From The Cover: Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community

Department of Zoology, Southern Illinois University, Carbondale, 62901-6501, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2006; 103(9):3165-70. DOI: 10.1073/pnas.0506889103
Source: PubMed


Pathogens rarely cause extinctions of host species, and there are few examples of a pathogen changing species richness and diversity of an ecological community by causing local extinctions across a wide range of species. We report the link between the rapid appearance of a pathogenic chytrid fungus Batrachochytrium dendrobatidis in an amphibian community at El Copé, Panama, and subsequent mass mortality and loss of amphibian biodiversity across eight families of frogs and salamanders. We describe an outbreak of chytridiomycosis in Panama and argue that this infectious disease has played an important role in amphibian population declines. The high virulence and large number of potential hosts of this emerging infectious disease threaten global amphibian diversity.

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Available from: Cynthia Carey, Oct 13, 2015
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    • "One disease, chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis, has been proposed as a leading cause of amphibian population declines (Rachowicz et al. 2006). Although other factors, including habitat destruction, invasive species, climate change, and chemical contamination , play active roles in amphibian declines, chytridiomycosis has been implicated in large-scale population declines in some regions (Lips et al. 2006; Rachowicz et al. 2006; Skerratt et al. 2007). Fitness costs from B. dendrobatidis exposure are likely greatest in metamorphic and adult amphibians, because B. dendrobatidis infects keratinized cells (Berger et al. 1998). "
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    ABSTRACT: Effects of pathogens on host life-history characteristics can be influenced by changes in the immune system that occur during development as well as by environmental factors that negatively affect immune system function. Amphibians worldwide are experiencing population declines from chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis. Disease outbreaks can be influenced by timing of exposure to B. dendrobatidis and by abiotic factors, such as pesticides, that could influence susceptibility. To examine the effects of larval pesticide exposure and timing of B. dendrobatidis exposure during development, we exposed Cope’s Gray Treefrogs (Hyla chrysoscelis) to the insecticide malathion throughout larval development and to B. dendrobatidis at 1 or 3 wk posthatching, or after metamorphosis. We reared tadpoles through metamorphosis and then for 28 d in the terrestrial environment to examine treatment effects on larval survival, time to metamorphosis, and mass at metamorphosis, as well as terrestrial survival and growth after metamorphosis. We found that malathion exposure resulted in a decrease in mass at metamorphosis and a decrease in terrestrial growth. Exposure to B. dendrobatidis did not influence larval development, terrestrial growth, or survival, and exposure to malathion appears to not have altered the effects of B. dendrobatidis exposure in a biologically significant way.
    Herpetologica 09/2015; 71(3). DOI:10.1655/HERPETOLOGICA-D-13-00070 · 1.14 Impact Factor
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    • "Severe Bd infections disrupt cutaneous function , causing an imbalance in electrolyte transport across the epidermis, which leads to asystolic cardiac arrest (Voyles et al. 2009). Chytridiomycosis can cause extinctions because Bd has a broad host range, including both larval and adult amphibians, some of which are resistant to its effects and act as reservoirs for the pathogen (Brunner et al. 2004; Retallick et al. 2004; Lips et al. 2006; Murray et al. 2009; Sapsford 2012). The presence of reservoirs for the fungal pathogen greatly increases the potential for extinction from disease. "
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    ABSTRACT: Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8 %) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.
    Oecologia 08/2015; DOI:10.1007/s00442-015-3422-3 · 3.09 Impact Factor
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    • "The rapid and ongoing reduction of herp species richness worldwide has added urgency to efforts to understand the ecological roles that they play within ecosystems (Stuart et al. 2004, Lips et al. 2006, Connelly et al. 2011). "
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    ABSTRACT: Amphibians and reptiles (herps) are the most abundant and diverse vertebrate taxa in tropical ecosystems. Nevertheless, little is known about their role in maintaining and regulating ecosystem functions and, by extension, their potential value for supporting ecosystem services. Here, we review research on the ecological functions of Neotropical herps, in different sources (the bibliographic databases, book chapters, etc.). A total of 167 Neotropical herpetology studies published over the last four decades (1970 to 2014) were reviewed, providing information on more than 100 species that contribute to at least five categories of ecological functions: i) nutrient cycling; ii) bioturbation; iii) pollination; iv) seed dispersal, and; v) energy flow through ecosystems. We emphasize the need to expand the knowledge about ecological functions in Neotropical ecosystems and the mechanisms behind these, through the study of functional traits and analysis of ecological processes. Many of these functions provide key ecosystem services, such as biological pest control, seed dispersal and water quality. By knowing and understanding the functions that perform the herps in ecosystems, management plans for cultural landscapes, restoration or recovery projects of landscapes that involve aquatic and terrestrial systems, development of comprehensive plans and detailed conservation of species and ecosystems may be structured in a more appropriate way. Besides information gaps identified in this review, this contribution explores these issues in terms of better understanding of key questions in the study of ecosystem services and biodiversity and, also, of how these services are generated.
    Universitas Scientiarum 08/2015; 20(2):229-245. DOI:10.11144/Javeriana.SC20-2.efna
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