Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Prevalence of Infection in a Population Can Shape Parasite Virulence and More: Press Release from PLoS Biology

19.07.2005


If necessity is the mother of invention, the coevolutionary arms race is the mother of adaptation. For parasites and hosts engaged in an ongoing battle to gain advantage, those adaptations take many forms. In a new analysis in the premier open access journal PLoS Biology, Stephanie Bedhomme, Yannis Michalakis, and colleagues extend traditional methods of studying the coevolution of parasite virulence and host life history traits by introducing an additional variable: intraspecific competition between hosts. Unsurprisingly, the authors find that infected individuals pay a cost compared to their healthy counterparts. But surprisingly, both infected and uninfected individuals do better when their competitor is infected: parasite costs –and virulence – therefore depend on the infection status of the competitors and for an infected mosquito, at least, you stand a better chance of getting your wings and leaving the natal lagoon if more of your larval neighbors are infected too.



To study the interplay between parasitism and intraspecific competition, Bedhomme et al. worked with the yellow fever mosquito Aedes aegypti and its natural enemy, the single-celled parasite Vavraia culicis. They divided recently hatched mosquito larvae into groups of 60 larvae, and exposed half of the groups to the parasite. Larvae were then placed two by two into vials. Vials contained either two uninfected larvae, two infected larvae, or one infected and one uninfected individual. Infected pairs took longer to develop than uninfected pairs, as expected. But with infected and uninfected pairs, infected larvae took longer to develop than their healthy partners, meaning they are more likely to succumb to the parasite. Competing against a healthy partner increased virulence by increasing development time. Interestingly, however, infected mosquitoes also fared better when paired with an infected competitor.

These results suggest that a high incidence, or prevalence, of parasitic infection in the population means that healthy larvae face less competition and do better than they would if they had to compete with healthy individuals. Infected individuals will also do better if there’s a high prevalence of infection because they are more likely to compete against equally poor competitors. Thus, by ignoring the effects of competition, standard models underestimate the full costs of virulence—and, more important, miss a significant link between a parasite’s prevalence in a population and its virulence.


Citation: Bedhomme S, Agnew P, Vital Y, Sidobre C, Michalakis Y (2005) Prevalence-dependent costs of parasite virulence. PLoS Biol 3(8): e262.

The published article will be accessible to your readers at: http://dx.doi.org/10.1371/journal.pbio.0030262

CONTACT:
Yannis Michalakis
IRD-CNRS
911 Avenue Agropolis
Montpellier, France 34394
+33-4-67-41-61-54
Yannis.Michalakis@mpl.ird.fr

****************************

Space Matters: Estimating Species Diversity in the Fossil Record

Estimates for the number of living species on earth range from 3.5 million to over 30 million but only 1.9 million species have been classified and described. Estimating historical biodiversity from the fossil record is an even more daunting task. One tool ecologists – but not paleontologists - have traditionally relied on to identify patterns of existing biological diversity is a long-established rule of thumb called the species–area effect: the tendency for species number, or richness, to increase in a predictable way with area. Paleontologists have been unable to account for the species–area effect, or to even know whether it applies, in estimating paleodiversity because of various confounding factors. But, in a new study, published in the premier open access journal PLoS Biology, Anthony Barnosky, Marc Carrasco, and Edward Davis are able to test this assumption and discover that the golden rule of ecology holds for the rock record as well. Just as geographic sampling influences diversity counts in the modern landscape, the species–area effect strongly influences counts in the fossil record. Taking this into account will alter historical estimates of species distributions and extinction.

Barnosky et al. used mapping and imaging systems that generate direct measures of the geography for a given set of fossil species. To get a sense of diversity across time and space, the authors used a recently completed archival database (which they also built) that integrates the geographic data with fossil datasets, called the Miocene Mammal Mapping Project (MIOMAP). MIOMAP includes all western North American mammals from 5–30 million years ago - 3,100 localities and 14,000 occurrences of species in all. The authors then tested the fossil data for species–area effects by plotting fossil species richness against different geographic areas. After correcting for possible biases in sample size that might influence the number of species, Barnosky et al. found a strong species–area effect.

These results, they argue, suggest that many fluctuations in diversity seen in fossil analyses actually arise from the species–area effect and are not actually the result of true changes in the distribution of species. Given the lack of uniform geographic sampling in paleontological data, the impact of this effect may be significant - and likely applies to other taxa as well. Once the effect is factored in, one might expect significant adjustments in accepted patterns of global and regional paleodiversity. And because an important metric for understanding current extinctions relies on descriptions of past extinction events, controlling for a paleodiversity–area effect may provide a better frame of reference for understanding the current biodiversity crisis. Thanks to the innovative text-mining tools and approach presented here, future studies can more easily correct for area effects and explore these issues. And given the parallels between species–area relationships in paleontology and ecology, collaborations across disciplines may offer valuable insights into ecological dynamics through time.

Citation: Barnosky AD, Carrasco MA, Davis EB (2005) The impact of the species–area relationship on estimates of paleodiversity. PLoS Biol 3(8): e266.

The published article will be accessible to your readers at: http://dx.doi.org/10.1371/journal.pbio.0030266

CONTACT:
Anthony D Barnosky
University of California, Berkeley
3060 Valley Life Sciences Building
Berkeley, CA USA 94720
+1-510-643-6275
+1-510-642-5318 (fax)
barnosky@berkeley.edu

Paul Ocampo | alfa
Further information:
http://www.plosbiology.org

More articles from Life Sciences:

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

nachricht Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Global threat to primates concerns us all

19.01.2017 | Ecology, The Environment and Conservation

Scientist from Kiel University coordinates Million Euros Project in Inflammation Research

19.01.2017 | Awards Funding

The Great Unknown: Risk-Taking Behavior in Adolescents

19.01.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>