scholarly journals Biodiversity loss decreases parasite diversity: theory and patterns

2012 ◽  
Vol 367 (1604) ◽  
pp. 2814-2827 ◽  
Author(s):  
Kevin D. Lafferty
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Biodiversity Loss ◽  
Parasite Diversity ◽  
Free Living ◽  
Parasite Richness ◽  
Living Species ◽  
Host Parasite ◽  
Food Web Complexity ◽  
The Relationship

Past models have suggested host–parasite coextinction could lead to linear, or concave down relationships between free-living species richness and parasite richness. I explored several models for the relationship between parasite richness and biodiversity loss. Life cycle complexity, low generality of parasites and sensitivity of hosts reduced the robustness of parasite species to the loss of free-living species diversity. Food-web complexity and the ordering of extinctions altered these relationships in unpredictable ways. Each disassembly of a food web resulted in a unique relationship between parasite richness and the richness of free-living species, because the extinction trajectory of parasites was sensitive to the order of extinctions of free-living species. However, the average of many disassemblies tended to approximate an analytical model. Parasites of specialist hosts and hosts higher on food chains were more likely to go extinct in food-web models. Furthermore, correlated extinctions between hosts and parasites (e.g. if parasites share a host with a specialist predator) led to steeper declines in parasite richness with biodiversity loss. In empirical food webs with random removals of free-living species, the relationship between free-living species richness and parasite richness was, on average, quasi-linear, suggesting biodiversity loss reduces parasite diversity more than previously thought.

scholarly journals Untangling the roles of parasites in food webs with generative network models

2015 ◽  
Author(s):  
Abigail Z. Jacobs ◽  
Jennifer A. Dunne ◽  
Cristopher Moore ◽  
Aaron Clauset
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Statistical Physics ◽  
Network Models ◽  
Food Web Structure ◽  
Free Living ◽  
Web Structure ◽  
Living Species ◽  
Parasitic Interactions ◽  
The Impact

Food webs represent the set of consumer-resource interactions among a set of species that co-occur in a habitat, but most food web studies have omitted parasites and their interactions. Recent studies have provided conflicting evidence on whether including parasites changes food web structure, with some suggesting that parasitic interactions are structurally distinct from those among free-living species while others claim the opposite. Here, we describe a principled method for understanding food web structure that combines an efficient optimization algorithm from statistical physics called parallel tempering with a probabilistic generalization of the empirically well-supported food web niche model. This generative model approach allows us to rigorously estimate the degree to which interactions that involve parasites are statistically distinguishable from interactions among free-living species, whether parasite niches behave similarly to free-living niches, and the degree to which existing hypotheses about food web structure are naturally recovered. We apply this method to the well-studied Flensburg Fjord food web and show that while predation on parasites, concomitant predation of parasites, and parasitic intraguild trophic interactions are largely indistinguishable from free-living predation interactions, parasite-host interactions are different. These results provide a powerful new tool for evaluating the impact of classes of species and interactions on food web structure to shed new light on the roles of parasites in food webs.

scholarly journals Anti-predator defence and the complexity–stability relationship of food webs

2007 ◽  
Vol 274 (1618) ◽  
pp. 1617-1624 ◽  
Author(s):  
Michio Kondoh
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Food Webs ◽  
Community Level ◽  
Negative Effects ◽  
Food Web Structure ◽  
Wide Range ◽  
The Stability ◽  
Food Web Complexity ◽  
Predator Defence

The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey–predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity–stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance–stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance–stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.

scholarly journals Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

2009 ◽  
Vol 364 (1524) ◽  
pp. 1659-1663 ◽  
Author(s):  
Kevin D. Lafferty ◽  
Armand M. Kuris
Keyword(s):  
Food Web ◽  
Trematode Species ◽  
Snail Species ◽  
Native Community ◽  
Free Living ◽  
Predator Prey ◽  
Living Species ◽  
Secondary Parasite ◽  
Disproportionate Number ◽  
Secondary Extinction

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica , resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria , is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

scholarly journals Eutrophication, biodiversity loss, and species invasions modify the relationship between host and parasite richness during host community assembly

2020 ◽  
Vol 26 (9) ◽  
pp. 4854-4867 ◽  
Author(s):  
Fletcher W. Halliday ◽  
Robert W. Heckman ◽  
Peter A. Wilfahrt ◽  
Charles E. Mitchell
Keyword(s):  
Community Assembly ◽  
Biodiversity Loss ◽  
Host Community ◽  
Parasite Richness ◽  
Species Invasions ◽  
The Relationship

scholarly journals Rodent sociality and parasite diversity

2007 ◽  
Vol 3 (6) ◽  
pp. 692-694 ◽  
Author(s):  
Frédéric Bordes ◽  
Daniel T Blumstein ◽  
Serge Morand
Keyword(s):  
Species Richness ◽  
Group Size ◽  
Host Species ◽  
Independent Contrasts ◽  
Parasite Diversity ◽  
Social Species ◽  
Dilution Effects ◽  
The Relationship ◽  
Biotic Environment

The risk of parasitism is considered to be a general cost of sociality and individuals living in larger groups are typically considered to be more likely to be infected with parasites. However, contradictory results have been reported for the relationship between group size and infection by directly transmitted parasites. We used independent contrasts to examine the relationship between an index of sociality in rodents and the diversity of their macroparasites (helminths and arthropods such as fleas, ticks, suckling lice and mesostigmatid mites). We found that the species richness of directly transmitted ectoparasites, but not endoparasites, decreased significantly with the level of rodent sociality. A greater homogeneity in the biotic environment (i.e. a reduced number of cohabiting host species) of the more social species may have reduced ectoparasites' diversity by impairing ectoparasites transmission and exchange. Our finding may also result from beneficial outcomes of social living that include behavioural defences, like allogrooming, and the increased avoidance of parasites through dilution effects.

scholarly journals The epidemiological signature of pathogen populations that vary in the relationship between free-living survival and virulence

2020 ◽  
Author(s):  
Lourdes M. Gomez ◽  
Victor A Meszaros ◽  
Wendy C. Turner ◽  
C. Brandon Ogbunugafor
Keyword(s):  
Public Health ◽  
Disease Dynamics ◽  
Free Living ◽  
Evolutionary Changes ◽  
Evolution Of Virulence ◽  
Parasite Survival ◽  
Transmission Studies ◽  
Pathogen Populations ◽  
Host Parasite ◽  
The Relationship

ABSTRACTThe relationship between parasite virulence and transmission is a pillar of evolutionary theory that has specific implications for public health. Part of this canon involves the idea that virulence and free-living survival (a key component of transmission) may have different relationships in different host-parasite systems. Most examinations of the evolution of virulence-transmission relationships—theoretical or empirical in nature—tend to focus on the evolution of virulence, with transmission a secondary consideration. And even within transmission studies, the focus on free-living survival is a smaller subset, though recent studies have examined its importance in the ecology of infectious diseases. Few studies have examined the epidemic-scale consequences of variation in survival across different virulence-survival relationships. In this study, we utilize a mathematical model motivated by aspects of SARS-CoV-2 natural history to investigate how evolutionary changes in survival may influence several aspects of disease dynamics at the epidemiological scale. Across virulence-survival relationships (where these traits are positively or negatively correlated), we found that small changes (5% above and below the nominal value) in survival can have a meaningful effect on certain outbreak features, including the R0, and the size of the infectious peak in the population. These results highlight the importance of properly understanding the mechanistic relationship between virulence and parasite survival, as evolution of increased survival across different relationships with virulence will have considerably different epidemiological signatures.

scholarly journals Migratory behaviour predicts greater parasite diversity in ungulates

2018 ◽  
Vol 285 (1875) ◽  
pp. 20180089 ◽  
Author(s):  
Claire S. Teitelbaum ◽  
Shan Huang ◽  
Richard J. Hall ◽  
Sonia Altizer
Keyword(s):  
Infection Risk ◽  
Comparative Approach ◽  
Parasite Diversity ◽  
Long Distance ◽  
Parasite Communities ◽  
Parasite Richness ◽  
The Social ◽  
Single Host ◽  
Long Distance Movement ◽  
The Relationship

Long-distance animal movements can increase exposure to diverse parasites, but can also reduce infection risk through escape from contaminated habitats or culling of infected individuals. These mechanisms have been demonstrated within and between populations in single-host/single-parasite interactions, but how long-distance movement behaviours shape parasite diversity and prevalence across host taxa is largely unknown. Using a comparative approach, we analyse the parasite communities of 93 migratory, nomadic and resident ungulate species. We find that migrants have higher parasite species richness than residents or nomads, even after considering other factors known to influence parasite diversity, such as body size and host geographical range area. Further analyses support a novel ‘environmental tracking' hypothesis, whereby migration allows parasites to experience environments favourable to transmission year-round. In addition, the social aggregation and large group sizes that facilitate migration might increase infection risk for migrants. By contrast, we find little support for previously proposed hypotheses, including migratory escape and culling, in explaining the relationship between host movement and parasitism in mammals at this cross-species scale. Our findings, which support mechanistic links between long-distance movement and increased parasite richness at the species level, could help predict the effects of future environmental change on parasitism in migratory animals.

scholarly journals Parasite diversity and ecology in a model species, the guppy ( Poecilia reticulata ) in Trinidad

2020 ◽  
Vol 7 (1) ◽  
pp. 191112 ◽  
Author(s):  
Ryan S. Mohammed ◽  
Stanley D. King ◽  
Paul Bentzen ◽  
David Marcogliese ◽  
Cock van Oosterhout ◽  
...  
Keyword(s):  
Species Richness ◽  
Life History Traits ◽  
Poecilia Reticulata ◽  
Parasite Species ◽  
New Records ◽  
Survival Strategies ◽  
Snail Species ◽  
Parasite Diversity ◽  
Model Species ◽  
Parasite Richness

The guppy ( Poecilia reticulata ) is a model species in ecology and evolution. Many studies have examined effects of predators on guppy behaviour, reproduction, survival strategies, feeding and other life-history traits, but few have studied variation in their parasite diversity. We surveyed parasites of 18 Trinidadian populations of guppy, to provide insight on the geographical mosaic of parasite variability, which may act as a source of natural selection acting on guppies. We found 21 parasite species, including five new records for Trinidad. Spatial variation in parasite diversity was significantly higher than that of piscine predators, and significant variation in parasite richness among individuals and populations was correlated with: (i) host size, (ii) snail species richness, and (iii) the distance between populations. Differences in parasite species richness are likely to play an important, yet underestimated role in the biology of this model species of vertebrate ecology and evolution.

Richness and distribution of tropical oyster parasites in two oceans

Parasitology ◽  
2016 ◽  
Vol 143 (9) ◽  
pp. 1119-1132 ◽  
Author(s):  
KATRINA M. PAGENKOPP LOHAN ◽  
KRISTINA M. HILL-SPANIK ◽  
MARK E. TORCHIN ◽  
LEOPOLDINA AGUIRRE-MACEDO ◽  
ROBERT C. FLEISCHER ◽  
...  
Keyword(s):  
International Trade ◽  
Species Richness ◽  
Panama Canal ◽  
Perkinsus Marinus ◽  
Parasite Diversity ◽  
Molecular Screening ◽  
Bocas Del Toro ◽  
Marine Systems ◽  
Parasite Richness ◽  
Ecosystem Level

SUMMARYParasites can exert strong effects on population to ecosystem level processes, but data on parasites are limited for many global regions, especially tropical marine systems. Characterizing parasite diversity and distributions are the first steps towards understanding the potential impacts of parasites. The Panama Canal serves as an interesting location to examine tropical parasite diversity and distribution, as it is a conduit between two oceans and a hub for international trade. We examined metazoan and protistan parasites associated with ten oyster species collected from both Panamanian coasts, including the Panama Canal and Bocas del Toro. We found multiple metazoan taxa (pea crabs, Stylochus spp., Urastoma cyrinae). Our molecular screening for protistan parasites detected four species of Perkinsus (Perkinsus marinus, Perkinsus chesapeaki, Perkinsus olseni, Perkinsus beihaiensis) and several haplosporidians, including two genera (Minchinia, Haplosporidium). Species richness was higher for the protistan parasites than for the metazoans, with haplosporidian richness being higher than Perkinsus richness. Perkinsus species were the most frequently detected and most geographically widespread among parasite groups. Parasite richness and overlap differed between regions, locations and oyster hosts. These results have important implications for tropical parasite richness and the dispersal of parasites due to shipping associated with the Panama Canal.

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