Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size

Background Parasites are essential components of natural communities, but the factors that generate skewed distributions of parasite occurrences and abundances across host populations are not well understood. Methods Here, we analyse at a seascape scale the spatiotemporal relationships of parasite exposure and host body-size with the proportion of infected hosts (i.e., prevalence) and aggregation of parasite burden across ca. 150 km of the coast and over 22 months. We predicted that the effects of parasite exposure on prevalence and aggregation are dependent on host body-sizes. We used an indirect host-parasite interaction in which migratory seagulls, sandy-shore molecrabs, and an acanthocephalan worm constitute the definitive hosts, intermediate hosts, and endoparasite, respectively. In such complex systems, increments in the abundance of definitive hosts imply increments in intermediate hosts’ exposure to the parasite’s dispersive stages. Results Linear mixed-effects models showed a significant, albeit highly variable, positive relationship between seagull density and prevalence. This relationship was stronger for small (cephalothorax length >15 mm) than large molecrabs (<15 mm). Independently of seagull density, large molecrabs carried significantly more parasites than small molecrabs. The analysis of the variance-to-mean ratio of per capita parasite burden showed no relationship between seagull density and mean parasite aggregation across host populations. However, the amount of unexplained variability in aggregation was strikingly higher in larger than smaller intermediate hosts. This unexplained variability was driven by a decrease in the mean-variance scaling in heavily infected large molecrabs. Conclusions These results show complex interdependencies between extrinsic and intrinsic population attributes on the structure of host-parasite interactions. We suggest that parasite accumulation—a characteristic of indirect host-parasite interactions—and subsequent increasing mortality rates over ontogeny underpin size-dependent host-parasite dynamics.

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Peer Review #1 of "Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size (v0.2)"

10.7287/peerj.3675v0.2/reviews/1 ◽

2017 ◽

Author(s):

B Lester

Keyword(s):

Body Size ◽

Intermediate Host ◽

Peer Review ◽

Spatiotemporal Variability ◽

Host Body ◽

Host Parasite ◽

Host Body Size

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Peer Review #2 of "Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size (v0.1)"

10.7287/peerj.3675v0.1/reviews/2 ◽

2017 ◽

Keyword(s):

Body Size ◽

Intermediate Host ◽

Peer Review ◽

Spatiotemporal Variability ◽

Host Body ◽

Host Parasite ◽

Host Body Size

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Peer Review #1 of "Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size (v0.1)"

10.7287/peerj.3675v0.1/reviews/1 ◽

2017 ◽

Author(s):

B Lester

Keyword(s):

Body Size ◽

Intermediate Host ◽

Peer Review ◽

Spatiotemporal Variability ◽

Host Body ◽

Host Parasite ◽

Host Body Size

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The role of ecological opportunity in shaping host–parasite networks

Parasitology ◽

10.1017/s003118202000133x ◽

2020 ◽

Vol 147 (13) ◽

pp. 1452-1460

Author(s):

Elvira D'Bastiani ◽

Karla M. Campião ◽

Walter A. Boeger ◽

Sabrina B. L. Araújo

Keyword(s):

Body Size ◽

Theoretical Models ◽

Interaction Networks ◽

Ecological Opportunity ◽

Host Body ◽

Seasonally Flooded ◽

Brazilian Pantanal ◽

Host Parasite ◽

Host Body Size

AbstractDespite the great interest to quantify the structure of host–parasite interaction networks, the real influence of some factors such as taxonomy, host body size and ecological opportunity remains poorly understood. In this paper, we investigate the general patterns of organization and structure of interactions in two anuran–parasite networks in the Brazilian Pantanal (seasonally flooded environment) and Atlantic Forest (non-flooded forest). We present theoretical models to test whether the structures of these host–parasite interaction networks are influenced by neutrality, host taxonomy and host body size. Subsequently, we calculated metrics of connectance, nestedness and modularity to characterize the network structure. We demonstrated the structure networks were influenced mainly by body size and taxonomy of the host. Moreover, our results showed that the seasonally flooded environment present networks with higher connectance/nestedness and lower modularity compared to the other environment. The results also suggest that seasonal floods may promote ecological opportunities for new species associations.

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A Few Good Reasons Why Species-Area Relationships Do Not Work for Parasites

BioMed Research International ◽

10.1155/2014/271680 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 8

Author(s):

Giovanni Strona ◽

Simone Fattorini

Keyword(s):

Species Richness ◽

Body Size ◽

Parasite Species ◽

Enemy Release ◽

Parasite Species Richness ◽

Host Body ◽

Ecological Features ◽

Species Area ◽

Host Parasite ◽

Host Body Size

Several studies failed to find strong relationships between the biological and ecological features of a host and the number of parasite species it harbours. In particular, host body size and geographical range are generally only weak predictors of parasite species richness, especially when host phylogeny and sampling effort are taken into account. These results, however, have been recently challenged by a meta-analytic study that suggested a prominent role of host body size and range extent in determining parasite species richness (species-area relationships). Here we argue that, in general, results from meta-analyses should not discourage researchers from investigating the reasons for the lack of clear patterns, thus proposing a few tentative explanations to the fact that species-area relationships are infrequent or at least difficult to be detected in most host-parasite systems. The peculiar structure of host-parasite networks, the enemy release hypothesis, the possible discrepancy between host and parasite ranges, and the evolutionary tendency of parasites towards specialization may explain why the observed patterns often do not fit those predicted by species-area relationships.

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Explaining variability in parasite aggregation levels among host samples

Parasitology ◽

10.1017/s0031182012002053 ◽

2013 ◽

Vol 140 (4) ◽

pp. 541-546 ◽

Cited By ~ 85

Author(s):

ROBERT POULIN

Keyword(s):

Body Size ◽

Strong Relationship ◽

Host Susceptibility ◽

Helminth Parasites ◽

Susceptibility To Infection ◽

Host Body ◽

Parasite Aggregation ◽

Using Data ◽

Species Specific ◽

Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

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Host-parasite interactions between the piranha Pygocentrus nattereri (Characiformes: Characidae) and isopods and branchiurans (Crustacea) in the rio Araguaia basin, Brazil

Neotropical Ichthyology ◽

10.1590/s1679-62252004000200006 ◽

2004 ◽

Vol 2 (2) ◽

pp. 93-98 ◽

Cited By ~ 10

Author(s):

Lucélia Nobre Carvalho ◽

Rafael Arruda ◽

Kleber Del-Claro

Keyword(s):

Body Size ◽

Mean Intensity ◽

Feeding Sites ◽

Host Parasite Interactions ◽

Ecological Aspects ◽

Field Samples ◽

Pygocentrus Nattereri ◽

The Tropics ◽

Host Parasite ◽

Ventral Area

In the tropics, studies on the ecology of host-parasite interactions are incipient and generally related to taxonomic aspects. The main objective of the present work was to analyze ecological aspects and identify the metazoan fauna of ectoparasites that infest the piranha, Pygocentrus nattereri. In May 2002, field samples were collected in the rio Araguaia basin, State of Goiás (Brazil). A total of 252 individuals of P. nattereri were caught with fishhooks and 32.14% were infested with ectoparasite crustaceans. The recorded ectoparasites were branchiurans, Argulus sp. and Dolops carvalhoi and the isopods Braga patagonica, Anphira branchialis and Asotana sp. The prevalence and mean intensity of branchiurans (16.6% and 1.5, respectively) and isopods (15.5% and 1.0, respectively) were similar. Isopods were observed in the gills of the host; branchiurans were more frequent where the skin was thinner, and facilitated attachment and feeding. The ventral area, the base of the pectoral fin and the gular area were the most infested areas. The correlations between the standard length of the host and the variables intensity and prevalence of crustaceans parasitism, were significant only for branchiurans (rs = 0.2397, p = 0.0001; chi2 = 7.97; C = 0.19). These results suggest that both feeding sites and body size probably play an important role in the distribution and abundance of ectoparasites.

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