Nature

No Sex Needed to Get Stronger

Asexual worms can even thrive on contaminated soils

By Stefan Anitei, Science Editor

15th of May 2007, 09:46 GMT

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Acrobeloides nanus' mouth under electronic microscope

The general concept is that sex is required to produce genetic variation, which is necessary in the evolution of the organisms. But some cope quite well, even in stressful conditions, without sex.

Soil contaminants were found to induce rapid genetic adaptations in the nematode worm Acrobeloides nanus. The worms from contaminated soil were found to have an even longer lifespan and lay more eggs than those from unpolluted soil, as proven by researcher Agnieszka Doroszuk.

Environmental pollution is a stress factor that influences the size, dynamics and structure of the natural populations, requiring genetic changes and adaptations.

The bacteria-eating nematode worm Acrobeloides nanus reproduces only asexually and it can be easily studied. This multidisciplinary approach, using ecology, toxicology, molecular biology and evolutionary biology methods, reveals the effect of soil pollution on various levels of biological

organization.

The worms were exposed to various pH and copper values. These two factors can have a synergistic effect on the nematode population. Under their action, unexpectedly quick adaptation and significant genetic changes occurred, rendering the worms in the polluted soil resistant to the contamination.

They even had more eggs and longer lifespan in contaminated soils than individuals of the same species from the clean soil. The quick adaptation of an asexual species challenges the general concept that asexual species change slower, being more vulnerable to stress than sexual species are.

Currently, these asexual species are used for testing in ecotoxicological risk evaluations, but this research questions their suitability for doing this. The results of this research could be used in protection strategies of natural populations, by focusing the environmental management more on biomass turnover rate and less on the structure and biomasss of various populations per se.

Doroszuk's thesis points out the fact that multidisciplinary approaches are essential to see the underlying mechanisms of the response to stress and their consequences in the natural systems.

TAGS:

worm | sex | contamination

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