Featured Research

from universities, journals, and other organizations

Male Susceptibility To Disease May Play Role In Evolution Of Insect Societies

Date:
May 24, 2004
Source:
University Of Washington
Summary:
A pair of scientists has proposed a new model for behavioral development among social insects, suggesting that a higher male susceptibility to disease has helped shape the evolution of the insects' behavior.

A pair of scientists has proposed a new model for behavioral development among social insects, suggesting that a higher male susceptibility to disease has helped shape the evolution of the insects' behavior.

What might be called the "sick-male" theory has been proposed by animal behaviorists Sean O'Donnell of the University of Washington and Samuel Beshers of the University of Illinois at Urbana-Champaign, and appears in the current issue of Proceedings Biological Sciences, published by the Royal Society of London.

Among behaviors possibly affected are the division of labor between males and females and the relative social isolation experienced by males in many social insect colonies.

The researchers looked at Hymenoptera, an order of insects, including bees, ants and wasps, some of which have highly complicated societies and an unusual genetic makeup. These insects are called haplodiploids because males and females have a different number of sets of chromosomes. The females, like most animals, including humans, are diploid and have two sets of chromosomes, one from each parent. Hymenopteran males, however, hatch from unfertilized eggs and are haploids with just one set of chromosomes.

"Disease and infections are a very powerful and ongoing force in natural selection, and natural selection should favor individuals that possess forms of genes, or alleles, that make them more resistant to infection," said O'Donnell, a UW associate professor of psychology. "In some cases, an individual that has more than one form of a gene can ward off more parasites. In humans, for example, there are different forms of a blood gene that can help ward off malaria parasites. People with two different alleles for this gene are more resistant to malaria."

Because they are haploid, Hymenopteran males can't have alternate forms of any genes, or in other words, individual males have no genetic variability. This, O'Donnell and Beshers contend, puts males at a higher susceptibility to disease.

The researchers, who are trying to understand the basis of social behavior in these creatures, suggest that this male vulnerability has shaped certain behaviors in social insect colonies. These behaviors, they say, are designed to minimize the risk of disease transmission in a colony.

Division of labor is a prime example. While colonies vary widely in the total number of individuals, females vastly outnumber males and seem to do most of the work.

"Males typically do not do very much work for their colonies," said O'Donnell. "In some instances males do small amounts of labor inside the nest. But they rarely are allowed outside of the nest and they do not forage for food or building materials, activities that might expose them to disease pathogens.

"If males were exposed to disease we would expect females to avoid, and possibly to attack and kill those males to minimize disease being brought into the colony."

The sick-male theory proposes that female-biased societies, and differences in male and female behavior, may be responses to higher risks of infection to males, he said. The theory also predicts that in some cases males may be segregated or shunned inside the nest, again to reduce the colony's potential exposure to disease.

O'Donnell said much research still needs to be done to support the sick-male model and test whether males are less resistant to disease than females.

"We hope our study will inspire scientists to these ideas. Researchers need to challenge different species of social insects with disease pathogens to see whether males and females differ in disease resistance," he said. "Our understanding of the genetic basis of disease resistance is pretty weak, even medically. There actually is little evidence to show how genetic variability at the individual level is effective in fighting off disease, even though this is often assumed to be the case by biologists." The National Science Foundation funded the research.


Story Source:

The above story is based on materials provided by University Of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University Of Washington. "Male Susceptibility To Disease May Play Role In Evolution Of Insect Societies." ScienceDaily. ScienceDaily, 24 May 2004. <www.sciencedaily.com/releases/2004/05/040524055955.htm>.
University Of Washington. (2004, May 24). Male Susceptibility To Disease May Play Role In Evolution Of Insect Societies. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2004/05/040524055955.htm
University Of Washington. "Male Susceptibility To Disease May Play Role In Evolution Of Insect Societies." ScienceDaily. www.sciencedaily.com/releases/2004/05/040524055955.htm (accessed April 17, 2014).

Share This



More Plants & Animals News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Thousands Of Vials Of SARS Virus Go Missing

Thousands Of Vials Of SARS Virus Go Missing

Newsy (Apr. 16, 2014) A research institute in Paris somehow misplaced more than 2,000 vials of the deadly SARS virus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins