Imperial College London Centenary
 
About Imperial
About ImperialContacts/getting hereAlumniResearchCoursesAbout this site
Select your text size  for this site here: Small Text Normal Text Large Text Extra Large Text

Note: Some of the graphical elements of this site are only visible to browsers that support accepted web standards. The content of this site is, however, accessible to any browser or Internet device.

 

Lack of sex could be a signpost to extinction, claim researchers


External Sites:
-PLoS Pathogens
(Imperial College is not responsible for the content of these external internet sites)

Under embargo for

15.00BST/20.00EDT
Thursday 27 October 2005

Researchers from Imperial College London believe that when species become asexual they could be on their way to extinction.

The research, published in PLoS Pathogens, looks at the genetic structure of Penicillium marneffei, an asexual fungus. The researchers found that although P. marneffei spores were able to spread over large distances on currents of air, they were not able to 'invade' the new environments in which they landed.

P. marneffei in culture

P. marneffei is a fungus which causes disease in people with damaged immune systems, such as HIV/AIDS patients, and it is only found in parts of south-east Asia.

Dr Mat Fisher Opens in new window, first author on the paper, from Imperial College London, says: "We believe the failure of P. marneffei to adapt to new environments is because the fungus has largely dispensed with sexual reproduction. Without sex, you will not have the mixing of genes it causes, something all organisms need in order to be able to adapt to new environments."

The researchers used DNA typing to show that different clones of the fungus are found in different environments, and believe that the adaptation of the fungus to these environments is limiting their ability to adapt to other areas. They believe this is why P. marneffei is only endemic to a relatively small area of south-east Asia.

Evolutionary theory predicts that while asexual organisms can initially prosper and outcompete their sexual cousins, they ultimately pay the price for being unable to adapt through the recombination of genes caused by sexual reproduction.

Even though the fungus makes spores which can spread over very large distances, the researchers found that all the samples from any given location were genetically very similar. This led them to the conclusion that the fungus becomes highly adapted to its local environment, making it highly successful there, but stopping it spreading to other areas.

Dr Bill Hanage Opens in new window, one of the paper's authors, from Imperial College London, adds: "By being asexual, P. marneffei is not only limiting its ability to adapt, it may be at risk of becoming extinct. If it is unable to adapt to new environments, it will be unable to adapt to changes in its current environment. While becoming asexual may provide short term advantages to a species, in the long term, they are likely to end up in evolutions ultimate dustbin extinction."

The study was funded by a Wellcome Trust Biodiversity Fellowship.

For further information please contact:

Tony Stephenson
Press Officer
Communications Division
Tel: +44 (0)20 7594 6712
Mobile: +44 (0)7753 739766
E-mail: at.stephenson@imperial.ac.uk

Notes to editors:

1. Low effective dispersal of asexual genotypes in heterogeneous landscapes by the endemic pathogen Penicillium marneffei, PLoS Pathogens.

2. Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based university whose reputation for excellence in teaching and research attracts students (11,000) and staff (6,000) of the highest international quality.
Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that enhance the quality of life and the environment - underpinned by a dynamic enterprise culture.
Website: www.imperial.ac.uk

[up]