Predictions of primate–parasite coextinction

2021 ◽  
Vol 376 (1837) ◽  
pp. 20200355 ◽  
Author(s):  
James P. Herrera ◽  
James Moody ◽  
Charles L. Nunn
Keyword(s):  
Infectious Disease ◽  
Network Structure ◽  
Interaction Network ◽  
Biodiversity Loss ◽  
Primate Species ◽  
Ecosystem Functions ◽  
Parasite Diversity ◽  
Theme Issue ◽  
Ecological Associations ◽  
Host Parasite

Future biodiversity loss threatens the integrity of complex ecological associations, including among hosts and parasites. Almost half of primate species are threatened with extinction, and the loss of threatened hosts could negatively impact parasite associations and ecosystem functions. If endangered hosts are highly connected in host–parasite networks, then future host extinctions will also drive parasite extinctions, destabilizing ecological networks. If threatened hosts are not highly connected, however, then network structure should not be greatly affected by the loss of threatened hosts. Networks with high connectance, modularity, nestedness and robustness are more resilient to perturbations such as the loss of interactions than sparse, nonmodular and non-nested networks. We analysed the interaction network involving 213 primates and 763 parasites and removed threatened primates (114 species) to simulate the effects of extinction. Our analyses revealed that connections to 23% of primate parasites (176 species) may be lost if threatened primates go extinct. In addition, measures of network structure were affected, but in varying ways because threatened hosts have fewer parasite interactions than non-threatened hosts. These results reveal that host extinctions will perturb the host–parasite network and potentially lead to secondary extinctions of parasites. The ecological consequences of these extinctions remain unclear. This article is part of the theme issue ‘Infectious disease macroecology: parasite diversity and dynamics across the globe’.

Drivers of parasite β-diversity among anuran hosts depend on scale, realm and parasite group

2021 ◽  
Vol 376 (1837) ◽  
pp. 20200367 ◽  
Author(s):  
Paulo Mateus Martins ◽  
Robert Poulin ◽  
Thiago Gonçalves-Souza
Keyword(s):  
Infectious Disease ◽  
Spatial Scale ◽  
Regional Scale ◽  
Global Scale ◽  
Spatial Distance ◽  
Parasite Diversity ◽  
Theme Issue ◽  
Diversity Patterns ◽  
Essential Step ◽  
Β Diversity

A robust understanding of what drives parasite β-diversity is an essential step towards explaining what limits pathogens' geographical spread. We used a novel global dataset (latitude −39.8 to 61.05 and longitude −117.84 to 151.49) on helminths of anurans to investigate how the relative roles of climate, host composition and spatial distance to parasite β-diversity vary with spatial scale (global, Nearctic and Neotropical), parasite group (nematodes and trematodes) and host taxonomic subset (family). We found that spatial distance is the most important driver of parasite β-diversity at the global scale. Additionally, we showed that the relative effects of climate concerning distance increase at the regional scale when compared with the global scale and that trematodes are generally more responsive to climate than nematodes. Unlike previous studies done at the regional scale, we did not find an effect of host composition on parasite β-diversity. Our study presents a new contribution to parasite macroecological theory, evidencing spatial and taxonomic contingencies of parasite β-diversity patterns, which are related to the zoogeographical realm and host taxonomic subset, respectively. This article is part of the theme issue ‘Infectious disease macroecology: parasite diversity and dynamics across the globe’.

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.

Towards a mechanistic understanding of competence: a missing link in diversity–disease research

Parasitology ◽  
2020 ◽  
Vol 147 (11) ◽  
pp. 1159-1170 ◽  
Author(s):  
Tara E. Stewart Merrill ◽  
Pieter T. J. Johnson
Keyword(s):  
Infectious Disease ◽  
Community Ecology ◽  
Dilution Effect ◽  
Biodiversity Loss ◽  
Current Evidence ◽  
Clear Understanding ◽  
Future Directions ◽  
Disease Research ◽  
Mechanistic Understanding

AbstractBiodiversity loss may increase the risk of infectious disease in a phenomenon known as the dilution effect. Circumstances that increase the likelihood of disease dilution are: (i) when hosts vary in their competence, and (ii) when communities disassemble predictably, such that the least competent hosts are the most likely to go extinct. Despite the central role of competence in diversity–disease theory, we lack a clear understanding of the factors underlying competence, as well as the drivers and extent of its variation. Our perspective piece encourages a mechanistic understanding of competence and a deeper consideration of its role in diversity–disease relationships. We outline current evidence, emerging questions and future directions regarding the basis of competence, its definition and measurement, the roots of its variation and its role in the community ecology of infectious disease.

scholarly journals A review of regulation ecosystem services and disservices from faunal populations and potential impacts of agriculturalisation on their provision, globally

2018 ◽  
Vol 30 ◽  
pp. 1-39 ◽  
Author(s):  
Claudia Gutierrez-Arellano ◽  
Mark Mulligan
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Service Provision ◽  
Service Use ◽  
Agricultural Land ◽  
Biodiversity Loss ◽  
Ecosystem Functions ◽  
Natural Ecosystem ◽  
Structure Degradation ◽  
Animal Populations

Land use and cover change (LUCC) is the main cause of natural ecosystem degradation and biodiversity loss and can cause a decrease in ecosystem service provision. Animal populations are providers of some key regulation services: pollination, pest and disease control and seed dispersal, the so-called faunal ecosystem services (FES). Here we aim to give an overview on the current and future status of regulation FES in response to change from original habitat to agricultural land globally. FES are much more tightly linked to wildlife populations and biodiversity than are most ecosystem services, whose determinants are largely climatic and related to vegetation structure. Degradation of ecosystems by land use change thus has much more potential to affect FES. In this scoping review, we summarise the main findings showing the importance of animal populations as FES providers and as a source of ecosystem disservices; underlying causes of agriculturalisation impacts on FES and the potential condition of FES under future LUCC in relation to the expected demand for FES globally. Overall, studies support a positive relationship between FES provision and animal species richness and abundance. Agriculturalisation has negative effects on FES providers due to landscape homogenisation, habitat fragmentation and loss, microclimatic changes and development of population imbalance, causing species and population losses of key fauna, reducing services whilst enhancing disservices. Since evidence suggests an increase in FES demand worldwide is required to support increased farming, it is imperative to improve the understanding of agriculturalisation on FES supply and distribution. Spatial conservation prioritisation must factor in faunal ecosystem functions as the most biodiversity-relevant of all ecosystem services and that which most closely links sites of service provision of conservation value with nearby sites of service use to provide ecosystem services of agricultural and economic value.

scholarly journals Linking sex differences to the evolution of infectious disease life-histories

2018 ◽  
Vol 373 (1757) ◽  
pp. 20170431 ◽  
Author(s):  
Matthew D. Hall ◽  
Nicole Mideo
Keyword(s):  
Infectious Disease ◽  
Sex Differences ◽  
Life Histories ◽  
Test Case ◽  
Theme Issue ◽  
Genetic Covariance ◽  
Covariance Functions ◽  
Genetic Constraint ◽  
Males And Females ◽  
Evolutionary Consequences

Sex differences in the prevalence, course and severity of infection are widespread, yet the evolutionary consequences of these differences remain unclear. Understanding how male–female differences affect the trajectory of infectious disease requires connecting the contrasting dynamics that pathogens might experience within each sex to the number of susceptible and infected individuals that are circulating in a population. In this study, we build on theory using genetic covariance functions to link the growth of a pathogen within a host to the evolution and spread of disease between individuals. Using the Daphnia–Pasteuria system as a test case, we show that on the basis of within-host dynamics alone, females seem to be more evolutionarily liable for the pathogen, with higher spore loads and greater divergence among pathogen genotypes as infection progresses. Between-host transmission, however, appears to offset the lower performance of a pathogen within a male host, making even subtle differences between the sexes evolutionarily relevant, as long as the selection generated by the between-host dynamics is sufficiently strong. Our model suggests that relatively simple differences in within-host processes occurring in males and females can lead to complex patterns of genetic constraint on pathogen evolution, particularly during an expanding epidemic. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences’.

scholarly journals Rigorous surveillance is necessary for high confidence in end-of-outbreak declarations for Ebola and other infectious diseases

2019 ◽  
Vol 374 (1776) ◽  
pp. 20180431 ◽  
Author(s):  
Robin N. Thompson ◽  
Oliver W. Morgan ◽  
Katri Jalava
Keyword(s):  
Infectious Disease ◽  
Disease Outbreaks ◽  
Decision Makers ◽  
World Health ◽  
Theme Issue ◽  
Public Health Decision ◽  
Infectious Disease Outbreaks ◽  
Travel Restrictions ◽  
Health Decision ◽  
Health Organization

The World Health Organization considers an Ebola outbreak to have ended once 42 days have passed since the last possible exposure to a confirmed case. Benefits of a quick end-of-outbreak declaration, such as reductions in trade/travel restrictions, must be balanced against the chance of flare-ups from undetected residual cases. We show how epidemiological modelling can be used to estimate the surveillance level required for decision-makers to be confident that an outbreak is over. Results from a simple model characterizing an Ebola outbreak suggest that a surveillance sensitivity (i.e. case reporting percentage) of 79% is necessary for 95% confidence that an outbreak is over after 42 days without symptomatic cases. With weaker surveillance, unrecognized transmission may still occur: if the surveillance sensitivity is only 40%, then 62 days must be waited for 95% certainty. By quantifying the certainty in end-of-outbreak declarations, public health decision-makers can plan and communicate more effectively.This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’. This issue is linked with the earlier theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.

scholarly journals Translating surveillance data into incidence estimates

2019 ◽  
Vol 374 (1776) ◽  
pp. 20180262 ◽  
Author(s):  
Y. Bourhis ◽  
T. Gottwald ◽  
F. van den Bosch
Keyword(s):  
Infectious Disease ◽  
Disease Incidence ◽  
Disease Outbreaks ◽  
Estimation Methods ◽  
Estimation Model ◽  
Theme Issue ◽  
Online Application ◽  
Infectious Disease Outbreaks ◽  
Sampling Series ◽  
Wide Range

Monitoring a population for a disease requires the hosts to be sampled and tested for the pathogen. This results in sampling series from which we may estimate the disease incidence, i.e. the proportion of hosts infected. Existing estimation methods assume that disease incidence does not change between monitoring rounds, resulting in an underestimation of the disease incidence. In this paper, we develop an incidence estimation model accounting for epidemic growth with monitoring rounds that sample varying incidence. We also show how to accommodate the asymptomatic period that is the characteristic of most diseases. For practical use, we produce an approximation of the model, which is subsequently shown to be accurate for relevant epidemic and sampling parameters. Both the approximation and the full model are applied to stochastic spatial simulations of epidemics. The results prove their consistency for a very wide range of situations. The estimation model is made available as an online application. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.

scholarly journals Adequacy of SEIR models when epidemics have spatial structure: Ebola in Sierra Leone

2019 ◽  
Vol 374 (1775) ◽  
pp. 20180282 ◽  
Author(s):  
Wayne M. Getz ◽  
Richard Salter ◽  
Whitney Mgbara
Keyword(s):  
Infectious Disease ◽  
Transmission Function ◽  
Disease Outbreaks ◽  
District Level ◽  
Transmission Model ◽  
Theme Issue ◽  
Infectious Disease Outbreaks ◽  
Country Level ◽  
Level Data ◽  
Populations At Risk

Dynamic SEIR (Susceptible, Exposed, Infectious, Removed) compartmental models provide a tool for predicting the size and duration of both unfettered and managed outbreaks—the latter in the context of interventions such as case detection, patient isolation, vaccination and treatment. The reliability of this tool depends on the validity of key assumptions that include homogeneity of individuals and spatio-temporal homogeneity. Although the SEIR compartmental framework can easily be extended to include demographic (e.g. age) and additional disease (e.g. healthcare workers) classes, dependence of transmission rates on time, and metapopulation structure, fitting such extended models is hampered by both a proliferation of free parameters and insufficient or inappropriate data. This raises the question of how effective a tool the basic SEIR framework may actually be. We go some way here to answering this question in the context of the 2014–2015 outbreak of Ebola in West Africa by comparing fits of an SEIR time-dependent transmission model to both country- and district-level weekly incidence data. Our novel approach in estimating the effective-size-of-the-populations-at-risk ( N eff ) and initial number of exposed individuals ( E 0 ) at both district and country levels, as well as the transmission function parameters, including a time-to-halving-the-force-of-infection ( t f/2 ) parameter, provides new insights into this Ebola outbreak. It reveals that the estimate R 0 ≈ 1.7 from country-level data appears to seriously underestimate R 0 ≈ 3.3 − 4.3 obtained from more spatially homogeneous district-level data. Country-level data also overestimate t f/2 ≈ 22 weeks, compared with 8–10 weeks from district-level data. Additionally, estimates for the duration of individual infectiousness is around two weeks from spatially inhomogeneous country-level data compared with 2.4–4.5 weeks from spatially more homogeneous district-level data, which estimates are rather high compared with most values reported in the literature. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’. This issue is linked with the subsequent theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’.

Assessing the diversity, host-specificity and infection patterns of apicomplexan parasites in reptiles from Oman, Arabia

Parasitology ◽  
2016 ◽  
Vol 143 (13) ◽  
pp. 1730-1747 ◽  
Author(s):  
JOÃO P. MAIA ◽  
D. JAMES HARRIS ◽  
SALVADOR CARRANZA ◽  
ELENA GOMÉZ-DÍAZ
Keyword(s):  
Phylogenetic Analysis ◽  
Host Specificity ◽  
Quantitative Pcr ◽  
Parasite Diversity ◽  
Phylogenetic Clustering ◽  
Apicomplexan Parasites ◽  
Host Ecology ◽  
Phylogenetic Framework ◽  
Host Parasite ◽  
Wild Hosts

SUMMARYUnderstanding the processes that shape parasite diversification, their distribution and abundance provides valuable information on the dynamics and evolution of disease. In this study, we assessed the diversity, distribution, host-specificity and infection patterns of apicomplexan parasites in amphibians and reptiles from Oman, Arabia. Using a quantitative PCR approach we detected three apicomplexan parasites (haemogregarines, lankesterellids and sarcocystids). A total of 13 haemogregarine haplotypes were identified, which fell into four main clades in a phylogenetic framework. Phylogenetic analysis of six new lankesterellid haplotypes revealed that these parasites were distinct from, but phylogenetically related to, knownLankesterellaspecies and might represent new taxa. The percentage of infected hosts (prevalence) and the number of haemogregarines in the blood (parasitaemia) varied significantly between gecko species. We also found significant differences in parasitaemia between haemogregarine parasite lineages (defined by phylogenetic clustering of haplotypes), suggesting differences in host–parasite compatibility between these lineages. ForPristurus rupestris, we found significant differences in haemogregarine prevalence between geographical areas. Our results suggest that host ecology and host relatedness may influence haemogregarine distributions and, more generally, highlight the importance of screening wild hosts from remote regions to provide new insights into parasite diversity.

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