohio and Maine, USA), on the terrestrial growth and survival of American toad (Anaxyrus americanus) metamorphs reared in larval environments with low or high intraspecific density. We predicted that (1) Bd isolates from areas experiencing declines would have greater negative effects than Bd isolates from areas without declines, and (2) across all isolates, growth and survival of smaller toads from high‐density larval conditions would be reduced by Bd exposure compared to larger toads from low‐density larval conditions. Our results showed that terrestrial survival was reduced for smaller toads exposed to Bd with variation in the response to different isolates, suggesting that smaller size increased susceptibility to Bd. Toads exposed to Bd gained less mass, which varied by isolate. Bd isolates from areas with population declines, however, did not have more negative effects than isolates from areas without recorded declines. Most strikingly, our study supports that host condition, measured by size, can be indicative of the negative effects of Bd exposure. Further, Bd isolates’ impact may vary in ways not predictable from place of origin or occurrence of disease‐related population declines. This research suggests that amphibian populations outside of areas experiencing Bd‐associated declines could be impacted by this pathogen and that the size of individuals could influence the magnitude of Bd's impact.

show abstract

Section: Introductionmentioning

confidence: 99%

Host size influences the effects of four isolates of an amphibian chytrid fungus

Burrow

Rumschlag

Boone

2017

Ecology and Evolution

View full text Add to dashboard Cite

show abstract

“…More recently, it has been suggested that L. pipiens may be a ''carrier'' species (Woodhams et al 2008;Gahl et al 2011), as it is currently not known to exhibit acute symptoms or mortality when infected by Bd. In a recent study of an endangered population of L. pipiens in British Columbia, Bd is thought to have swept through in an epidemic fashion leading to rapid declines and endangerment of that population (Voordouw et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Fitness Consequences of Infection by Batrachochytrium dendrobatidis in Northern Leopard Frogs (Lithobates pipiens)

et al. 2013

View full text Add to dashboard Cite

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been linked to amphibian declines and extinctions worldwide. The pathogen has been found on amphibians throughout eastern North America, but has not been associated with mass die-offs in this region. In this study, we conducted laboratory experiments on the effects of Bd infection in a putative carrier species, Lithobates pipiens, using two estimators of fitness: jumping performance and testes morphology. Over the 8-week study period, peak acceleration during jumping was not significantly different between infected and uninfected animals. Peak velocity, however, was significantly lower for infected animals after 8 weeks. Two measures of sperm production, germinal epithelium depth, and maximum spermatic cyst diameter, showed no difference between infected and uninfected animals. The width, but not length, of testes of infected animals was significantly greater than in uninfected animals. This study is the first to show effects on whole-organism performance of Bd infection in post-metamorphic amphibians, and may have important long-term, evolutionary implications for amphibian populations co-existing with Bd infection.

show abstract

“…In contrast, the wood frog L. sylvaticus can die from chytridiomycosis at young post-metamorphic stages under laboratory conditions (Searle et al 2011, Gahl et al 2012. We used bullfrogs and wood frogs as representative species with low and high mortality risk for chytridiomycosis, respectively.…”

Section: Introductionmentioning

confidence: 99%

Host invasion by Batrachochytrium dendrobatidis: fungal and epidermal ultrastructure in model anurans

Greenspan¹,

Longcore²,

Calhoun³

2012

Dis. Aquat. Org.

View full text Add to dashboard Cite

The chytridiomycete fungus Batrachochytrium dendrobatidis (Bd) colonizes mouthparts of amphibian larvae and superficial epidermis of post-metamorphic amphibians, causing the disease chytridiomycosis. Fungal growth within host cells has been documented by light and transmission electron microscopy; however, entry of the fungus into host cells has not. Our objective was to document how Bd enters host cells in the wood frog Lithobates sylvaticus, a species at high mortality risk for chytridiomycosis, and the bullfrog L. catesbeianus, a species at low mortality risk for chytridiomycosis. We inoculated frogs and documented infection with transmission electron microscopy. Zoospores encysted on the skin surface and produced morphologically similar germination tubes in both host species that penetrated host cell membranes and enabled transfer of zoospore contents into host cells. Documenting fungal and epidermal ultrastructure during host invasion furthers our understanding of Bd development and the pathogenesis of chytridiomycosis. KEY WORDS: Chytridiomycosis · Morphology · Transmission electron microscopy · Lithobates catesbeianus · Lithobates sylvaticus Resale or republication not permitted without written consent of the publisherDis Aquat Org 100: [201][202][203][204][205][206][207][208][209][210] 2012 scopically, excessive skin sloughing, lethargy, anorexia, loss of righting reflex, and abnormal posture may be observed (Nichols et al. 2001, Daszak et al. 2004) but often not until immediately before death (Bradley et al. 2002, Parker et al. 2002. Proximate cause of death is inhibition of electrolyte transport across epidermis and subsequent disruption of cardiac electrical activity (Voyles et al. 2009).The asexual life cycle of Bd consists of a motile zoospore stage and a stationary thallus stage (Berger et al. 2005). Zoospores are flagellated and are not bounded by a cell wall. After a motile period, usually lasting ≤24 h, a zoospore encysts (i.e. attaches to a substrate, retracts the flagellum, and forms a wall of chitin around the spore body). Morphology after encystment depends on substrate type. On nutrient media, an encysted zoospore develops into a single or colonial (internally divided) zoosporangium (endogenous growth); root-like rhizoids originating from 1 or more points on the zoosporangium may be numerous . In an amphibian host, cellular contents of a superficially encysted zoospore leave the cyst and enter a host cell (exogenous growth), inside which a single or colonial zoosporangium develops; rhizoids are usually less abundant than on nutrient media (Berger et al. 2005). The specifics of amphibian host invasion by Bd (i.e. the morphological process by which zoospore contents are transferred from a cyst into a host cell) have not been reported. In other chytrid species with known developmental morphologies (saprophytes and patho gens of plants, algae, protists, and invertebrates), endobiotic (i.e. intracellular) growth of a thallus is initiated when a protrusion of the zoospore cyst wall e...

show abstract

Varying Responses of Northeastern North American Amphibians to the Chytrid Pathogen Batrachochytrium dendrobatidis

Cited by 94 publications

References 34 publications

Host size influences the effects of four isolates of an amphibian chytrid fungus

Host size influences the effects of four isolates of an amphibian chytrid fungus

Fitness Consequences of Infection by Batrachochytrium dendrobatidis in Northern Leopard Frogs (Lithobates pipiens)

Host invasion by Batrachochytrium dendrobatidis: fungal and epidermal ultrastructure in model anurans

Contact Info

Product

Resources

About