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.

scholarly journals Host-pathogen coevolution increases genetic variation in susceptibility to infection

2018 ◽  
Author(s):  
Elizabeth ML Duxbury ◽  
Jonathan P Day ◽  
Davide Maria Vespasiani ◽  
Yannik Thüringer ◽  
Ignacio Tolosana ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Genetic Variants ◽  
Genetic Architecture ◽  
Natural Populations ◽  
Major Effect ◽  
Cross Infection ◽  
Host Susceptibility ◽  
Susceptibility To Infection ◽  
Host Parasite Interactions ◽  
Host Parasite

AbstractIt is common to find considerable genetic variation in susceptibility to infection in natural populations. We have investigated whether natural selection increases this variation by testing whether host populations show more genetic variation in susceptibility to pathogens that they naturally encounter than novel pathogens. In a large cross-infection experiment involving four species of Drosophila and four host-specific viruses, we always found greater genetic variation in susceptibility to viruses that had coevolved with their host. We went on to examine the genetic architecture of resistance in one host species, finding that there are more major-effect genetic variants in coevolved host-parasite interactions. We conclude that selection by pathogens increases genetic variation in host susceptibility, and much of this effect is caused by the occurrence of major-effect resistance polymorphisms within populations.

scholarly journals Genetic colour polymorphism is associated with avian malarial infections

2016 ◽  
Vol 12 (12) ◽  
pp. 20160839 ◽  
Author(s):  
Laura Gangoso ◽  
Rafael Gutiérrez-López ◽  
Josué Martínez-de la Puente ◽  
Jordi Figuerola
Keyword(s):  
Genetic Diversity ◽  
Immune Responses ◽  
Genetic Basis ◽  
Pleiotropic Effects ◽  
Colour Polymorphism ◽  
Blood Parasites ◽  
Immune Functions ◽  
Host Parasite Interactions ◽  
Differential Ability ◽  
Host Parasite

Individual genetic diversity is predicted to influence host–parasite interactions. Together with the genes directly associated with immune responses, variation in genes regulating vertebrate melanin-based pigmentation may play an important role in these interactions, mainly through the pleiotropic effects that affect colour-specific physiology, behaviour and immunity. Here, we test the hypothesis that the prevalence of avian malarial parasites differs between phenotypes in a raptor species in which the genetic basis of colour polymorphism and its pleiotropic effects over immune functions are known. We found that dark morphs had a higher prevalence of Plasmodium parasites than pale ones but detected no such association for Haemoproteus . This pattern may be associated with unequal exposure to vectors or, as suggested by our circumstantial evidence, to a differential ability to mount an immune response against blood parasites.

scholarly journals Immune defence, parasite evasion strategies and their relevance for ‘macroscopic phenomena’ such as virulence

2008 ◽  
Vol 364 (1513) ◽  
pp. 85-98 ◽  
Author(s):  
Paul Schmid-Hempel
Keyword(s):  
Immune Evasion ◽  
Life History Theory ◽  
Evolutionary Ecology ◽  
Parasite Clearance ◽  
Multiple Infections ◽  
Parasite Fitness ◽  
Host Parasite Interactions ◽  
Evolution Of Virulence ◽  
Host Parasite ◽  
Insight Into

The discussion of host–parasite interactions, and of parasite virulence more specifically, has so far, with a few exceptions, not focused much attention on the accumulating evidence that immune evasion by parasites is not only almost universal but also often linked to pathogenesis, i.e. the appearance of virulence. Now, the immune evasion hypothesis offers a deeper insight into the evolution of virulence than previous hypotheses. Sensitivity analysis for parasite fitness and life-history theory shows promise to generate a more general evolutionary theory of virulence by including a major element, immune evasion to prevent parasite clearance from the host. Also, the study of dose–response relationships and multiple infections should be particularly illuminating to understand the evolution of virulence. Taking into account immune evasion brings immunological processes to the core of understanding the evolution of parasite virulence and for a range of related issues such as dose, host specificity or immunopathology. The aim of this review is to highlight the mechanism underlying immune evasion and to discuss possible consequences for the evolutionary ecology analysis of host–parasite interactions.

The role of the environment in the evolutionary ecology of host parasite interactions

2008 ◽  
Vol 8 (3) ◽  
pp. 302-305 ◽  
Author(s):  
Pedro F. Vale ◽  
Lucie Salvaudon ◽  
Oliver Kaltz ◽  
Simon Fellous
Keyword(s):  
Evolutionary Ecology ◽  
Host Parasite Interactions ◽  
Host Parasite

scholarly journals Genomic evidence for population-specific responses to coevolving parasites in a New Zealand freshwater snail

2016 ◽  
Author(s):  
Laura Bankers ◽  
Peter Fields ◽  
Kyle E. McElroy ◽  
Jeffrey L. Boore ◽  
John M. Logsdon ◽  
...  
Keyword(s):  
Natural Populations ◽  
Primary Source ◽  
Population Level ◽  
Freshwater Snail ◽  
Sequence Evolution ◽  
Specific Host ◽  
Host Parasite Interactions ◽  
Evolutionary Trajectories ◽  
Host Parasite ◽  
Genomic Basis

AbstractReciprocal coevolving interactions between hosts and parasites are a primary source of strong selection that can promote rapid and often population- or genotype-specific evolutionary change. These host-parasite interactions are also a major source of disease. Despite their importance, very little is known about the genomic basis of coevolving host-parasite interactions in natural populations, especially in animals. Here, we use gene expression and sequence evolution approaches to take critical steps towards characterizing the genomic basis of interactions between the freshwater snail Potamopyrgus antipodarum and its coevolving sterilizing trematode parasite, Microphallus sp., a textbook example of natural coevolution. We found that Microphallus-infected P. antipodarum exhibit systematic downregulation of genes relative to uninfected P. antipodarum. The specific genes involved in parasite response differ markedly across lakes, consistent with a scenario where population-level coevolution is leading to population-specific host-parasite interactions and evolutionary trajectories. We also used an FST-based approach to identify a set of loci that represent promising candidates for targets of parasite-mediated selection across lakes as well as within each lake population. These results constitute the first genomic evidence for population-specific responses to coevolving infection in the P. antipodarum-Microphallus interaction and provide new insights into the genomic basis of coevolutionary interactions in nature.

scholarly journals Description and Molecular Characterization of Two Species of Avian Blood Parasites, with Remarks on Circadian Rhythms of Avian Haematozoa Infections

Animals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3490
Author(s):  
Carolina Romeiro Fernandes Chagas ◽  
Rasa Binkienė ◽  
Gediminas Valkiūnas
Keyword(s):  
Circadian Rhythms ◽  
Disease Transmission ◽  
Blood Parasites ◽  
Avian Host ◽  
Blood Samples ◽  
Host Parasite Interactions ◽  
Avian Blood ◽  
Avian Blood Parasites ◽  
Host Parasite

Avian blood parasites are remarkably diverse and frequently occur in co-infections, which predominate in wildlife. This makes wildlife pathogen research challenging, particularly if they belong to closely related groups, resulting in diagnostic problems and poor knowledge about such infections as well as the patterns of their co-occurrence and interactions. This is particularly true due to the periodicity (circadian rhythms) of parasitemia, which means that different parasitemia and parasite stages might be found throughout the day. We analysed blood samples from a Eurasian blackbird (Turdus merula) and a Song thrush (Turdus philomelos). This study aimed to describe a new avian Lankesterella species and molecularly characterize and redescribe Splendidofilaria mavis, a common avian filarioid nematode. Additionally, it was possible to investigate the circadian rhythms of the avian blood parasites belonging to Plasmodium, Haemoproteus, Leucocytozoon, and Trypanosoma, which occurred in co-infection in the same avian host individuals. Different circadian rhythms were seen in different parasites, with Plasmodium sp. peaks occurring at midday, Leucocytozoon spp. peaks mainly during the evening and night, and Trypanosoma spp. and microfilariae peaks at midnight. No periodicity was seen in Haemoproteus and Lankesterella species infections. The time of parasitemia peaks most likely coincides with the time of vectors’ activity, and this should be beneficial for transmission. Knowledge about the circadian rhythms is needed for better understanding patterns in host-parasite interactions and disease transmission.

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).

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