Prior residency does not always pay off – co-infections in<i>Daphnia</i>

BackgroundAlthough inducible defences have been studied extensively, only little is known about how the presence of parasites might interfere with these anti-predator adaptations. Both parasites and predators are important factors shaping community structure and species composition of ecosystems. Here, we simultaneously exposed Daphnia magna to predator cues (released by the tadpole shrimp, Triops, or by a fish) and spores of the yeast parasite Metschnikowia sp. to determine how life history and morphological inducible defences against these two contrasting types of predators are affected by infection.ResultsThe parasite suppressed some Triops-induced defences: Daphnia lost the ability to produce a greater number of larger offspring, a life-history adaptation to Triops predation. In contrast, the parasite did not suppress inducible defences against fish: induction (resulting in smaller body length of the mothers as well as of their offspring) and infection acted additively on the measured traits. Thus, fish-induced defences may be less costly than inducible defences against small invertebrate predators like Triops; the latter defences could no longer be expressed when the host had already invested in fighting off the parasite.ConclusionsIn summary, our study suggests that as specific inducible defences differ in their costs, some might be suppressed if a target prey is additionally infected. Therefore, adding parasite pressure to predator–prey systems can help to elucidate the costs of inducible defences.

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“…[35-37]]. It seems that the parasite consumes resources that could otherwise be invested into host reproduction and growth [36].…”

Section: Discussionmentioning

confidence: 99%

“…To investigate this question we infected D. magna with the parasite Metschnikowia sp. (family Hemiascomycetes, [34]), which causes major reductions in host life span and fecundity [35-37], and exposed them to two contrasting types of predators, fish and Triops .…”

Section: Introductionmentioning

confidence: 99%

Fighting parasites and predators: How to deal with multiple threats?

et al. 2012

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“…Indeed, most of the evidence on G Â G interactions between unrelated parasite species comes from pairwise infections using single strains (e.g. [23][24][25][26][27]), while there are no experimental studies using a broad range of replicated parasite strains or genotypes.…”

Section: Introductionmentioning

confidence: 99%

Interactions among bacterial strains and fluke genotypes shape virulence of co-infection

et al. 2015

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Most studies of virulence of infection focus on pairwise host-parasite interactions. However, hosts are almost universally co-infected by several parasite strains and/or genotypes of the same or different species. While theory predicts that co-infection favours more virulent parasite genotypes through intensified competition for host resources, knowledge of the effects of genotype by genotype (G Â G) interactions between unrelated parasite species on virulence of co-infection is limited. Here, we tested such a relationship by challenging rainbow trout with replicated bacterial strains and fluke genotypes both singly and in all possible pairwise combinations. We found that virulence (host mortality) was higher in co-infections compared with single infections. Importantly, we also found that the overall virulence was dependent on the genetic identity of the co-infecting partners so that the outcome of co-infection could not be predicted from the respective virulence of single infections. Our results imply that G Â G interactions among co-infecting parasites may significantly affect host health, add to variance in parasite fitness and thus influence evolutionary dynamics and ecology of disease in unexpected ways.

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“…The strength of the interactions depends on many different factors, such as host behavior (Bush and Malenke 2008), the infection dose to which the host is exposed (Fellous and Koella 2009), or the order in which multiple infections occur (Lohr et al. 2010; Hoverman et al. 2013).…”

Section: Introductionmentioning

confidence: 99%

Diet quality determines interspecific parasite interactions in host populations

Lange

Reuter

Ebert

et al. 2014

Ecology and Evolution

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The widespread occurrence of multiple infections and the often vast range of nutritional resources for their hosts allow that interspecific parasite interactions in natural host populations might be determined by host diet quality. Nevertheless, the role of diet quality with respect to multispecies parasite interactions on host population level is not clear. We here tested the effect of host population diet quality on the parasite community in an experimental study using Daphnia populations. We studied the effect of diet quality on Daphnia population demography and the interactions in multispecies parasite infections of this freshwater crustacean host. The results of our experiment show that the fitness of a low-virulent microsporidian parasite decreased in low, but not in high-host-diet quality conditions. Interestingly, infections with the microsporidium protected Daphnia populations against a more virulent bacterial parasite. The observed interspecific parasite interactions are discussed with respect to the role of diet quality-dependent changes in host fecundity. This study reflects that exploitation competition in multispecies parasite infections is environmentally dependent, more in particular it shows that diet quality affects interspecific parasite competition within a single host and that this can be mediated by host population-level effects.

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Prior residency does not always pay off – co-infections inDaphnia

Cited by 50 publications

References 46 publications

Fighting parasites and predators: How to deal with multiple threats?

Fighting parasites and predators: How to deal with multiple threats?

Interactions among bacterial strains and fluke genotypes shape virulence of co-infection

Diet quality determines interspecific parasite interactions in host populations

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