Independent and Competing Disease Risks: Implications for Host Populations in Variable Environments

Jolles, Anna E.; Etienne, Rampal S.; Olff, Han

doi:10.1086/503055

Cited by 30 publications

(35 citation statements)

References 69 publications

(57 reference statements)

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“…There are examples from the animal disease literature illustrating synergy, antagonistic, and neutral population-level interactions among competing pathogens (Rohani et al 2003, Jolles et al 2006, 2008. Results from the present study indicate an apparently neutral impact of E. maimaiga on the density dependence of LdNPV in North American gypsy moth populations.…”

Section: Discussionmentioning

confidence: 47%

Emergent fungal entomopathogen does not alter density dependence in a viral competitor

Liebhold

Plymale

Elkinton

et al. 2013

Ecology

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Abstract. Population cycles in forest Lepidoptera often result from recurring densitydependent epizootics of entomopathogens. While these systems are typically dominated by a single pathogen species, insects are often infected by multiple pathogens, yet little is known how pathogens interact to affect host dynamics. The apparent invasion of northeastern North America by the fungal entomopathogen Entomophaga maimaiga some time prior to 1989 provides a unique opportunity to evaluate such interactions. Prior to the arrival of E. maimaga, the oscillatory dynamics of host gypsy moth, Lymantria dispar, populations were apparently driven by epizootics of a nucleopolyhedrovirus. Subsequent to its emergence, E. maimaiga has caused extensive mortality in host populations, but little is known about how it has altered multigenerational dynamics of the gypsy moth and its virus. Here we compared demographic data collected in gypsy moth populations prior to vs. after E. maimaiga's invasion. We found that the recently invading fungal pathogen virtually always causes greater levels of mortality in hosts than does the virus, but fungal mortality is largely density independent. Moreover, the presence of the fungus has apparently not altered the gypsy mothvirus density-dependent interactions that were shown to drive periodic oscillations in hosts before the arrival of the fungus.

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Section: Discussionmentioning

confidence: 47%

Emergent fungal entomopathogen does not alter density dependence in a viral competitor

Liebhold

Plymale

Elkinton

et al. 2013

Ecology

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“…Pathogens can reduce host density and, in some cases, drive their host populations to extinction (McCallum and Dobson 1995;Tompkins and Begon 1999;De Castro and Bolker 2005;Jolles et al 2006). Paradoxically, many populations suffering from a variety of infectious diseases are relatively stable (Albon et al 2002;Caley et al 2002;Krkosek et al 2011;Tobler et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Disease-induced mortality causes host population declines only if it is additive to other sources of host mortality (i.e. competition or predation; Anderson and May 1979;Burnham and Anderson 1984;Tompkins et al 2002;Jolles et al 2006). In contrast, when mortality is compensatory, increases in disease-induced deaths are balanced by a reduction in natural mortality from other causes (Tompkins and Begon 1999;Lebreton 2005;Jolles et al 2006), and populations will remain stable.…”

Section: Introductionmentioning

confidence: 99%

“…competition or predation; Anderson and May 1979;Burnham and Anderson 1984;Tompkins et al 2002;Jolles et al 2006). In contrast, when mortality is compensatory, increases in disease-induced deaths are balanced by a reduction in natural mortality from other causes (Tompkins and Begon 1999;Lebreton 2005;Jolles et al 2006), and populations will remain stable. The distinction between additive and compensatory mortality effects of pathogens is important to conservation biologists because it describes the difference between declining and stable populations (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Infection dynamics in frog populations with different histories of decline caused by a deadly disease

et al. 2015

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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.

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“…However, a study specifically testing this assumption found it to be flawed (Freeman and Morgan, 1992). Other examples of key 24 ecological assumptions that have been found to be erroneous when empirically tested include: (1) that disease acts independently of other mortality-causing factors in mammal epidemiological models (tested by Jolles et al, 2006); (2) that a "typical" age structure can be applied to fish populations to accurately assess densitydependent productivity effects (tested by Zabel and Levin, 2002) and (3) that island communities are more 28 susceptible to biological invasion than continental landmasses (tested by Sol, 2000). Importantly, the use, whether implicit or explicit, of such erroneous assumptions reduces the validity of the research results predicated upon them (Thompson, 2002).…”

Section: Introductionmentioning

confidence: 99%

Are nest sites actively chosen? Testing a common assumption for three non-resource limited birds

2009

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DisclaimerThe University of Gloucestershire has obtained warranties from all depositors as to their title in the material deposited and as to their right to deposit such material.The University of Gloucestershire makes no representation or warranties of commercial utility, title, or fitness for a particular purpose or any other warranty, express or implied in respect of any material deposited.The University of Gloucestershire makes no representation that the use of the materials will not infringe any patent, copyright, trademark or other property or proprietary rights.The University of Gloucestershire accepts no liability for any infringement of intellectual property rights in any material deposited but will remove such material from public view pending investigation in the event of an allegation of any such infringement. PLEASE SCROLL DOWN FOR TEXT.This is a peer-reviewed, post-print (final draft post-refereeing) version of the following published document: Goodenough DisclaimerThe University of Gloucestershire has obtained warranties from all depositors as to their title in the material deposited and as to their right to deposit such material.The University of Gloucestershire makes no representation or warranties of commercial utility, title, or fitness for a particular purpose or any other warranty, express or implied in respect of any material deposited.The University of Gloucestershire makes no representation that the use of the materials will not infringe any patent, copyright, trademark or other property or proprietary rights.The University of Gloucestershire accepts no liability for any infringement of intellectual property rights in any material deposited but will remove such material from public view pending investigation in the event of an allegation of any such infringement. Many widely-accepted ecological concepts are simplified assumptions about complex situations, which remain largely untested. One example is the assumption that nest-building species actively choose nest sites when they are not resource limited: an assumption that has seen little direct empirical testing as most studies 4 on nest-site selection start with the assumption that individuals choose nest sites actively, rather than simply by chance. We used 15 years of data from a nestbox scheme in the UK to test the assumption of active nestsite choice in three bird species that differ in breeding and migratory strategy: blue tit (Cyanistes caeruleus), great tit (Parus major) and pied flycatcher (Ficedula hypoleuca). Nest-site selection was non-random 8 (implying active nest-site choice) for blue and great tits, but not for pied flycatchers. We also considered the relative importance of year-specific and site-specific factors in determining occupation of nest sites. Sitespecific factors were more important than year-specific factors for the tit species, while the reverse was true for pied flycatchers. Our results show that nest site selection, in birds at least, is not always the result of 12 active choice and thus that active choice ...

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Independent and Competing Disease Risks: Implications for Host Populations in Variable Environments

Cited by 30 publications

References 69 publications

Emergent fungal entomopathogen does not alter density dependence in a viral competitor

Emergent fungal entomopathogen does not alter density dependence in a viral competitor

Infection dynamics in frog populations with different histories of decline caused by a deadly disease

Are nest sites actively chosen? Testing a common assumption for three non-resource limited birds

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