Robert Poulin

University of Otago, Taieri, Otago, New Zealand

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Publications (489)1451.46 Total impact

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    ABSTRACT: Species of Apatemon Szidat, 1928 and Australapatemon Sudarikov, 1959 are reported from New Zealand for the first time, and their life cycles are resolved using molecular sequence data (28S and ITS rDNA regions and mitochondrial COI). The metacercaria of Apatemon sp. 'jamiesoni' ex Gobiomorphus cotidianus and its cercaria ex Potamopyrgus antipodarum are described in detail. Its adult, found in Anas platyrhynchos and Phalacrocorax punctatus, is identified by molecular sequence data. Apatemon sp. 'jamiesoni' uses a different species of snail host, exhibits consistent differences in the genetic markers examined and its single described adult differs from known species so as to be considered distinct, but its formal description awaits additional adult specimens. Australapatemon niewiadomski n. sp. is described from Anas platyrhynchos. It is distinguished morphologically by the absence of a ringnapf and its overall smaller size compared to most other Australapatemon spp. except Au. magnacetabulum and Au. minor, which are smaller in nearly all features than the new species. Au. niewiadomski n. sp. metacercaria and its intermediate host (Barbronia weberi) are identified via matching of molecular sequence data. The status of Apatemon and Australapatemon as distinct genera is confirmed based on their respective monophyly, and genetic divergence between them is comparable to other well-established genera in the Strigeidae. The diagnosis of Australapatemon is emended. Life history data, accurate patterns of host specialisation and distribution, alongside concurrent molecular and morphological evidence would be useful for an integrative taxonomical approach towards the elucidation of species diversity in this group.
    Parasitology Research 09/2015; DOI:10.1007/s00436-015-4744-0 · 2.10 Impact Factor
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    Katie O'Dwyer · Robert Poulin
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    ABSTRACT: When hosts experience environmental stress, the quantity and quality of resources they provide for parasites may be diminished, and host longevity may be decreased. Under stress, parasites may adopt alternative strategies to avoid fitness reductions. Trematode parasites typically have complex life cycles, involving asexual reproduction in a gastropod first intermediate host. A rare phenomenon, briefly mentioned in the literature, and termed 'precocious encystment' involves the next stage in the parasites' life cycle (metacercarial cyst) forming within the preceding stage (redia), while still inside the snail. In the trematode Parorchis sp. NZ using rocky shore snails exposed to long periods outside water, we hypothesised this might be an adaptive strategy against desiccation, preventing parasite emergence from the snail. To test this, we first investigated the effect of prolonged desiccation on the survival of two species of high intertidal snails. Secondly, we measured the reproductive output (cercarial production) of the parasite under wet and dry conditions. Finally, we quantified the influence of desiccation stress on the occurrence of precocious encystment. Snail mortality was higher under dry conditions, indicating stress, and it was somewhat exacerbated for infected snails. Parasite reproductive output differed between wet and dry conditions, with parasites of snails kept in dry conditions producing more cercariae when placed in water. Little variation was observed in the occurrence of precocious encystment, although some subtle patterns emerged. Given the stresses associated with living in high intertidal environments, we discuss precocious encystment as a possible stress response in this trematode parasite.
    Parasitology International 09/2015; DOI:10.1016/j.parint.2015.09.001 · 1.86 Impact Factor
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    Clement Lagrue · Robert Poulin
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    ABSTRACT: In many host–parasite systems, infection risk can be reduced by high local biodiversity, though the mitigating effects of diversity are context dependent and not universal.In aquatic ecosystems, local fauna can reduce the transmission success of parasite free-swimming infective stages by preying on them, acting as decoy hosts, or physically interfering with transmission. However, most prior research has focused on the effect of a single non-host organism at a time and/or has been performed under simplified and artificial conditions.Here, using data on 11 trematode species sampled in different New Zealand lakes, we test whether local biodiversity affects infection risk in target second intermediate hosts, as well as total parasite population size (number of parasites per m2), under natural conditions. We considered four components of local biodiversity: total biomass of non-host fish species, diversity (Simpson index) of non-host benthic invertebrates, total density of zooplankton and macrophyte biomass. Our analyses also accounted for host density, a known determinant of parasite prevalence, intensity of infection and total parasite population density.The only influence of local biodiversity we detected was a negative effect of the diversity of non-host benthic invertebrates on the prevalence achieved by trematodes in their second intermediate hosts: that is, the proportion of individual hosts that are infected. Interestingly, this effect was discernible in all 11 trematode species considered here, even if very weak within some species.Our findings suggest that higher non-host benthic diversity may generally decrease infection risk for target hosts including snails, arthropods and fish. However, reduced infection success did not automatically mean smaller overall parasite population size, as other factors can maintain the parasite population in the face of high local diversity of non-hosts.
    Freshwater Biology 09/2015; DOI:10.1111/fwb.12677 · 2.74 Impact Factor
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    C. Lagrue · R. Poulin
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    ABSTRACT: A fish body condition index was calculated twice for each individual fish, including or excluding parasite mass from fish body mass, and index values were compared to test the effects of parasite mass on measurement of body condition. Potential correlations between parasite load and the two alternative fish condition index values were tested to assess how parasite mass may influence the perception of the actual effects of parasitism on fish body condition. Helminth parasite mass was estimated in common bully Gobiomorphus cotidianus from four New Zealand lakes and used to assess the biasing effects of parasite mass on body condition indices. Results showed that the inclusion or exclusion of parasite mass from fish body mass in index calculations significantly influenced correlation patterns between parasite load and fish body condition indices. When parasite mass was included, there was a positive correlation between parasite load and fish body condition, seemingly indicating that fish in better condition supported higher parasite loads. When parasite mass was excluded, there was no correlation between parasite load and fish body condition, i.e. there was no detectable effect of helminth parasites on fish condition or fish condition on parasite load. Fish body condition tended to be overestimated when parasite mass was not accounted for; results showed a positive correlation between relative parasite mass and the degree to which individual fish condition was overestimated. Regardless of the actual effects of helminth parasites on fish condition, parasite mass contained within a fish should be taken into account when estimating fish condition. Parasite tissues are not host tissues and should not be included in fish mass when calculating a body condition index, especially when looking at potential effects of helminth infections on fish condition. © 2015 The Fisheries Society of the British Isles.
    Journal of Fish Biology 08/2015; DOI:10.1111/jfb.12749 · 1.66 Impact Factor
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    Clément Lagrue · Robert Poulin
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    ABSTRACT: The standing crop biomass of different populations or trophic levels reflects patterns of energy flow through an ecosystem. The contribution of parasites to total biomass is often considered negligible; recent evidence suggests otherwise, although it comes from a narrow range of natural systems. Quantifying how local parasite biomass, whether that of a single species or an assemblage of species sharing the same host, varies across localities with host population biomass, is critical to determine what constrains parasite populations. We use an extensive dataset on all free-living and parasitic metazoan species from multiple sites in New Zealand lakes to measure parasite biomass and test how it covaries with host biomass. In all lakes, trematodes had the highest combined biomass among parasite taxa, ranging from about 0.01 to 0.25 g m−2, surpassing the biomass of minor free-living taxa. Unlike findings from other studies, the life stage contributing the most to total trematode biomass was the metacercarial stage in the second intermediate host, and not sporocysts or rediae within snail first intermediate hosts, possibly due to low prevalence and small snail sizes. For populations of single parasite species, we found no relationship between host and parasite biomass for either juvenile or adult nematodes. In contrast, all life stages of trematodes had local biomasses that correlated positively with those of their hosts. For assemblages of parasite species sharing the same host, we found strong relationships between local host population biomass and the total biomass of parasites supported. In these host–parasite biomass relationships, the scaling factor (slope in log-log space) suggests that parasites may not be making full use of available host resources. Host populations appear capable of supporting a little more parasite biomass, and may be open to expansion of existing parasites or invasion by new ones.
    Ecography 07/2015; DOI:10.1111/ecog.01720 · 4.77 Impact Factor
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    C Lagrue · R Poulin
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    ABSTRACT: Within any parasite species, abundance varies spatially, reaching higher values in certain localities than in others, presumably reflecting the local availability of host resources or the local suitability of habitat characteristics for free-living stages. In the absence of strong interactions between two species of helminths with complex life cycles, we might predict that the degree to which their abundances covary spatially is determined by their common resource requirements, i.e. how many host species they share throughout their life cycles. We test this prediction using five trematode species, all with a typical three-host cycle, from multiple lake sampling sites in New Zealand's South Island: Stegodexamene anguillae, Telogaster opisthorchis, Coitocaecum parvum, Maritrema poulini, and an Apatemon sp. Pairs of species from this set of five share the same host species at either one, two, or all three life cycle stages. Our results show that when two trematode species share the same host species at all three life stages, they show positive spatial covariation in abundance (of metacercarial and adult stages) across localities. When they share hosts at two life stages, they show positive spatial covariation in abundance in some cases but not others. Finally, if two trematode species share only one host species, at a single life stage, their abundances do not covary spatially. These findings indicate that the extent of resource sharing between parasite species can drive the spatial match-mismatch between their abundances, and thus influence their coevolutionary dynamics and the degree to which host populations suffer from additive or synergistic effects of multiple infections.
    Parasitology Research 06/2015; 114(10). DOI:10.1007/s00436-015-4590-0 · 2.10 Impact Factor
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    Clément Lagrue · Robert Poulin
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    ABSTRACT: Theory predicts the bottom–up coupling of resource and consumer densities, and epidemiological models make the same prediction for host–parasite interactions. Empirical evidence that spatial variation in local host density drives parasite population density remains scarce, however. We test the coupling of consumer (parasite) and resource (host) populations using data from 310 populations of metazoan parasites infecting invertebrates and fish in New Zealand lakes, spanning a range of transmission modes. Both parasite density (no. parasites per m2) and intensity of infection (no. parasites per infected hosts) were quantified for each parasite population, and related to host density, spatial variability in host density and transmission mode (egg ingestion, contact transmission or trophic transmission). The results show that dense and temporally stable host populations are exploited by denser and more stable parasite populations. For parasites with multi-host cycles, density of the ‘source’ host did not matter: only density of the current host affected parasite density at a given life stage. For contact-transmitted parasites, intensity of infection decreased with increasing host density. Our results support the strong bottom–up coupling of consumer and resource densities, but also suggest that intraspecific competition among parasites may be weaker when hosts are abundant: high host density promotes greater parasite population density, but also reduces the number of conspecific parasites per individual host.
    Oikos 04/2015; DOI:10.1111/oik.02164 · 3.44 Impact Factor
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    C D MacLeod · R Poulin
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    ABSTRACT: Ocean acidification (OA) is predicted to cause major changes in marine ecosystem structure and function over the next century, as species-specific tolerances to acidified seawater may alter previously stable relationships between coexisting organisms. Such differential tolerances could affect marine host-parasite associations, as either host or parasite may prove more susceptible to the stressors associated with OA. Despite their important role in many ecological processes, parasites have not been studied in the context of OA. We tested the effects of low pH seawater on the cercariae and, where possible, the metacercariae of four species of marine trematode parasite. Acidified seawater (pH 7.6 and 7.4, 12.5°C) caused a 40 - 60% reduction in cercarial longevity and a 0 - 78% reduction in metacercarial survival. However, the reduction in longevity and survival varied distinctly between parasite taxa, indicating that the effects of reduced pH may be species-specific. These results suggest that OA has the potential to reduce the transmission success of many trematode species, decrease parasite abundance and alter the fundamental regulatory role of multi-host parasites in marine ecosystems. Copyright © 2015. Published by Elsevier Ltd.
    International journal for parasitology 03/2015; 45(7). DOI:10.1016/j.ijpara.2015.02.007 · 3.87 Impact Factor
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    Robert Poulin · Clément Lagrue
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    ABSTRACT: The fundamental assumption underpinning the evolution of numerous adaptations shown by parasites with complex life cycles is that huge losses are incurred by infective stages during certain transmission steps. However, the magnitude of transmission losses or changes in the standing crop of parasites passing from upstream (source) to downstream (target) hosts have never been quantified in nature. Here, using data from 100 pairs of successive upstream–downstream life stages, from distinct populations representing 10 parasite species, we calculated the total density per m 2 of successive life stages. We show that clonal amplification of trematodes in their first intermediate host leads to an average 4-fold expansion of numbers of individuals at the next life stage, when differences in the longevity of successive life stages are taken into account. In contrast, trophic transmission to the definitive host results in almost no numerical change for trematodes, but possibly in large decreases for acanthocephalans and nematodes, though a correction for longevity was not possible for the latter groups. Also, we only found a positive association between upstream and downstream stage densities for transmission involving free-swimming cercariae in trematodes, suggesting a simple output-recruitment process. For trophic transmission, there was no coupling between downstream and upstream parasite densities. These first quantitative estimates of ontogenetic rises and falls in numbers under natural conditions provide new insights into the selective pressures acting on parasites with complex cycles.
    Parasitology 01/2015; 142(06):1-9. DOI:10.1017/S0031182014001917 · 2.56 Impact Factor
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    Clément Lagrue · Robert Poulin · Joel E Cohen
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    ABSTRACT: How do the lifestyles (free-living unparasitized, free-living parasitized, and parasitic) of animal species affect major ecological power-law relationships? We investigated this question in metazoan communities in lakes of Otago, New Zealand. In 13,752 samples comprising 1,037,058 organisms, we found that species of different lifestyles differed in taxonomic distribution and body mass and were well described by three power laws: a spatial Taylor's law (the spatial variance in population density was a power-law function of the spatial mean population density); density-mass allometry (the spatial mean population density was a power-law function of mean body mass); and variance-mass allometry (the spatial variance in population density was a power-law function of mean body mass). To our knowledge, this constitutes the first empirical confirmation of variance-mass allometry for any animal community. We found that the parameter values of all three relationships differed for species with different lifestyles in the same communities. Taylor's law and density-mass allometry accurately predicted the form and parameter values of variance-mass allometry. We conclude that species of different lifestyles in these metazoan communities obeyed the same major ecological power-law relationships but did so with parameters specific to each lifestyle, probably reflecting differences among lifestyles in population dynamics and spatial distribution.
    Proceedings of the National Academy of Sciences 12/2014; 112(6). DOI:10.1073/pnas.1422475112 · 9.67 Impact Factor
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    ABSTRACT: Despite their very different historical origins as scientific disciplines, parasitology and marine ecology have already combined successfully to make important contributions to our understanding of the functioning of natural ecosystems. For example, robust assessments of the contribution of parasites to ecosystem biomass and energetics, and of their impact on community-wide biodiversity and food web structure, have all been made for the first time in marine systems. Nevertheless, for the marriage between parasitology and marine ecology to remain fruitful, several challenges must first be overcome. We discuss seven such challenges on the road to a greater synergy between these disciplines: (1) Raising awareness of parasitism as an ecological force by increasing the proportion of articles about parasites and diseases in marine ecology journals; (2) Making greater use of theory and conceptual frameworks from marine ecology to guide parasitological research; (3) Speeding up or at least maintaining the current rate at which marine parasites are found and described; (4) Elucidating a greater proportion of life cycles in all major groups of marine parasites; (5) Increasing the number of host-parasite model systems on which our knowledge is based; (6) Extending parasitological research offshore and into ocean depths; (7) Developing, as needed, new epidemiological theory and transmission models for the marine environment. None of these challenges is insurmountable, and addressing just a few of them should guarantee that parasitology and marine ecology will continue to join forces and make further substantial contributions.
    Journal of Sea Research 11/2014; in press(on-line). DOI:10.1016/j.seares.2014.10.019 · 1.99 Impact Factor
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    ABSTRACT: 1. Meta-analysis has become a standard way of summarizing empirical studies in many fields, including ecology and evolution. In ecology and evolution, meta-analyses comparing two groups (usually experimental and control groups) have almost exclusively focused on comparing the means, using standardized metrics such as Cohen's / Hedges’ d or the response ratio.2. However, an experimental treatment may not only affect the mean but also the variance. Investigating differences in the variance between two groups may be informative, especially when a treatment influences the variance in addition to or instead of the mean.3. In this paper, we propose the effect size statistic, lnCVR (the natural logarithms of the ratio between the coefficients of variation, CV, from two groups), which enables us to meta-analytically compare differences between the variability of two groups. We illustrate the use of lnCVR with examples from ecology and evolution.4. Further, as an alternative approach to the use of lnCVR, we propose the combined use of (the log standard deviation) and (the log mean) in a hierarchical (linear mixed) model. The use of with overcomes potential limitations of lnCVR and it provides a more flexible, albeit more complex, way to examine variation beyond two group comparisons. Relevantly, we also refer to the potential use of and lnCV (the log CV) in the context of comparative analysis.5. Our approaches to compare variability could be applied to already published meta-analytic datasets that compare two-group means to uncover potentially overlooked effects on the variance. Additionally, our approaches should be applied to future meta-analyses, especially when one suspects a treatment has an effect not only on the mean, but also on the variance. Notably, the application of the proposed methods extends beyond the fields of ecology and evolution.This article is protected by copyright. All rights reserved.
    Methods in Ecology and Evolution 11/2014; 6(2). DOI:10.1111/2041-210X.12309 · 6.55 Impact Factor
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    ABSTRACT: Littorinid snails are one particular group of gastropods identified as important intermediate hosts for a wide range of digenean parasite species, at least throughout the Northern Hemisphere. However nothing is known of trematode species infecting these snails in the Southern Hemisphere. This study is the first attempt at cataloguing the digenean parasites infecting littorinids in New Zealand. Examination of over 5,000 individuals of two species of the genus Austrolittorina Rosewater, A. cincta Quoy & Gaimard and A. antipodum Philippi, from intertidal rocky shores, revealed infections with four digenean species representative of a diverse range of families: Philophthalmidae Looss, 1899, Notocotylidae Lühe, 1909, Renicolidae Dollfus, 1939 and Microphallidae Ward, 1901. This paper provides detailed morphological descriptions of the cercariae and intramolluscan stages of these parasites. Furthermore, partial sequences of the 28S rRNA gene and the mitochondrial gene cytochrome c oxidase subunit 1 (cox1) for varying numbers of isolates of each species were obtained. Phylogenetic analyses were carried out at the superfamily level and along with the morphological data were used to infer the generic affiliation of the species.
    Systematic Parasitology 10/2014; 89(2). DOI:10.1007/s11230-014-9515-2 · 1.34 Impact Factor
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    Katie O’Dwyer · Aaron Lynch · Robert Poulin
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    ABSTRACT: For rocky shore gastropods, attachment strength is a key determinant of survival, as getting dislodged by wave action or predators has negative consequences. Yet little is known of the factors that cause inter-individual variation in attachment strength among conspecifics. Here, we test the influence of trematode infection on the suction-mediated attachment strength of periwinkles from two New Zealand species, Austrolittorina cincta and A. antipodum. Using a standardised experimental protocol, we measured both the strength of attachment of individual snails to the substrate, and its repeatability, i.e. the consistency of measurements taken on different occasions on the same individuals. We then compared the attachment of snails infected with a philophthalmid trematode with that of their uninfected conspecifics. First, we found that for a given snail mass, infected snails were easier to detach from the substrate than the uninfected ones, although this pattern was only significant for A. cincta, the larger of the two snail species. Second, the repeatability of attachment strength measurements per individual snail did not differ between infected and uninfected conspecifics, for either of the two periwinkle species. Our findings show that parasitism can weaken snail attachment, and indirectly increase snail mortality, on exposed rocky shores, suggesting a new way in which parasites can affect host population dynamics.
    Journal of Experimental Marine Biology and Ecology 09/2014; 458:1–5. DOI:10.1016/j.jembe.2014.04.022 · 1.87 Impact Factor
  • Devon B Keeney · Jason Palladino · Robert Poulin
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    ABSTRACT: SUMMARY Host specificity is a fundamental component of a parasite's life history. However, accurate assessments of host specificity, and the factors influencing it, can be obscured by parasite cryptic species complexes. We surveyed two congeneric species of intertidal snail intermediate hosts, Zeacumantus subcarinatus and Zeacumantus lutulentus, throughout New Zealand to identify the number of genetically distinct echinostome trematodes infecting them and determine the levels of snail host specificity among echinostomes. Two major echinostome clades were identified: a clade consisting of an unidentified species of the subfamily Himasthlinae and a clade consisting of five species of the genus Acanthoparyphium. All five Acanthoparyphium species were only found in a single snail species, four in Z. subcarinatus and one in Z. lutulentus. In contrast, the Himasthlinae gen. sp. was found in both hosts, but was more prevalent in Z. lutulentus (97 infections) than Z. subcarinatus (10 infections). At least two of the Acanthoparyphium spp. and the Himasthlinae gen. sp. are widespread throughout New Zealand, and can therefore encounter both snail species. Our results suggest that host specificity is determined by host-parasite incompatibilities, not geographic separation, and that it can evolve in different ways in closely related parasite lineages.
    Parasitology 08/2014; 142(02):1-10. DOI:10.1017/S0031182014001279 · 2.56 Impact Factor
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    Isabel Blasco‐Costa · Carlos Rouco · Robert Poulin
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    ABSTRACT: Contrary to species occurrence, little is known about the determinants of spatial patterns of intraspecific variation in abundance, particularly for parasitic organisms. In this study, we provide a multi-faceted overview of spatial patterns in parasite abundance and examine several potential underlying processes. We first tested for a latitudinal gradient in local abundance of the regionally most common parasite species and whether these species achieve higher abundances at the same localities (shared hot spots of infection). Secondly, we tested whether intraspecific similarity in local abundance between sites follows a spatial distance decay pattern or is better explained by variation in extrinsic biotic and abiotic factors between localities related to local parasite transmission success. We examined the infection landscape of a model fish host system (common and upland bullies, genus Gobiomorphus: Eleotridae) across its entire distributional range. We applied general linear models to test the effect of latitude on each species local abundance independently, including the abundance of each co-infecting species as another predictor. We computed multiple regressions on distance matrices among localities based on abundance of each of the four most common trematode species, as well as for geographic distance, biotic and abiotic distinctness of the localities. Our results showed that the most widely distributed parasites of bullies also achieve the highest mean local abundances, following the abundance – occupancy relationship. Variation in local abundance of any focal parasite species was independent of latitude, the abundance of co-occurring species and spatial distance or disparity in biotic attributes between localities. For only one parasite species, similarity of abundance between sites covaried with the extent of abiotic differences between sites. The lack of association between hot spots of infection for co-occurring species reinforces the geographic mosaic scenario in which hosts and parasites coevolve by suggesting non-deterministic, species-specific variation in parasite abundance across space.
    Ecography 08/2014; 38(3). DOI:10.1111/ecog.01020 · 4.77 Impact Factor
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    ABSTRACT: Climates are changing worldwide, and populations are under selection to adapt to these changes. Changing temperature, in particular, can directly impact ectotherms and their parasites, with potential consequences for whole ecosystems. The potential of parasite populations to adapt to climate change largely depends on the amount of genetic variation they possess in their responses to environmental fluctuations. This study is, to our knowledge, the first to look at differences among parasite genotypes in response to temperature, with the goal of quantifying the extent of variation among conspecifics in their responses to increasing temperature. Snails infected with single genotypes of the trematode Maritrema novaezealandensis were sequentially acclimatized to two different temperatures, 'current' (15° C) and 'elevated' (20° C), over long periods. These temperatures are based on current average field conditions in the natural habitat and those predicted to occur during the next few decades. The output and activity of cercariae (free-swimming infective stages emerging from snails) were assessed for each genotype at each temperature. The results indicate that, on average, both cercarial output and activity are higher at the elevated acclimation temperature. More importantly, the output and activity of cercariae are strongly influenced by a genotype-by-temperature interaction, such that different genotypes show different responses to increasing temperature. Both the magnitude and direction (increase or decrease) of responses to temperature varied widely among genotypes. Therefore, there is much potential for natural selection to act on this variation, and predicting how the trematode M. novaezealandensis will respond to the climate changes predicted for the next century will prove challenging.
    International Journal for Parasitology 07/2014; 44(13). DOI:10.1016/j.ijpara.2014.07.002 · 3.87 Impact Factor
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    ABSTRACT: Complexes of cryptic species are rapidly being discovered in many parasite taxa, including trematodes. However, after they are found, cryptic species are rarely distinguished from each other with respect to key ecological or life history traits. In this study, we applied an integrative taxonomic approach to the discovery of cryptic species within Stegodexamene anguillae, a facultatively progenetic trematode common throughout New Zealand. The presence of cryptic species was determined by the genetic divergence found in the mitochondrial cytochrome c oxidase I (COI) gene, the 16S rRNA gene and the nuclear 28S gene, warranting recognition of two distinct species and indicating a possible third species. Speciation was not associated with geographic distribution or microhabitat within the second intermediate host; however frequency of the progenetic reproductive strategy (and the truncated life cycle associated with it) was significantly greater in one of the lineages. Therefore, two lines of evidence, molecular and ecological, support the distinction between these two species and suggest scenarios for their divergence.
    International Journal for Parasitology 07/2014; 44(11). DOI:10.1016/j.ijpara.2014.06.006 · 3.87 Impact Factor
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    ABSTRACT: Statistical correlations of biodiversity patterns across multiple trophic levels have received considerable attention in various types of interacting assemblages, forging a universal understanding of patterns and processes in free-living communities. Host–parasite interactions present an ideal model system for studying congruence of species richness among taxa as obligate parasites are strongly dependent upon the availability of their hosts for survival and reproduction while also having a tight coevolutionary relationship with their hosts. The present meta-analysis examined 38 case studies on the relationship between species richness of hosts and parasites, and is the first attempt to provide insights into the patterns and causal mechanisms of parasite biodiversity at the community level using meta-regression models. We tested the distinct role of resource (i.e. host) availability and evolutionary co-variation on the association between biodiversity of hosts and parasites, while spatial scale of studies was expected to influence the extent of this association. Our results demonstrate that species richness of parasites is tightly correlated with that of their hosts with a strong average effect size (r= 0.55) through both host availability and evolutionary co-variation. However, we found no effect of the spatial scale of studies, nor of any of the other predictor variables considered, on the correlation. Our findings highlight the tight ecological and evolutionary association between host and parasite species richness and reinforce the fact that host–parasite interactions provide an ideal system to explore congruence of biodiversity patterns across multiple trophic levels.
    Ecography 07/2014; 37(7). DOI:10.1111/j.1600-0587.2013.00571.x · 4.77 Impact Factor
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    F Jorge · A Perera · V Roca · M A Carretero · D J Harris · R Poulin
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    ABSTRACT: Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sister genus Skrjabinodon than Spauligodon major males. Because of the level of uncertainty in the results of ancestral state reconstruction, it is unclear if the existence of male dimorphism in this group represents independent instances of convergent evolution or an ancestral trait lost multiple times. Also, although the number of major males per host was positively correlated with the number of females, the same did not hold true for minor males, whose presence was not associated with any other ecological factor. Nevertheless, the existence of male dimorphism in Spauligodon nematodes is tentatively interpreted as resulting from alternative reproductive tactics, with differences in presence and number of individuals as indicators of differences in fitness, with the lower numbers of minor males per host likely maintained by negative frequency-dependent selection.
    Journal of Evolutionary Biology 05/2014; 27(8). DOI:10.1111/jeb.12430 · 3.23 Impact Factor

Publication Stats

13k Citations
1,451.46 Total Impact Points


  • 1993–2015
    • University of Otago
      • Department of Zoology
      Taieri, Otago, New Zealand
  • 2013
    • University of Canberra
      Canberra, Australian Capital Territory, Australia
  • 2005–2013
    • Ben-Gurion University of the Negev
      • The Swiss Institute for Dryland Environmental and Energy Research(SIDEER)
      Be'er Sheva`, Southern District, Israel
    • Universidad Austral de Chile
      Ciudad de Valdivía, Los Ríos, Chile
    • Catholic University of the Most Holy Conception
      • Facultad de Ciencias
      Ciudad de Concepcion, Biobío, Chile
  • 2011–2012
    • University of Vermont
      • Department of Biology
      Burlington, Vermont, United States
  • 2005–2012
    • Universidade Estadual de Maringá
      • Departamento de Biologia
      Maringá, Paraná, Brazil
  • 2010
    • London Natural History Society
      Londinium, England, United Kingdom
    • Universidad Nacional de Mar del Plata
      • Departamento de Biología
      Mar de Plata, Buenos Aires, Argentina
    • Hochschule Koblenz
      Coblenz, Rheinland-Pfalz, Germany
    • Le Moyne College
      Syracuse, New York, United States
  • 2008
    • University of Leicester
      • Department of Biology
      Leicester, ENG, United Kingdom
  • 1991–2005
    • Université du Québec à Montréal
      • Department of Biological Sciences
      Montréal, Quebec, Canada
  • 2004
    • University of Duisburg-Essen
      Essen, North Rhine-Westphalia, Germany
  • 2003
    • Academy of Sciences of the Czech Republic
      Praha, Praha, Czech Republic
  • 1998
    • Carleton University
      • Department of Biology
      Ottawa, Ontario, Canada
  • 1997
    • Université de Montpellier 1
      • Institut des Sciences de l’Évolution Montpellier (ISEM)
      Montpelhièr, Languedoc-Roussillon, France