Parasitism alters three power laws of scaling in a metazoan community: Taylor’s law, density-mass allometry, and variance-mass allometry

Lagrue, Clément; Poulin, Robert; Cohen, Joel E.

doi:10.1073/pnas.1422475112

Cited by 51 publications

(51 citation statements)

References 23 publications

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“…An earlier study about individual trees also found that the scaling exponent did not fall within the proposed range (Cohen et al, 2012). Differences in the scaling exponents may reflect the ability of differing life habits (e.g., parasitism or epidemic infection) to alter power laws (Lagrue, Poulin, & Cohen, 2015;Morand & Krasnov, 2008). Arruda-Neto et al (2012) indicated that the scaling exponent (1< exponent <2) is intimately associated with long-range interactions among all the elements of a given system, plus negative interactions among them within a community.…”

Section: Discussionmentioning

confidence: 92%

Power Laws in Cone Production of Longleaf Pine across Its Native Range in the United States

Chen¹,

Guo²,

Brockway³

2017

SAR

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Longleaf pine (Pinus palustris Mill.) forests in the southeastern United States are considered endangered ecosystems, because of their dramatic decrease in area since European colonization and poor rates of recovery related to episodic natural regeneration. Sporadic seed production constrains restoration efforts and complicates sustainable management of this species. Previous studies of other tree species found invariant scaling properties in seed output. Here, using long-term monitoring data for cone production at seven sites across the native range of longleaf pine, we tested the possible presence of two types of power laws. Findings indicate that (i) the frequency distribution of cone production at seven sites, from 1958 to 2014, follows power law relationships with high level of significance; (ii) although there is no general trend in the dynamics of scaling exponents among all sites, there are dynamics of scaling exponents at each site, with sudden changes in scaling exponents generally corresponding to the years of higher or lower cone production; and (iii) Taylor"s power laws explain cone production at different locations, but the scaling exponents vary among these. Results from this computational approach provide new insight into the irregular cone production of longleaf pine at spatial and temporal scales. Integrated ecosystem monitoring will be necessary to more fully understand future changes in cone production.

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Section: Discussionmentioning

confidence: 92%

Power Laws in Cone Production of Longleaf Pine across Its Native Range in the United States

Chen¹,

Guo²,

Brockway³

2017

SAR

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“…Here, we do not use the data on free-living species without parasites. As noted above, unparasitized free-living species had different body size distributions and taxonomic distributions from both parasites and hosts (13). Based on large sample sizes and careful searches for parasites within free-living species, we think that it is unlikely that our distinction between hosts and unparasitized free-living species is artifactual.…”

Section: [9]mentioning

confidence: 82%

“…15, p. 543), each value of θ specified one pair of (mean abundance per host, variance of abundance per host) of helminth parasites of fish from 410 samples (with 180 parasitic helminth species and 68 fish host species from 62 different published papers). In our earlier test of TL (13), each value of θ specified one pair of (mean population density per square meter, variance of population density per square meter) from a specified lake sampled in a specified season counting a specified species of parasite (253 mean-variance pairs) or host (151 mean-variance pairs).…”

Section: Theoretical Methods and Resultsmentioning

confidence: 99%

“…This measure of population density enabled them to compare allometric power laws in parasitic and freeliving species. Measuring population density by individuals·meter −2 , Lagrue et al (13) showed that the variance and mean of population density were well approximated by 1 but that the parameters a and b differed among three so-called "lifestyles": parasites, free-living species that were hosts of parasites (henceforth called "hosts" here), and unparasitized free-living species.…”

Section: Significancementioning

confidence: 99%

“…Lagrue et al (13) described the field sites and the methods of collecting the data. In brief, all metazoan species in the littoral zones of four lakes in Otago, New Zealand were collected and classified as parasitic, free-living with parasites (here hosts), and free-living without parasites.…”

Section: [9]mentioning

confidence: 99%

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Linking parasite populations in hosts to parasite populations in space through Taylor's law and the negative binomial distribution

Cohen

Poulin

Lagrue

2016

Proc. Natl. Acad. Sci. U.S.A.

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The spatial distribution of individuals of any species is a basic concern of ecology. The spatial distribution of parasites matters to control and conservation of parasites that affect human and nonhuman populations. This paper develops a quantitative theory to predict the spatial distribution of parasites based on the distribution of parasites in hosts and the spatial distribution of hosts. Four models are tested against observations of metazoan hosts and their parasites in littoral zones of four lakes in Otago, New Zealand. These models differ in two dichotomous assumptions, constituting a 2 × 2 theoretical design. One assumption specifies whether the variance function of the number of parasites per host individual is described by Taylor's law (TL) or the negative binomial distribution (NBD). The other assumption specifies whether the numbers of parasite individuals within each host in a square meter of habitat are independent or perfectly correlated among host individuals. We find empirically that the variance–mean relationship of the numbers of parasites per square meter is very well described by TL but is not well described by NBD. Two models that posit perfect correlation of the parasite loads of hosts in a square meter of habitat approximate observations much better than two models that posit independence of parasite loads of hosts in a square meter, regardless of whether the variance–mean relationship of parasites per host individual obeys TL or NBD. We infer that high local interhost correlations in parasite load strongly influence the spatial distribution of parasites. Local hotspots could influence control and conservation of parasites.

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Estimating the magnitude and sensitivity of energy fluxes for stickleback hosts and Schistocephalus solidus parasites using the metabolic theory of ecology

Claar,

Faiad,

Mastick

et al. 2023

Ecology and Evolution

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Parasites are ubiquitous, yet their effects on hosts are difficult to quantify and generalize across ecosystems. One promising metric of parasitic impact uses the metabolic theory of ecology (MTE) to calculate energy flux, an estimate of energy lost to parasites. We investigated the feasibility of using metabolic scaling rules to compare the energetic burden of parasitism among individuals. Specifically, we found substantial sensitivity of energy flux estimates to input parameters used in the MTE equation when using available data from a model host–parasite system (Gasterosteus aculeatus and Schistocephalus solidus). Using literature values, size data from parasitized wild fish, and a respirometry experiment, we estimate that a single S. solidus tapeworm may extract up to 32% of its stickleback host's baseline metabolic energy requirement, and that parasites in multiple infections may collectively extract up to 46%. The amount of energy siphoned from stickleback to tapeworms is large but did not instigate an increase in respiration rate in the current study. This emphasizes the importance of future work focusing on how parasites influence ecosystem energetics. The approach of using the MTE to calculate energy flux provides great promise as a quantitative foundation for such estimates and provides a more concrete metric of parasite impact on hosts than parasite abundance alone.

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Parasitism alters three power laws of scaling in a metazoan community: Taylor’s law, density-mass allometry, and variance-mass allometry

Cited by 51 publications

References 23 publications

Power Laws in Cone Production of Longleaf Pine across Its Native Range in the United States

Power Laws in Cone Production of Longleaf Pine across Its Native Range in the United States

Linking parasite populations in hosts to parasite populations in space through Taylor's law and the negative binomial distribution

Estimating the magnitude and sensitivity of energy fluxes for stickleback hosts and Schistocephalus solidus parasites using the metabolic theory of ecology

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