Introduction: Ecological impact of parasitism on wildlife host populations

Parasitology ◽  
1995 ◽  
Vol 111 (S1) ◽  
pp. S3-S14 ◽  
Author(s):  
B. T. Grenfell ◽  
F. M. D. Gulland
Keyword(s):  
Population Dynamics ◽  
Potential Role ◽  
Evolutionary Ecology ◽  
Ecological Impact ◽  
Natural Populations ◽  
Parasite Population ◽  
Theoretical Studies ◽  
Host Parasite

The study of parasite population dynamics has been one of the major developments in ecology over the last 15 years (Kennedy, 1975). The seminal articles of Crofton (1971) and Anderson & May (1978, 1979; May & Anderson, 1978, 1979) began this process by illustrating the potential role of parasites in regulating or destabilizing the dynamics of wildlife host populations. Since then, a variety of empirical and theoretical studies (reviewed by Grenfell & Dobson, 1995) have explored the role of parasites in natural populations. In parallel with these population dynamical developments, a growing interest in the evolutionary ecology of parasites has also led to a large literature, examining the evolutionary impact of parasites and the importance of host-parasite coevolution (Hamilton, 1982; May & Anderson, 1990; Lively & Apanius, 1995; Read et al. 1995; Herre, this volume).

scholarly journals Causation without correlation: parasite-mediated frequency-dependent selection and infection prevalence

2021 ◽  
Author(s):  
Curtis M Lively ◽  
Julie Xu ◽  
Frida Ben-Ami
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Infection Prevalence ◽  
Strong Positive Correlation ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Host Diversity ◽  
Host Genetic ◽  
Host Parasite

Parasite-mediated selection is thought to maintain host genetic diversity for resistance. We might thus expect to find a strong positive correlation between host genetic diversity and infection prevalence across natural populations. Here we used computer simulations to examine host-parasite coevolution in 20 simi-isolated clonal populations across a broad range of values for both parasite virulence and parasite fecundity. We found that the correlation between host genetic diversity and infection prevalence can be significantly positive for intermediate values of parasite virulence and fecundity. But the correlation can also be weak and statistically non-significant, even when parasite-mediated frequency-dependent selection is the sole force maintaining host diversity. Hence correlational analyses of field populations, while useful, might underestimate the role of parasites in maintaining host diversity.

scholarly journals Maternal effects alter the severity of inbreeding depression in the offspring

2016 ◽  
Vol 283 (1838) ◽  
pp. 20161023 ◽  
Author(s):  
Natalie Pilakouta ◽  
Per T. Smiseth
Keyword(s):  
Maternal Effects ◽  
Inbreeding Depression ◽  
Potential Role ◽  
Causal Effect ◽  
Natural Populations ◽  
Larval Survival ◽  
Burying Beetle ◽  
Nicrophorus Vespilloides ◽  
Selection For

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreeding depression in the offspring. Inbreeding depression is a reduction in the fitness of inbred offspring relative to outbred offspring. Here, we tested whether maternal effects due to body size alter the magnitude of inbreeding depression in the burying beetle Nicrophorus vespilloides . We found that inbreeding depression in larval survival was more severe for offspring of large females than offspring of small females. This might be due to differences in how small and large females invest in an inbred brood because of their different prospects for future breeding opportunities. To our knowledge, this is the first evidence for a causal effect of the maternal phenotype on the severity of inbreeding depression in the offspring. In natural populations that are subject to inbreeding, maternal effects may drive variation in inbreeding depression and therefore contribute to variation in the strength and direction of selection for inbreeding avoidance.

scholarly journals Melanin-based coloration and host–parasite interactions under global change

2018 ◽  
Vol 285 (1879) ◽  
pp. 20180285 ◽  
Author(s):  
J. Côte ◽  
A. Boniface ◽  
S. Blanchet ◽  
A. P. Hendry ◽  
J. Gasparini ◽  
...  
Keyword(s):  
Global Change ◽  
Potential Role ◽  
Disease Risk ◽  
Multiple Stressors ◽  
Colour Polymorphism ◽  
Host Parasite Interactions ◽  
To Come ◽  
Colour Morphs ◽  
Host Parasite

The role of parasites in shaping melanin-based colour polymorphism, and the consequences of colour polymorphism for disease resistance, remain debated. Here we review recent evidence of the links between melanin-based coloration and the behavioural and immunological defences of vertebrates against their parasites. First we propose that (1) differences between colour morphs can result in variable exposure to parasites, either directly (certain colours might be more or less attractive to parasites) or indirectly (variations in behaviour and encounter probability). Once infected, we propose that (2) immune variation between differently coloured individuals might result in different abilities to cope with parasite infection. We then discuss (3) how these different abilities could translate into variable sexual and natural selection in environments varying in parasite pressure. Finally, we address (4) the potential role of parasites in the maintenance of melanin-based colour polymorphism, especially in the context of global change and multiple stressors in human-altered environments. Because global change will probably affect both coloration and the spread of parasitic diseases in the decades to come, future studies should take into account melanin-based coloration to better predict the evolutionary responses of animals to changing disease risk in human-altered environments.

Effects of tannins on population dynamics of sympatric seed-eating rodents: the potential role of gut tannin-degrading bacteria

Oecologia ◽  
2018 ◽  
Vol 187 (3) ◽  
pp. 667-678 ◽  
Author(s):  
Yihao Zhang ◽  
Andrew W. Bartlow ◽  
Zhenyu Wang ◽  
Xianfeng Yi
Keyword(s):  
Population Dynamics ◽  
Potential Role ◽  
Degrading Bacteria ◽  
Seed Eating

scholarly journals Malaria and red cell genetic defects

Blood ◽  
1989 ◽  
Vol 74 (4) ◽  
pp. 1213-1221 ◽  
Author(s):  
RL Nagel ◽  
EF Jr Roth
Keyword(s):  
Culture System ◽  
Potential Role ◽  
Dna Analysis ◽  
Red Cell ◽  
Metabolic Products ◽  
Recombinant Technology ◽  
Host Parasite ◽  
Made In

Abstract The study of inherited RBC resistance to malaria has increased our knowledge of the biochemistry and physiology of the host-parasite interaction and suggested potential sites for therapeutic intervention. Discovery by Jensen and Trager of the in vitro culture system for P falciparum has facilitated research in this area. Known RBC defects may affect invasion, growth, or merozoite liberation (Fig 1). Significant advances made in understanding mechanisms underlying protection against malaria should not obscure the fact that the data are far from complete. More knowledge is needed about the influence of the erythrocyte cytoskeleton on invasion and growth of parasites as well as the potential role of phospholipids, erythrocyte enzymes other than G6PD, or other metabolic products. Application of DNA analysis and recombinant technology may have an increasing impact on study of the interaction of RBC defects with malarial parasites.

Behavioral stabilization of host-parasite population dynamics

1992 ◽  
Vol 42 (3) ◽  
pp. 308-320 ◽  
Author(s):  
Marc Mangel ◽  
Bernard D. Roitberg
Keyword(s):  
Population Dynamics ◽  
Parasite Population ◽  
Host Parasite

Do parasites matter? Assessing the fitness consequences of haemogregarine infection in snakes

2006 ◽  
Vol 84 (5) ◽  
pp. 668-676 ◽  
Author(s):  
G.P. Brown ◽  
C.M. Shilton ◽  
R. Shine
Keyword(s):  
Evolutionary Ecology ◽  
Natural Populations ◽  
Blood Parasites ◽  
Antipredator Behaviour ◽  
Host Fitness ◽  
Host Parasite Interactions ◽  
Fitness Consequences ◽  
Tropical Australia ◽  
Host Parasite ◽  
Striking Contrast

Although much research in evolutionary ecology is based upon the premise that high levels of parasitism impair the host's functioning, the assumed link between parasitism and fitness has been assessed for relatively few kinds of animals. At our study site in tropical Australia, keelback snakes ( Tropidonophis mairii (Gray, 1841), Colubridae) are heavily infected with haemogregarine blood parasites: 90% of snakes that we tested carried the parasite, with the proportion of erythrocytes containing haemogregarines averaging 15% and ranging up to a remarkable 64%. Prevalence increased with snake body size, but intensity decreased with age. Unlike lizards studied previously, the snakes did not respond to haemogregarine infection by releasing immature erythrocytes into the circulation. In striking contrast to results from a recent study on a sympatric snake species, we did not find any empirical links between parasite numbers and several measures of host fitness (body condition, growth rate, feeding rate, antipredator behaviour, locomotor performance, reproductive status, reproductive output, and recapture rate). The association between this parasite and its host thus appears to be surprisingly benign, suggesting that host–parasite interactions sometimes may have only trivial consequences for host fitness in natural populations. Plausibly, host–parasite coevolution weakens or eliminates fitness costs of parasitism.

The Application of Ecological Principles to Orchard Entomology in Canada

1964 ◽  
Vol 96 (1-2) ◽  
pp. 348-356 ◽  
Author(s):  
E. J. LeRoux
Keyword(s):  
Population Dynamics ◽  
Precise Measurement ◽  
Natural Populations ◽  
Future Research ◽  
Pest Species ◽  
Apple Orchards ◽  
Mortality Factors ◽  
Ecological Principles ◽  
Insight Into

AbstractA knowledge of ecological principles is essential to the successful development of future research on pest control problems in Canadian orchard entomology. Such knowledge should be especially helpful in spotlighting omissions in past studies as well as indicating new areas of study in the future. In particular, the ecosystem concept should serve not only as a basis for evaluating and bringing together existing data but also as a guide in the collection, integration and interpretation of new data.Our approach should be to study the population dynamics of major arthropod pests in Canadian apple orchards to obtain data of the fundamental kind on natural populations of these species. Since this approach is dependent on precise measurement of the population and its mortality factors, as well as on the mathematical modelling of the data obtained, unambiguous deduction and greater understanding and utilization of the results would then be possible.Examples from a recent eight-year study of the population dynamics of two pest species in Canadian apple orchards reveal that the fundamental approach to pest problems in Canada is both feasible and practical, and that the results can yield considerable insight into the role of mortality factors in population regulation as well as in control of pest stages of economic importance.

scholarly journals Sex ratio variation shapes the ecological effects of a globally introduced freshwater fish

2015 ◽  
Vol 282 (1817) ◽  
pp. 20151970 ◽  
Author(s):  
David C. Fryxell ◽  
Heather A. Arnett ◽  
Travis M. Apgar ◽  
Michael T. Kinnison ◽  
Eric P. Palkovacs
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Evolutionary Ecology ◽  
Natural Populations ◽  
Trophic Cascades ◽  
Zooplankton Abundance ◽  
Sexually Dimorphic ◽  
Ecosystem Responses ◽  
Ratio Variation

Sex ratio and sexual dimorphism have long been of interest in population and evolutionary ecology, but consequences for communities and ecosystems remain untested. Sex ratio could influence ecological conditions whenever sexual dimorphism is associated with ecological dimorphism in species with strong ecological interactions. We tested for ecological implications of sex ratio variation in the sexually dimorphic western mosquitofish, Gambusia affinis . This species causes strong pelagic trophic cascades and exhibits substantial variation in adult sex ratios. We found that female-biased populations induced stronger pelagic trophic cascades compared with male-biased populations, causing larger changes to key community and ecosystem responses, including zooplankton abundance, phytoplankton abundance, productivity, pH and temperature. The magnitude of such effects indicates that sex ratio is important for mediating the ecological role of mosquitofish. Because both sex ratio variation and sexual dimorphism are common features of natural populations, our findings should encourage broader consideration of the ecological significance of sex ratio variation in nature, including the relative contributions of various sexually dimorphic traits to these effects.

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