Condition-dependent reproductive effort in frogs infected by a widespread pathogen

Roznik, Elizabeth A.; Sapsford, Sarah J.; Pike, David A.; Schwarzkopf, Lin; Alford, Ross A.

doi:10.1098/rspb.2015.0694

Cited by 30 publications

(44 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have no a priori reason to suspect higher emigration in uninfected frogs or in those with high zoospore burdens compared with those having low burdens (Roznik et al . ). Rather, frogs appeared to maintain calling territories on the stream year‐round suggesting site fidelity (Phillott et al .…”

Section: Discussionmentioning

confidence: 97%

Endemicity of chytridiomycosis features pathogen overdispersion

Grogan

Phillott

Scheele

et al. 2016

Journal of Animal Ecology

View full text Add to dashboard Cite

Pathogens can be critical drivers of the abundance and distribution of wild animal populations. The presence of an overdispersed pathogen load distribution between hosts (where few hosts harbour 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. Overdispersed 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. 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 overdispersed 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 overdispersion either was or was not considered an important feature of host-pathogen dynamics. We found the distribution of Bd load between hosts to be highly overdispersed. We found that host survival was related to infection burden and that accounting for pathogen overdispersion 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. Our results suggest that pathogen overdispersion 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.

show abstract

Section: Discussionmentioning

confidence: 97%

Endemicity of chytridiomycosis features pathogen overdispersion

Grogan

Phillott

Scheele

et al. 2016

Journal of Animal Ecology

View full text Add to dashboard Cite

show abstract

“…Indeed, previous studies have demonstrated that testes of Bd-infected frogs are larger and contain more sperm than those of uninfected controls [18]. Furthermore, Bd-infected males, when in good condition, are more likely than uninfected males to be callers [19].…”

Section: Discussionmentioning

confidence: 99%

“…Infection risk may be further heightened during mating, as hormonal changes can induce temporary immunosuppression [21]. While social contact seems unlikely to be the primary mode by which the disease spreads [19], H. japonica is a largely terrestrial species so females are unlikely to be exposed to Bd zoospores in standing water except when ovipositing. Whether Bd directly acts on hosts to increase calling behaviour, thereby effectively promoting its own spread, requires further study.…”

Section: Discussionmentioning

confidence: 99%

Enhanced call effort in Japanese tree frogs infected by amphibian chytrid fungus

An¹,

Waldman²

2016

Biol. Lett.

View full text Add to dashboard Cite

Some amphibians have evolved resistance to the devastating disease chytridiomycosis, associated with global population declines, but immune defences can be costly. We recorded advertisement calls of male Japanese tree frogs (Hyla japonica) in the field. We then assessed whether individuals were infected by Batrachochytrium dendrobatidis (Bd), the causal agent of the disease. This allowed us to analyse call properties of males as a function of their infection status. Infected males called more rapidly and produced longer calls than uninfected males. This enhanced call effort may reflect pathogen manipulation of host behaviour to foster disease transmission. Alternatively, increased calling may have resulted from selection on infected males to reproduce earlier because of their shortened expected lifespan. Our results raise the possibility that sublethal effects of Bd alter amphibian life histories, which contributes to long-term population declines.

show abstract

“…Parasites are usually assumed to be deleterious for their hosts [26,27], and have typically been linked to hosts with poor body condition (e.g. [27,28]).…”

Section: Introductionmentioning

confidence: 99%

“…[27,28]). Body condition is a key parameter for fisheries management [29,30], as it can act as a proxy for predicting future fish growth and reproductive success [31].…”

Section: Introductionmentioning

confidence: 99%

Body Condition Peaks at Intermediate Parasite Loads in the Common Bully Gobiomorphus cotidianus

Maceda‐Veiga¹,

Green²,

Poulin³

et al. 2016

PLoS ONE

View full text Add to dashboard Cite

Most ecologists and conservationists perceive parasitic infections as deleterious for the hosts. Their effects, however, depend on many factors including host body condition, parasite load and the life cycle of the parasite. More research into how multiple parasite taxa affect host body condition is required and will help us to better understand host-parasite coevolution. We used body condition indices, based on mass-length relationships, to test the effects that abundances and biomasses of six parasite taxa (five trematodes, Apatemon sp., Tylodelphys sp., Stegodexamene anguillae, Telogaster opisthorchis, Coitocaecum parvum, and the nematode Eustrongylides sp.) with different modes of transmission have on the body condition of their intermediate or final fish host, the common bully Gobiomorphus cotidianus in New Zealand. We used two alternative body condition methods, the Scaled Mass Index (SMI) and Fulton’s condition factor. General linear and hierarchical partitioning models consistently showed that fish body condition varied strongly across three lakes and seasons, and that most parasites did not have an effect on the two body condition indices. However, fish body condition showed a highly significant humpbacked relationship with the total abundance of all six parasite taxa, mostly driven by Apatemon sp. and S. anguillae, indicating that the effects of these parasites can range from positive to negative as abundance increases. Such a response was also evident in models including total parasite biomass. Our methodological comparison supports the SMI as the most robust mass-length method to examine the effects of parasitic infections on fish body condition, and suggests that linear, negative relationships between host condition and parasite load should not be assumed.

show abstract

Condition-dependent reproductive effort in frogs infected by a widespread pathogen

Cited by 30 publications

References 47 publications

Endemicity of chytridiomycosis features pathogen overdispersion

Endemicity of chytridiomycosis features pathogen overdispersion

Enhanced call effort in Japanese tree frogs infected by amphibian chytrid fungus

Body Condition Peaks at Intermediate Parasite Loads in the Common Bully Gobiomorphus cotidianus

Contact Info

Product

Resources

About