Papers by Robert Puschendorf
Biotropica, Jan 1, 2005
We surveyed the population status of the Neotropical toad genus Atelopus, and document recent cat... more We surveyed the population status of the Neotropical toad genus Atelopus, and document recent catastrophic declines that are more severe than previously reported for any amphibian genus. Of 113 species that have been described or are candidates for description, data indicate that in 42 species, population sizes have been reduced by at least half and only ten species have stable populations. The status of the remaining taxa is unknown. At least 30 species have been missing from all known localities for at least 8 yr and are feared extinct. Most of these species were last seen between 1984 and 1996. All species restricted to elevations of above 1000 m have declined and 75 percent have disappeared, while 58 percent of lowland species have declined and 38 percent have disappeared. Habitat loss was not related to declines once we controlled for the effects of elevation. In fact, 22 species that occur in protected areas have disappeared. The fungal disease Batrachochytrium dendrobatidis has been documented from nine species that have declined, and may explain declines in higher elevation species that occur in undisturbed habitats. Climate change may also play a role, but other potential factors such as environmental contamination, trade, and introduced species are unlikely to have affected more than a handful of species. Widespread declines and extinctions in Atelopus may reflect population changes in other Neotropical amphibians that are more difficult to survey, and the loss of this trophic group may have cascading effects on other species in tropical ecosystems.
Journal of Animal Ecology, 2016
1.Pathogens can be critical drivers of the abundance and distribution of wild animal populations.... more 1.Pathogens can be critical drivers of the abundance and distribution of wild animal populations. The presence of an over-dispersed pathogen load distribution between hosts (where few hosts harbor heavy parasite burdens and light infections are common) can have an important stabilizing effect on host-pathogen dynamics where infection intensity determines pathogenicity. This may potentially lead to endemicity of an introduced pathogen rather than extirpation of the host and/or pathogen. 2.Over-dispersed pathogen load distributions have rarely been considered in wild animal populations as an important component of the infection dynamics of microparasites such as bacteria, viruses, protozoa and fungi. 3.Here we examined the abundance, distribution and transmission of the model fungal pathogen Batrachochytrium dendrobatidis (Bd, cause of amphibian chytridiomycosis) between wild-caught Litoria rheocola (common mist frogs) to investigate the effects of an over-dispersed pathogen load distribution on the host population in the wild. We quantified host survival, infection incidence and recovery probabilities relative to infectious burden, and compared the results of models where pathogen over-dispersion either was or was not considered an important feature of host-pathogen dynamics. 4.We found the distribution of Bd load between hosts to be highly over-dispersed. We found that host survival was related to infection burden, and that accounting for pathogen over-dispersion allowed us to better understand infection dynamics and their implications for disease control. In addition, we found that the pattern of host infections and recoveries varied markedly with season whereby (i) infections established more in winter, consistent with temperature dependent effects on fungal growth, and (ii) recoveries (loss of infection) occurred frequently in the field throughout the year but were less likely in winter. 5.Our results suggest that pathogen over-dispersion is an important feature of endemic chytridiomycosis, and that intensity of infection determines disease impact. These findings have important implications for our understanding of chytridiomycosis dynamics and the application of management strategies for disease mitigation. We recommend quantifying individual infectious burdens rather than infection state where possible in microparasitic diseases. This article is protected by copyright. All rights reserved.
The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence... more The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence is regularly observed, directional shifts in virulence are less commonly observed and are typically associated with decreasing virulence of biological control agents through coevolution. It is increasingly appreciated, however, that spatial effects can lead to evolutionary trajectories that differ from standard expectations. One such possibility is that, as a pathogen spreads through a naive host population, its virulence increases on the invasion front. In Central America, there is compelling evidence for the recent spread of pathogenic Batrachochytrium dendrobatidis (Bd) and for its strong impact on amphibian populations. Here, we re-examine data on Bd prevalence and amphibian population decline across 13 sites from southern Mexico through Central America, and show that, in the initial phases of the Bd invasion, amphibian population decline lagged approximately 9 years behind the arrival of the pathogen, but that this lag diminished markedly over time. In total, our analysis suggests an increase in Bd virulence as it spread southwards, a pattern consistent with rapid evolution of increased virulence on Bd's invading front. The impact of Bd on amphibians might therefore be driven by rapid evolution in addition to more proximate environmental drivers.
Science, 2014
Undercover. Many Alpheidae shrimps live deep in the reef and are impossible to collect nonlethally.
Journal of Applied Ecology, 2011
1. Correlative species distribution models can be used to produce spatially explicit estimates of... more 1. Correlative species distribution models can be used to produce spatially explicit estimates of environmental suitability for organisms. This process can provide meaningful information for a range of purposes (e.g. estimating a species' current or future distribution, estimating dispersal limits, predicting occupancy for conservation planning) but, like all statistical exercises, is subject to numerous assumptions and can be influenced by several sources of potential bias. 2. In this issue of Journal of Applied Ecology, we (Murray et al. 2011) employ a correlative species distribution model for infection with the pathogen Batrachochytrium dendrobatidis (Bd), cause of amphibian chytridiomycosis, to derive useful information for the immediate management and research of this pathogen in Australia. Also in this issue, Rohr, Halstead & Raffel (2011) comment on some of the potential limitations of our approach and the value of our results in practice.
Diversity and Distributions, 2012
Page 1. BIODIVERSITY RESEARCH Where are the survivors? Tracking relictual populations of endanger... more Page 1. BIODIVERSITY RESEARCH Where are the survivors? Tracking relictual populations of endangered frogs in Costa Rica Adrián Garcıa-Rodrıguez1,2*, Gerardo Chaves1, Catalina Benavides-Varela3,4 and Robert Puschendorf5 INTRODUCTION ...
Naturalist, 2007
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Herpetological Review., 2005
Resumen: Amphibian declines in pristine and apparently undisturbed habitats have occurred in many... more Resumen: Amphibian declines in pristine and apparently undisturbed habitats have occurred in many highland areas in tropical Latin America (Young et al. 2001. Cons. Biol. 15: 1213-1223). One member of the Eleutherodactylus" rugulosus group" is E. ranoides. Known from lowlands and premontane slopes from eastern Nicaragua to extreme western Panama, it was previously common in the Area de Conservación Guanacaste in northwestern Costa Rica. In at least two herpetological surveys of the same area in 2001 ...
We describe a new glassfrog belonging to the genus Hyalinobatrachium from the tropical wet forest... more We describe a new glassfrog belonging to the genus Hyalinobatrachium from the tropical wet forests and premontane rainforests of the Caribbean foothills of Costa Rica, at elevations between 400-800 m. The type locality is approximately 4km west of Santa Clara, ca. 400 m a.s.l. (N 10.219, W 83.949). This new taxon is distinguished by its morphological characteristics, distinct advertisement call, and genetic distance (COI mRNA). The new species can be distinguished from other species of the genus Hyalinobatrachium by the combination of the following characters: (1) snout truncate in dorsal and lateral views; (2) granular dorsal skin; (3) parietal and cardial peritonea transparent; (4) hand webbing formula III 2 --2 + IV; (5) in life having a uniform lime green dorsal surface that lacks any evident light or dark spots; (6) iris coloration silvery-white with fine dark spots or reticulation; (7) advertisement call consisting of a single tonal long metallic whistlelike note with a duration of 0.40-0.55 s (average 0.501 s) and a dominant frequency of 3.35-3.44 kHz (average 3.39 kHz); (8) highly divergent DNA sequences for the mitochondrial gene COI from other analysed members of the genus Hyalinobatrachium, with 12.4% divergence from its closest known species, Hyalinobatrachium chirripoi.
Undercover. Many Alpheidae shrimps live deep in the reef and are impossible to collect nonlethally.
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Papers by Robert Puschendorf