Ché Weldon

Ché Weldon
North-West University | NWU ·  Unit for Environmental Sciences and Management

PhD

About

83
Publications
22,352
Reads
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3,457
Citations
Citations since 2016
32 Research Items
2049 Citations
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Introduction
I work with the null hypothesis that amphibians worldwide have an ancient association with parasitic chytrids, and that replacement of endemic lineages is occurring as a lineage (BdGPL) invades and exhibits aggressive infectivity and hypervirulence after invasion. We use comparative phylogenetic methods to understand the origin of a particular strain of the fungus, BdCAPE and its related lineages, and experimentally determine how changes in rates of evolution have led to variation in virulence.
Additional affiliations
May 2007 - present
North-West University
Position
  • I teach animal physiology to undergrad students and subjects such as biomonitoring, biogeography and conservation ecology to post-grad students in Environmental Science. My research focusses on the role of amphibian disease on the conservation biology of amphibians in Africa and Madagascar.
Education
February 2001 - November 2004
North-West University
Field of study
  • Zoology

Publications

Publications (83)
Preprint
Full-text available
Outbreaks of emerging infectious diseases are trained by local biotic and abiotic factors, with host declines occurring when conditions favour the pathogen. Extinction of the Tanzanian Kihansi spray toad (Nectophrynoides asperginis) in 2004 was contemporaneous with the construction of a dam, implicating habitat modification in the loss of this spec...
Article
Nasal drug administration has been identified as a potential alternative to oral drug administration, especially for systemic delivery of large molecular weight compounds. Major advantages of nasal drug delivery include high vascularity and permeability of the epithelial membranes as well as circumvention of first-pass metabolism. RPMI 2650 cell la...
Article
Full-text available
Accurate survey methods are required for any wildlife research to yield reliable population data. This constraint finds significance in amphibian research that involves a highly threatened group of animals with a large proportion of cryptic species not easily detected by conventional survey methods. Across a growing spectrum of zoology research, su...
Article
Full-text available
The ability to detect and monitor infectious disease in a phylogenetically informative manner is critical for their management. Phylogenetically informative diagnostic tests enable patterns of pathogen introduction or changes in the distribution of genotypes to be measured, enabling research into the ecology of the pathogen. Batrachochytrium dendro...
Preprint
Full-text available
The ability to detect and monitor infectious disease in a phylogenetically informative manner is critical for their management. Phylogenetically informative diagnostic tests enable patterns of pathogen introduction or changes in the distribution of genotypes to be measured, enabling research into the ecology of the pathogen. Batrachochytrium dendro...
Article
History has shown that pandemics can have major impacts on populations and the environment. The current Covid-19 pandemic is turning the world upside down, and will undoubtedly leave its footprints on all sectors of life to some degree. The infection pathway and high infection rate of this causative virus affect our social lives, and even our behav...
Article
Full-text available
Introduction : The nasal route of drug administration offers an alternative way for oral drug delivery and has the benefit of avoiding first-pass metabolism through drug delivery directly into the systemic circulation. The drug absorption enhancing effects of selected aloe leaf materials have been shown across various delivery routes, but their eff...
Article
Full-text available
The Kihansi spray toad, Nectophrynoides asperginis, became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Previous investigations have indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the...
Article
The Kihansi spray toad, Nectophrynoides asperginis, became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Previous investigations have indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the...
Article
Full-text available
Lambert et al . question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm th...
Article
The fruit from various pepper plants has been employed for the seasoning of food, as perfuming agents, and also as traditional medicines. Phytochemicals isolated from different pepper species have been found to modulate the pharmacokinetics of orally administered drugs. This study investigated the possibility to apply capsaicin and piperine (extrac...
Preprint
Full-text available
The Kihansi spray toad, Nectophrynoides asperginis , became extinct in the wild despite population monitoring and conservation management of its habitat in the Kihansi gorge, Tanzania. Anecdotal evidence has indicated human induced habitat modification, predators, pesticides and disease as possible causes of a rapid population decline and the speci...
Article
Full-text available
The demise of amphibians? Rapid spread of disease is a hazard in our interconnected world. The chytrid fungus Batrachochytrium dendrobatidis was identified in amphibian populations about 20 years ago and has caused death and species extinction at a global scale. Scheele et al. found that the fungus has caused declines in amphibian populations every...
Data
This PDF file includes: Materials and Methods - Figs. S1, S3, S4, S6, S7, and S9 to S16 - Tables S2 to S5 - Captions for figs. S2, S5, and S8 - Caption for table S1 - Captions for data S1 to S3 - References
Article
Full-text available
Amphibian populations worldwide are at risk of extinction from infectious diseases, including chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Amphibian cutaneous microbiomes interact with Bd and can confer protective benefits to the host. The composition of the microbiome itself is influenced by many environment-...
Article
Full-text available
Parasitic chytrid fungi have emerged as a signifcant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modifed a pre-existing protocol for isolating chytrids f...
Article
Full-text available
Panzootic chytrid fungus out of Asia Species in the fungal genus Batrachochytrium are responsible for severe declines in the populations of amphibians globally. The sources of these pathogens have been uncertain. O'Hanlon et al. used genomics on a panel of more than 200 isolates to trace the source of the frog pathogen B. dendrobatidis to a hyperdi...
Preprint
Full-text available
Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into sterile culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating...
Article
The fungal pathogen Batrachochytrium dendrobatidis has caused declines and extinctions in hundreds of amphibian species across the world. Virulence varies among and within lineages; the Global Panzootic Lineage (GPL) is the most pathogenic, although there is also variation in lethality among GPL isolates. Amphibians have a number of defences agains...
Article
Full-text available
For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd) has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virule...
Article
Full-text available
The Infectious disease chytridiomycosis, which is caused by the fungal pathogen Batrachochytrium dendrobatidis, has been identified as one of the most important drivers of amphibian declines and extinction. In vitro B. dendrobatidis is susceptible to a range of disinfectants, but not all have been tested on animals and some that have been proven ef...
Article
Full-text available
Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amp...
Article
According to the threat-sensitivity hypothesis, prey avoidance behaviour should reflect the magnitude of predation risk. Since predation can strongly affect reproduction success, ovipositing females are expected to adaptively adjust their predator-avoidance response, or local breeding patch selectivity, in accordance with the perceived level of thr...
Article
Full-text available
A recent paper by Kolby et al. [1], surveying for Batrachochytrium dendrobatidis (Bd) and ranavirus in Madagascar, presents results for 508 amphibian specimens and 68 water bodies sampled during a 2-month period of the 2013-14 wet season. Kolby et al. [1] did not detect Bd in any of the samples, presenting evidence that add to our understanding of...
Technical Report
Full-text available
The conservation of Madagascar amphibians has become object of study and application in the last twenty years, and concomitant to the presence and action of several herpetologists, who take this discipline to Madagascar, and highlighted the importance of preparing a serious action plan. Until then, taxonomy and survey works were the main activities...
Article
Full-text available
Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd 's first record i...
Conference Paper
Full-text available
Evidence-based conservation is a relatively new approach being used to streamline relevant knowledge, improve effectiveness and support decision making in conservation management. Several Conservation Evidence synopses have been compiled for various species groups and habitats, aimed at providing conservation practitioners, scientists and policymak...
Article
Full-text available
The use of diatoms in the conservation management of Hewitt's ghost frog Distribution patterns of diatoms were investigated to determine the impact of shading on diatoms, which form the main diet of the endangered frog species, Heleophryne hewitti. Although diatom community composition is influenced by shade coverage, it does not affect tadpole gra...
Article
Full-text available
Abstract.*Amphibians are threatened globally by the chytridiomycete fungus Batracho- chytrium dendrobatidis (Bd), which is still expanding in range. Madagascar, rich in amphibian diversity, remains one of the few places that the fungus has not invaded. Herein, we present results from a pilot survey for Bd in conjunction with a rapid amphibian surve...
Article
Full-text available
Chytridiomycosis has been identified as a major cause of global amphibian declines. Despite widespread evidence of Batrachochytrium dendrobatidis infection in South African frogs, sampling for this disease has not focused on threatened species, or whether this pathogen poses a disease risk to these species. This study assessed the occurrence of Bd-...
Article
The elygium is a darkly pigmented projection over the pupil of the tadpoles of certain species that live mostly at high altitudes. It has been suggested that this structure shades the retina, protecting it from high UV levels. In post-metamorphic individuals, the elygium is replaced by a structure known as an umbraculum. Confusion arose in the past...
Article
Full-text available
Amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has been hypothesised to be an indigenous parasite of African amphibians. In Cameroon, however, previous surveys in one region (in the northwest) failed to detect this pathogen, despite the earliest African Bd having been recorded from a frog in eastern Cameroon, plus one recent record in...
Article
Full-text available
A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from...
Data
List of West African caecilian and anuran species tested for the presence of Bd , and their main ecological characters. (PDF)
Data
List of study areas, their geographic positions as well as details of sampling and analysis for each sample. (XLS)
Data
Full-text available
Details of the variable contributions to the calculated ENMs. (PDF)
Data
Full-text available
List of positive African Bd records. (PDF)
Article
Full-text available
Hewitt se spookpadda(Heleophryne hewitti), is ‘n bedreigde spesie wat slegs in vier strome vandie Elandsberge voorkom. Die totale area van besetting vanH. hewittiis binne die grense van ‘n bosbou plantasie.
Article
Full-text available
Madagascar harbors a rich and diverse amphibian fauna, with over 280 nominal species of native frogs, all of which are endemic to the island. Although many species are threatened predominantly by habitat destruction, so far this fauna has not experienced any enigmatic declines as amphibians have in other parts of the globe. The amphibian chytrid fu...
Article
Full-text available
Batrachochytrium dendrobatidis (Bd) is a globally ubiquitous fungal infection that has emerged to become a primary driver of amphibian biodiversity loss. Despite widespread effort to understand the emergence of this panzootic, the origins of the infection, its patterns of global spread, and principle mode of evolution remain largely unknown. Using...
Article
Morphological similarities between the tadpoles of Amietia umbraculata and A. vertebralis have led to confusion and incorrect descriptions and identifications in the literature. Based on 33 body measurements and ratios we revised the morphological descriptions of the tadpoles of the two species. Tadpole identification was verified through DNA seque...
Article
Full-text available
Morphological similarities between the tadpoles of Amietia umbraculata and A. vertebralis have led to confusion and incorrect descriptions and identifications in the literature. Based on 33 body measurements and ratios we revised the morphological descriptions of the tadpoles of the two species. Tadpole identification was verified through DNA seque...
Article
Full-text available
Environmental parameters such as temperature and rainfall influence the biology of amphibians and are likely to similarly influence the growth and prevalence of associated pathogens. Amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), causes an infectious disease, chytridiomycosis, in amphibians worldwide. Field studies on post-metamorph...
Article
Full-text available
Environmental parameters such as temperature and rainfall influence the biology of amphibians and are likely to similarly influence the growth and prevalence of associated pathogens. Amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), causes an infectious disease, chytridiomycosis, in amphibians worldwide. Field studies on post-metamorph...
Article
Full-text available
The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis, is enigmatic because it occurs globally in both declining and apparently healthy (non-declining) amphibian populations. This distribution has fueled debate concerning whether, in sites where it has recently been found, the pathogen was introduced or is endemic. In this s...
Data
Coding scheme for the multilocus sequence typing markers and genotype matrix of global population. (0.02 MB TXT)
Data
Full-text available
Genealogical network depicting relatedness among multilocus genotypes of Bd. The network was estimated using the software TCS 1.21 on a distance matrix calculated using “hetequal” coding of alleles (see Materials and Methods section). Each branch represents a single mutational or recombinational step. Ancestral intermediate genotypes not observed i...
Article
Full-text available
http://www.plosbiology.org/article/info:doi%2F10.1371%2Fjournal.pbio.0060118
Article
Full-text available
The global fungal disease chytridiomycosis can have catastrophic effects on amphibian populations leading to declines and even extinctions. Madagascar with its highly endemic and diverse amphibians is particularly vulnerable to emerging infectious diseases. In this study we report on a histological survey of chytridiomycosis at multiple localities...
Article
Full-text available
We comment on the results of a previous study which evaluate the accuracy of mouthpart depigmentation as an indicator of Batrachochytrium dendrobatidis (Bd) infection in anuran larvae. Macroscopic mouthpart inspection is a useful technique for Bd identification since it is practical and nonlethal; however, this method is also expected to result in...
Conference Paper
The fungal pathogen of amphibians, (Batrachochytrium dendrobatidis, or Bd) is widespread in southern Africa, yet Bd is not known to have caused population declines and is only rarely associated with amphibian mortality. Because B. dendrobatidis-associated mortality events are rare in southern Africa, their study may help us identify biotic or abiot...
Article
Full-text available
Harvesting wild amphibians for animal trade and consequent introductions of exotic species are considered threats to biodiversity. For this study, we evaluated the literature and unpublished data on Xenopus laevis exports from the Western Cape, South Africa, since the onset of the trade in the early 1930s. Exports for medical science have changed f...
Article
Full-text available
The fungal pathogen Batrachochytrium dendrobatidis contributes to the global decline of amphibians. Although mortality from B. dendrobatidis infections occurs primarily in postmetamorphic individuals, infected tadpoles may suffer reduced growth and developmental rates as a result of oral chytridiomycosis, possibly affecting adult fitness. We conduc...
Article
Full-text available
The ability to quantify infections provides a tool with which to perform comparative pathological research. The need exists for a simplistic standard method to compare infection levels of Batrachochytrium dendrobatidis, a major cause of global amphibian declines. Through examination of skin sloughs of the Cape river frog Afrana fuscigula, we presen...
Article
Full-text available
Stopping further global losses of amphibian populations and species requires an unprecedented conservation response.