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David C. Heins - One of the best experts on this subject based on the ideXlab platform.
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are solo infections of the diphyllobothriidean cestode Schistocephalus solidus more virulent than multiple infections
Parasitology, 2019Co-Authors: David C. Heins, Kristine N Moody, Sophia MillerAbstract:We performed a long-term natural experiment investigating the impact of the diphyllobotriidean cestode Schistocephalus solidus on the body condition and clutch size (CS) of threespine stickleback Gasterosteus aculeatus, its second intermediate host, and the growth of larval parasites in host fish. We tested the hypothesis that single S. solidus infections were more virulent than multiple infections. We also asked whether the metrics of mean and total parasite mass (proxies for individual and total volume, respectively) were consistent with predictions of the resource constraints or the life history strategy (LHS) hypothesis for the growth of, hence exploitation by, larval helminths in intermediate hosts. The samples were drawn from Walby Lake, Alaska in eight of 11 years. Host body condition and CS (egg number per spawning bout) decreased significantly with intensity after adjustments for host size and parasite index. Thus, infections have an increasingly negative impact on measures of host fitness with greater intensity, in contrast to the hypothesis that single infections are more harmful than multiple infections. We also found that mean parasite mass decreased with intensity while total parasite mass increased with intensity as predicted by the LHS hypothesis.
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the cestode parasite Schistocephalus pungitii castrator or nutrient thief of ninespine stickleback fish
Parasitology, 2017Co-Authors: David C. HeinsAbstract:In this investigation, the host-parasite relationship of ninespine stickleback fish Pungitius pungitius and the cestode parasite Schistocephalus pungitii was studied using samples from Dog Bone Lake, Kenai Peninsula, Alaska, to test the hypothesis that S. pungitii is a castrator of ninespine stickleback. Infected, adult females of all sizes (ages) were capable of producing clutches of eggs. S. pungitii had a negative effect on the ability of host females to produce a clutch, which was related to increasing parasite:host mass ratio (parasite index, PI). Among infected females with egg clutches, both clutch size and egg size were reduced; and the reduction increased with greater PI. The results of this study are consistent with the hypothesis that S. pungitii causes host sterility as a result of simple nutrient theft and is not a true castrator as hypothesized in earlier reports. The degree of parasite-induced sterility appears to vary among populations of the ninespine stickleback, perhaps reflecting differences in resource availability. Populations of ninespine stickleback appear to show a greater reduction in host reproductive capacity with PI than populations of the threespine stickleback infected by Schistocephalus solidus, possibly owing, in part, to the length-adjusted somatic mass of the threespine stickleback being greater.
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Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus solidus in Alaska.
The Journal of parasitology, 2015Co-Authors: David C. Heins, D. M. Eidam, John A. BakerAbstract:Abstract This study provides direct evidence for the timing of infections by Schistocephalus solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May–June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections.
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Landscape Genetics of Schistocephalus solidus Parasites in Threespine Stickleback (Gasterosteus aculeatus) from Alaska
PloS one, 2015Co-Authors: C. Grace Sprehn, Michael J. Blum, Thomas P. Quinn, David C. HeinsAbstract:The nature of gene flow in parasites with complex life cycles is poorly understood, particularly when intermediate and definitive hosts have contrasting movement potential. We examined whether the fine-scale population genetic structure of the diphyllobothriidean cestode Schistocephalus solidus reflects the habits of intermediate threespine stickleback hosts or those of its definitive hosts, semi-aquatic piscivorous birds, to better understand complex host-parasite interactions. Seventeen lakes in the Cook Inlet region of south-central Alaska were sampled, including ten in the Matanuska-Susitna Valley, five on the Kenai Peninsula, and two in the Bristol Bay drainage. We analyzed sequence variation across a 759 bp region of the mitochondrial DNA (mtDNA) cytochrome oxidase I region for 1,026 S. solidus individuals sampled from 2009-2012. We also analyzed allelic variation at 8 microsatellite loci for 1,243 individuals. Analysis of mtDNA haplotype and microsatellite genotype variation recovered evidence of significant population genetic structure within S. solidus. Host, location, and year were factors in structuring observed genetic variation. Pairwise measures revealed significant differentiation among lakes, including a pattern of isolation-by-distance. Bayesian analysis identified three distinct genotypic clusters in the study region, little admixture within hosts and lakes, and a shift in genotype frequencies over time. Evidence of fine-scale population structure in S. solidus indicates that movement of its vagile, definitive avian hosts has less influence on gene flow than expected based solely on movement potential. Observed patterns of genetic variation may reflect genetic drift, behaviors of definitive hosts that constrain dispersal, life history of intermediate hosts, and adaptive specificity of S. solidus to intermediate host genotype.
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fecundity compensation and fecundity reduction among populations of the three spined stickleback infected by Schistocephalus solidus in alaska
Parasitology, 2014Co-Authors: David C. Heins, John A. BakerAbstract:We surveyed nine populations of the three-spined stickleback infected by the diphyllobothriidean cestode Schistocephalus solidus from south-central Alaska for two apparent forms of tolerance to infection in females capable of producing egg clutches notwithstanding large parasite burdens. Seven populations exhibited fecundity reduction, whereas two populations showed fecundity compensation. Our data suggest that fecundity reduction, a side effect resulting from nutrient theft, occurs in two phases of host response influenced by the parasite : host body mass (BM) ratio. The first is significantly reduced ovum mass without significant reduction in clutch size, and the second one involves significant reductions in both ovum mass and clutch size. Thus, ovum mass of host females who are functionally being starved through nutrient theft seems to be more readily influenced by parasitism and, therefore, decreased before clutch size is reduced. This inference is consistent with expectations based on the biology of and effect of feeding ration on reproduction in stickleback females. Fecundity compensation appears to be uncommon among populations of three-spined stickleback in Alaska and rare among populations throughout the northern hemisphere. Fecundity reduction seems to be common, at least among stickleback populations in Alaska.
Iain Barber - One of the best experts on this subject based on the ideXlab platform.
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transcriptome sequences spanning key developmental states as a resource for the study of the cestode Schistocephalus solidus a threespine stickleback parasite
GigaScience, 2016Co-Authors: Francois Olivier Hebert, Iain Barber, Stephan Grambauer, Christian R Landry, Nadia AubinhorthAbstract:Background Schistocephalus solidus is a well-established model organism for studying the complex life cycle of cestodes and the mechanisms underlying host-parasite interactions. However, very few large-scale genetic resources for this species are available. We have sequenced and de novo-assembled the transcriptome of S. solidus using tissues from whole worms at three key developmental states - non-infective plerocercoid, infective plerocercoid and adult plerocercoid - to provide a resource for studying the evolution of complex life cycles and, more specifically, how parasites modulate their interactions with their hosts during development.
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The Effect of Salinity on Egg Development and Viability of Schistocephalus solidus (Cestoda: Diphyllobothriidea)
The Journal of parasitology, 2015Co-Authors: Natalie E. Simmonds, Iain BarberAbstract:Schistocephalus solidus plerocercoids commonly infect three-spined stickleback Gasterosteus aculeatus populations in brackish and freshwaters, but infections are typically absent from marine populations. Here we provide an experimental test of the salinity tolerance of S. solidus eggs, to determine the role of salinity in limiting the distribution of infection in coastal zones. We find that S. solidus eggs, derived from the in vitro culture of 3 different plerocercoids, developed normally in salinities of up to 12.5‰, but above this egg viability dropped rapidly, and no egg hatching was observed at salinities above 20‰. Our results are consistent with the distribution of infections in natural stickleback populations and add resolution to previous descriptive observations on salinity tolerance in S. solidus. They also demonstrate that S. solidus presents a novel disease challenge to marine populations of three-spined sticklebacks entering brackish and freshwater environments.
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distinct lineages of Schistocephalus parasites in threespine and ninespine stickleback hosts revealed by dna sequence analysis
PLOS ONE, 2011Co-Authors: Nicole Nishimura, Iain Barber, David C. Heins, Ryan O Andersen, William A CreskoAbstract:Parasitic interactions are often part of complex networks of interspecific relationships that have evolved in biological communities. Despite many years of work on the evolution of parasitism, the likelihood that sister taxa of parasites can co-evolve with their hosts to specifically infect two related lineages, even when those hosts occur sympatrically, is still unclear. Furthermore, when these specific interactions occur, the molecular and physiological basis of this specificity is still largely unknown. The presence of these specific parasitic relationships can now be tested using molecular markers such as DNA sequence variation. Here we test for specific parasitic relationships in an emerging host-parasite model, the stickleback-Schistocephalus system. Threespine and ninespine stickleback fish are intermediate hosts for Schistocephalus cestode parasites that are phenotypically very similar and have nearly identical life cycles through plankton, stickleback, and avian hosts. We analyzed over 2000 base pairs of COX1 and NADH1 mitochondrial DNA sequences in 48 Schistocephalus individuals collected from threespine and ninespine stickleback hosts from disparate geographic regions distributed across the Northern Hemisphere. Our data strongly support the presence of two distinct clades of Schistocephalus, each of which exclusively infects either threespine or ninespine stickleback. These clades most likely represent different species that diverged soon after the speciation of their stickleback hosts. In addition, genetic structuring exists among Schistocephalus taken from threespine stickleback hosts from Alaska, Oregon and Wales, although it is much less than the divergence between hosts. Our findings emphasize that biological communities may be even more complex than they first appear, and beg the question of what are the ecological, physiological, and genetic factors that maintain the specificity of the Schistocephalus parasites and their stickleback hosts.
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Variation in the reproductive potential of Schistocephalus infected male sticklebacks is associated with 11-ketotestosterone titre
Hormones and Behavior, 2011Co-Authors: Vicki Macnab, Alexander P. Scott, Ioanna Katsiadaki, Iain BarberAbstract:Abstract Parasites can impact host reproduction by interfering with host endocrine systems, but the adaptive nature of such effects is disputed. Schistocephalus solidus plerocercoids are parasites of three-spined sticklebacks Gasterosteus aculeatus that are often associated with impaired host reproduction. Here, we relate reproductive behavior and physiology to levels of the androgen 11-ketotestosterone (11KT) in naturally infected and non-infected male sticklebacks from two UK populations. In one population infected males harbored heavy infections and showed uniformly reduced 11KT titres and kidney spiggin (nesting glue protein) content compared to non-infected fish. However in a second population infection levels were more variable and males with smaller infections recorded 11KT and spiggin titres that overlapped those of non-infected fish; among infected males from this population 11KT and kidney spiggin also both correlated negatively with infection severity. Male reproductive behavior correlated closely with 11KT titre in both populations, and infected males with high 11KT levels exhibited normal reproductive behavior. Our results suggest that Schistocephalus infection per se does not block reproductive development in male sticklebacks, and that some male fish may have the ability to breed whilst infected. Our results are not consistent with the hypothesis that Schistocephalus adaptively castrates male hosts via endocrine disruption; rather they support the hypothesis that reproductive disruption is a side effect of the energetic costs of infection.
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the three spined stickleback Schistocephalus solidus system an experimental model for investigating host parasite interactions in fish
Parasitology, 2010Co-Authors: Iain Barber, Jorn P ScharsackAbstract:Plerocercoids of the pseudophyllidean cestode Schistocephalus solidus infect the three-spined stickleback Gasterosteus aculeatus, with important consequences for the biology of host fish. Techniques for culturing the parasite in vitro and generating infective stages that can be used to infect sticklebacks experimentally have been developed, and the system is increasingly used as a laboratory model for investigating aspects of host-parasite interactions. Recent experimental laboratory studies have focused on the immune responses of hosts to infection, the consequences of infection for the growth and reproductive development of host fish and the effects of infection on host behaviour. Here we introduce the host and the parasite, review the major findings of these recent experimental infection studies and identify further aspects of host parasite interactions that might be investigated using the system.
John A. Baker - One of the best experts on this subject based on the ideXlab platform.
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Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus solidus in Alaska.
The Journal of parasitology, 2015Co-Authors: David C. Heins, D. M. Eidam, John A. BakerAbstract:Abstract This study provides direct evidence for the timing of infections by Schistocephalus solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May–June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections.
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fecundity compensation and fecundity reduction among populations of the three spined stickleback infected by Schistocephalus solidus in alaska
Parasitology, 2014Co-Authors: David C. Heins, John A. BakerAbstract:We surveyed nine populations of the three-spined stickleback infected by the diphyllobothriidean cestode Schistocephalus solidus from south-central Alaska for two apparent forms of tolerance to infection in females capable of producing egg clutches notwithstanding large parasite burdens. Seven populations exhibited fecundity reduction, whereas two populations showed fecundity compensation. Our data suggest that fecundity reduction, a side effect resulting from nutrient theft, occurs in two phases of host response influenced by the parasite : host body mass (BM) ratio. The first is significantly reduced ovum mass without significant reduction in clutch size, and the second one involves significant reductions in both ovum mass and clutch size. Thus, ovum mass of host females who are functionally being starved through nutrient theft seems to be more readily influenced by parasitism and, therefore, decreased before clutch size is reduced. This inference is consistent with expectations based on the biology of and effect of feeding ration on reproduction in stickleback females. Fecundity compensation appears to be uncommon among populations of three-spined stickleback in Alaska and rare among populations throughout the northern hemisphere. Fecundity reduction seems to be common, at least among stickleback populations in Alaska.
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DO HEAVY BURDENS OF Schistocephalus SOLIDUS IN JUVENILE THREESPINE STICKLEBACK RESULT IN DISASTER FOR THE PARASITE
The Journal of parasitology, 2011Co-Authors: David C. Heins, John A. BakerAbstract:The diphyllobothriidean cestode Schistocephalus solidus typically infects threespine sticklebacks that are too small to allow the parasite to reach a mature size. As a result, the parasite must allow further growth of its host to reach the size at which it becomes competent to infect and reproduce in the definitive host. At times, however, intensity of infection can be high, leading to crowding among parasites and to heavy burdens causing mortality among hosts. Our data show that, during a previously observed epizootic, large percentages of plerocercoids (average 75% per host, 82% among all parasites pooled) did not grow to become massive enough in 1-yr-old threespine sticklebacks to be capable of establishment and maturation in the definitive host. Massive deaths of 1-yr-old sticklebacks due to infection during the epizootic resulted in the great misfortune of a disaster for a large number of parasites, resulting in dramatically reduced transmission of S. solidus.
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Processes Influencing the Duration and Decline of Epizootics in Schistocephalus solidus
The Journal of parasitology, 2011Co-Authors: David C. Heins, John A. Baker, Dillon M. GreenAbstract:Abstract The interplay of intermediate host fish and plerocercoids of diphyllobothriidean cestodes results in epizootics that are deceptively simple, but conceal complex biotic and abiotic interactions shaping each event independently. Although general descriptions of epizootics and some details of biotic interactions between enemies are known, much remains to be discovered about the abiotic and biotic forces and their interactions driving epizootics. This study shows that the duration of an epizootic of Schistocephalus solidus was sustained by high prevalence, mean intensity, and PI (parasite index—parasite∶host biomass ratio) levels among young-of-the-year and 1-yr-old threespine sticklebacks. Many infections and most parasite growth in young-of-the-year fish apparently occurred under the ice during the winter. Few new infections appear to have occurred among 1-yr-old fish, which may live 2 yr and sometimes 3 yr. The decline of the epizootic occurred as the recruitment of 1 to 2-yr-old hosts decreased s...
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evolutionary significance of fecundity reduction in threespine stickleback infected by the diphyllobothriidean cestode Schistocephalus solidus
Biological Journal of The Linnean Society, 2010Co-Authors: David C. Heins, John A. Baker, Melissa A Toups, Emily L BirdenAbstract:Parasites may cause fecundity reduction in their hosts via life-history strategies involving simple nutrient theft or manipulation of host energy allocation. Simple theft of nutrients incidentally reduces host energy allocation to reproduction, whereas manipulation is a parasite-driven diversion of energy away from host reproduction. We aimed to determine whether the diphyllobothriidean cestode parasite Schistocephalus solidus causes loss of fecundity in the threespine stickleback fish (Gasterosteus aculeatus) through simple nutrient theft or the manipulation of host energy allocation. In one stickleback population (Walby Lake, Matanuska-Susitna Valley, Alaska), there was no difference in the sizes and ages of infected and uninfected reproducing females. Lightly- and heavily-infected females produced clutches of eggs, but increasingly smaller percentages of infected females produced clutches as the parasite-to-host biomass ratio (PI) increased. Infected, clutch-bearing sticklebacks showed reductions in clutch size, egg mass, and clutch mass, which were related to increases in PI and reflected a reduction in reproductive parameters as growth in parasite mass occurs. The findings obtained for this population are consistent with the hypothesis of simple nutrient theft; however, populations of S. solidus in other regions may manipulate host energy allocation. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 835–846.
Manfred Milinski - One of the best experts on this subject based on the ideXlab platform.
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Schistocephalus cotti n sp cestoda pseudophyllidea plerocercoids from bullheads cottus gobio l in an arctic river in finland with a key to the plerocercoids of the palaearctic species of the genus
Systematic Parasitology, 2006Co-Authors: James C Chubb, T Seppala, A Luscher, Manfred Milinski, E T ValtonenAbstract:We compared plerocercoids of Schistocephalus Creplin, 1829 from Cottus gobio (n = 57) and Gasterosteus aculeatus f. semiarmatus (n = 45) from the River Utsjoki, Finland, taken only from single worm infections. Segment numbers in the two populations were distinct (G. aculeatus range 55–107, average 74 (SE 1.66), median 73; C. gobio range 122–189, average 146 (SE 1.78); median 144). The mean difference between populations, 71.47, t = 28.76 with 100 degrees of freedom, two-tailed p value <0.001, was considered extremely significant. Amplification of microsatellite loci that were originally designed for Schistocephalus from G. aculeatus was positive for all larvae from G.␣aculeatus (n = 20), whereas in no plerocercoids from C. gobio (n = 20) were any of the six microsatellites amplified, indicating that plerocercoids from G. aculeatus and C. gobio were two distinct genetic populations of Schistocephalus. The material from C. gobio is described as S. cotti n. sp. Plerocercoids of the Palaearctic species of Schistocephalus are identified as follows: S. nemachili Dubinina, 1959 with 228–235 or more segments, specific to Barbatula spp. (Balitoridae); S. pungitii Dubinina, 1959 with 62–92 (usually 70–80) segments, specific to Pungitius pungitius; S. solidus (Muller, 1776) in two forms, one in G. aculeatus f. leiurus and f.␣semiarmatus, with 48–100 (usually 65–75) segments, and the other in G. aculeatus f. trachurus, with 99–138 (usually 112–122) segments; and S. cotti n. sp. with 103–189 (usually 130–159) segments, probably specific to cottids. Nearctic Schistocephalus were not considered owing to the uncertain status of some North American records. Some other species of Schistocephalus of highly doubtful status were briefly noted. Cross-infection experiments and molecular studies are recommended to further elucidate the interrelationships between the various species of Schistocephalus.
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host parasite interactions in a cestode with a complex life cycle Schistocephalus solidus
2006Co-Authors: Katrin Hammerschmidt, Manfred Milinski, M SpindlerAbstract:Many parasites have complex life cycles, i.e. they have to pass through several host species to reach maturity. Hence complex life cycles often consist of invertebrate and vertebrate hosts, the parasite likely varies in the machinery required for infection, exploitation and transmission of each host. Does the ability to optimally exploit one host inevitably lead to a reduced ability for the parasite to exploit another host in its life cycle? To answer this question, I analysed parasite life history traits like transmission, infection, and establishment in the model system of the tapeworm Schistocephalus solidus in relation to its two intermediate hosts, a cyclopoid copepod, and the three-spined stickleback. In this thesis, I particularly focus on interactions with the hosts' immune systems and on constraints, which are potentially shaping the evolution of virulence in parasites with complex life cycles.
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hosts and parasites many ways of interactions an approach with two model organisms the three spined stickleback gasterosteus aculeatus and its cestode parasite Schistocephalus solidus
2006Co-Authors: Ilonka Jager, Manfred Milinski, Heinz BrendelbergerAbstract:Parasites are considered to be one of the major driving forces in the evolution of organisms. The outcome of an infection might, however, not only be determined by host-parasite interactions but also by within-host dynamics. Using the three-spined stickleback (Gasterosteus aculeatus) and the tapeworm Schistocephalus solidus as model organisms, this thesis addresses various aspects of such interactions. Apart from parasite mate choice as potentially important parasite-parasite interaction, dynamics of multiple infections and various aspects of the host's immune system were investigated.
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Fitness consequences of selfing and outcrossing in the cestode Schistocephalus solidus
Integrative and comparative biology, 2006Co-Authors: Manfred MilinskiAbstract:Synopsis Mixed-mating, that is reproduction by both self-fertilization and cross-fertilization is common in hermaphroditic parasites. Its maintenance poses, however, a problem for evolutionary biology. The tapeworm Schistocephalus solidus Muller 1776, served as a model to study experimentally the consequences of selfing and outcrossing in its 2 consecutive intermediate hosts, a copepod (Macrocyclops albidus Jurine) and the three-spined stickleback fish (Gasterosteus aculeatus). Size-matched tapeworms were allowed to reproduce either alone or in pairs in an in vitro system that replaced the definitive bird host's gut. Selfed eggs from singletons had a 4 times lower hatching success than outcrossed eggs from pairs. Outcrossed offspring achieved both a higher infection success and a higher weight in the copepod, and a higher number of parasites per host in both intermediate hosts, but only under competition. Outcrossed offspring were generally more successful. If a S. solidus plerocercoid has a partner in the bird's gut, they should outcross unless they differ in size and thus cannot solve the Hermaphrodite's Dilemma cooperatively. Using microsatellite markers, the proportion of selfed offspring and the total reproductive output of each worm within pairs varying in mean weight and in weight difference was measured. Worms produced more selfed offspring not only with increasing weight difference as expected but also with decreasing total weight of the pair. If small worms were selfed, they have already purged deleterious mutations and would thus be better selfers in a year with low parasite density when worms cannot find partners. To maintain this advantage they should self a higher proportion of their eggs even with a partner. Here I review recent exprimental evidence.
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simultaneous hermaphrodites reproducing in pairs self fertilize some of their eggs an experimental test of predictions of mixed mating and hermaphrodite s dilemma theory
Journal of Evolutionary Biology, 2003Co-Authors: A Luscher, Manfred MilinskiAbstract:Theory predicts (1) that mixed-mating systems (i.e. reproduction through both selfing and outcrossing) should usually not evolve and (2) that reproducing simultaneous hermaphrodites should be in a conflict over the preferred sexual role (The Hermaphrodite's Dilemma). In an in vitro system with the endoparasitic cestode Schistocephalus solidus, a simultaneous hermaphrodite, we tested predictions of both the mixed-mating and the Hermaphrodite's Dilemma theory. Using microsatellite markers, we measured the proportion of selfed offspring and the total reproductive output of each worm within pairs varying in mean weight and weight difference. Worms produced more outbred offspring not only with increasing total weight of the pair, but also with decreasing weight difference between the two paired worms. These results suggest: (1) that this parasite species reproduces by mixed-mating, which may be maintained by stochastic density fluctuations in the definitive host and hence unpredictability of self reproduction and (2) reproductive conflict may prevent worm pairs from achieving an optimal intermediate selfing rate.
Nadia Aubinhorth - One of the best experts on this subject based on the ideXlab platform.
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an edna qpcr assay to detect the presence of the parasite Schistocephalus solidus inside its threespine stickleback host
The Journal of Experimental Biology, 2018Co-Authors: Chloé Suzanne Berger, Nadia AubinhorthAbstract:Detecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. The Schistocephalus solidus-threespine stickleback pair has been studied extensively to investigate host phenotypic alterations associated with a parasite with a complex life cycle. This cestode is localized inside the stickleback's abdominal cavity and can be visually detected only once it passes a mass threshold. We present a non-lethal quantitative PCR (qPCR) approach based on detection of environmental DNA from the worm (eDNA), sampled in the fish abdominal cavity. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. solidus infection status. There was a significant correlation between eDNA concentration and total parasitic mass. We also assessed ventilation rate as a complementary mean to detect infection. Our eDNA detection method gives a reliable presence/absence response and its future use for quantitative assessment of infection is promising.
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a edna qpcr assay to non invasively detect the presence of the parasite Schistocephalus solidus inside its threespine stickleback host
bioRxiv, 2018Co-Authors: Chloé Suzanne Berger, Nadia AubinhorthAbstract:Detecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. The Schistocephalus solidus - threespine stickleback pair has been studied extensively to investigate host phenotypic alterations associated with a parasite with a complex life cycle. This cestode is localized inside the stickleback9s abdominal cavity and can be visually detected only once it passes a mass threshold. We present a non-invasive quantitative PCR approach based on detection of environmental DNA from the worm (eDNA), sampled in the fish abdominal cavity. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. solidus infection status. There was a significant correlation between eDNA concentration and total parasitic mass. We also assessed ventilation rates as a complimentary mean to detect infection. Our eDNA detection method gives a reliable presence/absence response and its future use for quantitative assessment is promising.
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testing the parasite mass burden effect on alteration of host behaviour in the Schistocephalus stickleback system
The Journal of Experimental Biology, 2018Co-Authors: Lucie Grecias, Julie Valentin, Nadia AubinhorthAbstract:ABSTRACT Many parasites with complex life cycles modify the behaviour of their intermediate host, which has been proposed to increase transmission to their definitive host. This behavioural change could result from the parasite actively manipulating its host, but could also be explained by a mechanical effect, where the physical presence of the parasite affects host behaviour. We created an artificial internal parasite using silicone injections in the body cavity to test this mechanical effect hypothesis. We used the Schistocephalus solidus and threespine stickleback ( Gasterosteus aculeatus ) system, as this cestode can reach up to 92% of its fish host mass. Our results suggest that the mass burden brought by this macroparasite alone is not sufficient to cause behavioural changes in its host. Furthermore, our results show that wall-hugging (thigmotaxis), a measure of anxiety in vertebrates, is significantly reduced in Schistocephalus -infected sticklebacks, unveiling a new altered component of behaviour that may result from manipulation by this macroparasite.
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testing the parasite mass burden effect on host behaviour alteration in the Schistocephalus stickleback system
bioRxiv, 2017Co-Authors: Lucie Grecias, Julie Valentin, Nadia AubinhorthAbstract:Many parasites with complex life cycles modify their intermediate host9s behaviour, which has been proposed to increase transmission to their definitive host. This behavioural change could result from the parasite actively manipulating its host, but could also be explained by a mechanical effect, where the parasite9s physical presence affects host behaviour. We created an artificial internal parasite using silicone injections in the body cavity to test this mechanical effect hypothesis. We used the Schistocephalus solidus - threespine stickleback (Gasterosteus aculeatus) system, as this cestode can reach up to 92% of its fish host mass. Our results suggest that the mass burden brought by this macroparasite alone is not sufficient to cause behavioural changes in its host. Furthermore, our results show that wall-hugging (thigmotaxis), a measure of anxiety in vertebrates, is significantly reduced in Schistocephalus-infected sticklebacks, unveiling a new altered component of behaviour that may result from manipulation by this macroparasite.
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transcriptome sequences spanning key developmental states as a resource for the study of the cestode Schistocephalus solidus a threespine stickleback parasite
GigaScience, 2016Co-Authors: Francois Olivier Hebert, Iain Barber, Stephan Grambauer, Christian R Landry, Nadia AubinhorthAbstract:Background Schistocephalus solidus is a well-established model organism for studying the complex life cycle of cestodes and the mechanisms underlying host-parasite interactions. However, very few large-scale genetic resources for this species are available. We have sequenced and de novo-assembled the transcriptome of S. solidus using tissues from whole worms at three key developmental states - non-infective plerocercoid, infective plerocercoid and adult plerocercoid - to provide a resource for studying the evolution of complex life cycles and, more specifically, how parasites modulate their interactions with their hosts during development.
