New mathematical model explains how hosts survive parasite attacks

Mar 04, 2012
A parsnip webworm (Depressaria pastinacella) attacks the reproductive parts of wild parsnip (Pastinaca sativa). But the parsnip's defenses include a natural insecticide, which limits the capacity of the webworm to inflict damage. A new mathematical model demonstrates that multiple traits in host-parasite interactions give the host an evolutionary advantage that helps it survive. Credit: Christine Hanrahan

In nature, how do host species survive parasite attacks? This has not been well understood, until now. A new mathematical model shows that when a host and its parasite each have multiple traits governing their interaction, the host has a unique evolutionary advantage that helps it survive.

The results are important because they might help explain how humans as well as evolve to withstand parasite onslaught.

The research, reported in the March 4 online edition of Nature, was supported by the National Institute for Mathematical and (NIMBioS) and the National Science Foundation. The paper was co-authored by Tucker Gilman, a postdoctoral fellow at NIMBioS; Scott Nuismer, an associate professor of biology at the University of Idaho, and Tony Jhwueng, a past postdoctoral fellow at NIMBioS.

Evolutionary theory suggests that parasites and pathogens should evolve more rapidly than their hosts because they tend to have shorter generation times and often experience strong selection. But this creates a paradox: How can hosts, or "victim species," survive and even thrive despite continuous onslaught from more rapidly evolving parasitic enemies?

"In order to investigate the influence of the number of traits on , we used quantitative genetics and individual-based simulations to analyze a model of a victim-exploiter system," Gilman said. We were able to show that when multiple traits, not just a single trait, govern how the hosts and parasites interact, victims can gain the upper hand in the evolutionary arms race."

In nature, interactions between species are often influenced by multiple traits. For example, the resistance of wild parsnip to webworm attack depends on when the parsnip blooms and on concentrations of certain with insecticidal properties found in the plant. Similarly, teleost fish, such as tuna and halibut, have multiple defensive traits such as mucosal barriers and biocidal secretions that parasites must overcome in order to successfully infect the host.

"While the study focuses on host-parasite systems," Gilman said, "the results are general to any victim-exploiter pair. For example, in a predator-prey system, the predator has to first find, then capture, and finally subdue its victims, and a victim can deploy defensive traits at each stage of the attack."

Having multiple attack and defensive mechanisms may help prey species to evolve and maintain low interaction rates with their predators, according to the paper. In addition, the finding suggests that coevolution of multiple traits may help plants to limit the damage they receive from herbivores, and so may help to explain why the world is green.

Explore further: Deep sea fish eyesight similar to human vision

More information: Coevolution in multidimensional trait space favors escape from parasites and pathogens, Gilman RT, Nusimer SL, Dwueng D-C. Nature, 2012. dx.doi.org/10.1038/nature10853

Journal reference: Nature search and more info website

Provided by National Institute for Mathematical and Biological Synthesis

4.3 /5 (8 votes)

Related Stories

Do parasites evolve to exploit gender differences in hosts?

Feb 28, 2012

Some disease-causing parasites are known to favor one sex over the other in their host species, and such differences between the sexes have generally been attributed to differences in immune responses or behavior. But in ...

Predators and parasites may increase evolutionary stability

Oct 26, 2007

A new study explores the role of natural enemies, such as predators and parasites, for mixed mating, a reproductive strategy in which hermaphroditic plants and animals reproduce through both self- and cross-fertilization. ...

Plant Parasite 'Wiretaps' Host

Jul 30, 2008

A parasitic plant that sucks water and nutrients from its plant host also taps into its communications traffic, a new report finds. The research could lead to new ways to combat parasites that attack crop plants.

Recommended for you

Dogs hear our words and how we say them

Nov 26, 2014

When people hear another person talking to them, they respond not only to what is being said—those consonants and vowels strung together into words and sentences—but also to other features of that speech—the ...

Amazonian shrimps: An underwater world still unknown

Nov 26, 2014

A study reveals how little we know about the Amazonian diversity. Aiming to resolve a scientific debate about the validity of two species of freshwater shrimp described in the first half of the last century, ...

Factors that drive sexual traits

Nov 26, 2014

Many male animals have multiple displays and behaviours to attract females; and often the larger or greater the better.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.