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 a new article, published February 28 in the magazine section of the online, open-access journal PLoS Biology, David Duneau from Cornell University and Dieter Ebert from the University of Basel now propose that all sorts of characteristics that differ between the sexes of the host species can influence a parasite's adaptation.

These characteristics, such as morphology, physiology, behavior, diet and life history traits can, in fact, pose very different challenges and opportunities to the , and may result in the parasite adapting more to one host sex than the other. Sex-specific in parasites may also occur when parasites routinely encounter one host sex more frequently than another. Parasites that adapt to male or female hosts may help explain why we find differences in parasite prevalence and disease expression in the different sexes.

"Our ideas may help explain the widespread phenomenon of host sex-biased parasitism and disease expression," said Duneau. "We suggest a new perspective on host-parasite interactions, taking parasite evolution into account."

The paper outlines different scenarios in parasite evolution that might lead to sex-specific disease. These include 'sex-specific adaptations,' with subpopulations of the parasites having fixed but distinct adaptations to females or males; or 'single sex specialization,' where the parasite is specifically adapted to only one host sex; and finally 'plastic sex-specific disease expression,' where the parasite can vary its response depending on whether it finds itself in a male or female host.

However, there are very few documented examples of parasite adaptation to host sex and, to the authors' knowledge, there is no example of a host sex-specific . There are only a few examples of parasites being adapted to only one sex, such as a mite that infects only females of its —the bat Myotis daubentoni.

The authors argue that more research is now required to study how sex differences affect the evolution of parasites and the diseases they carry. Host sex is a key factor in studies in medicine and disease control, and if parasites adapt differently to the sexes then there is a strong argument, for example, that both sexes need to be included equally in clinical trials—currently an important concern in medicine.

In humans, there are well documented host-sex differences in parasite prevalence and infection symptoms, as well as prevention and treatment of infection. Further research in a range of organisms may reveal why the effects of vaccines can be sex-specific; how parasites are distributed among hosts and why parasites can be locally adapted to certain host .

Explore further: Study solves the bluetongue disease 'overwintering' mystery

More information: Duneau D, Ebert D (2012) Host Sexual Dimorphism and Parasite Adaptation. PLoS Biol 10(2): e1001271. doi:10.1371/journal.pbio.1001271

Related Stories

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.

Study finds role for parasites in evolution of sex

Jul 06, 2009

What's so great about sex? From an evolutionary perspective, the answer is not as obvious as one might think. An article published in the July issue of the American Naturalist suggests that sex may have evolved in part a ...

Recommended for you

Study solves the bluetongue disease 'overwintering' mystery

Sep 12, 2014

The bluetongue virus, which causes a serious disease that costs the cattle and sheep industries in the United States an estimated $125 million annually, manages to survive the winter by reproducing in the insect that transmits ...

Taking the 'sting' out of reproduction

Sep 12, 2014

(Phys.org) —Female parasitic wasps have more reproductive success when working together with other females, which can also explain sex biased reproduction, according to new research.

Golden retriever study sniffs for cancer clues

Sep 11, 2014

(HealthDay)—Michael Court is a scientist and a dog lover, so he jumped at the chance to enroll his golden retriever in a nationwide study aimed at fighting cancer and other ills in canines.

User comments : 0