Biologists predict extinction for organisms with poor quality genes

April 16, 2012
A genetic study by evolutionary biologists using fruit flies (Drosophila melanogaster) has shown that organisms with low-quality genes may produce offspring with even more inferior chromosomes, possibly leading to the extinction of certain species over generations. Credit: Nathaniel Sharp

Evolutionary biologists at the University of Toronto have found that individuals with low-quality genes may produce offspring with even more inferior chromosomes, possibly leading to the extinction of certain species over generations.

A study published in (PNAS) predicts that organisms with such genetic deficiencies could experience an increased number of in their DNA, relative to individuals with high-quality genes. The research was done on fruit flies whose simple system replicates aspects of biology in more , so the findings could have implications for humans.

"Mutations play a key role in cancer and other health problems affecting humans and other species," says Nathaniel Sharp, PhD candidate in U of T's Department of Ecology & Evolutionary Biology (EEB) and lead author of the study. "Our research suggests that the problem is likely to compound over time, leading to a mutational meltdown that may devastate endangered populations, and increase the risk of health problems in families in poor condition."

Sharp and EEB professor Aneil Agrawal examined the accumulation of mutations in the fruit fly Drosophila melanogaster, the genes of which are arranged on three major . To manipulate genetic quality, they introduced harmful mutations onto the fly's third chromosome. They then observed how the presence of these mutations affected the fitness of the second chromosome over 46 generations.

"Copies of chromosome two maintained in strains with poor-quality copies of chromosome three declined in fitness two to three times faster than those with good copies of chromosome three, suggesting that poor genetic quality elevates the mutation rate," says Sharp. While the underlying mechanism remains unknown, it could be tied to how an affected individual is less capable of repairing DNA or is more susceptible to DNA damage.

are especially useful for genetic studies such as this for the ability to screen for thousands of genes in thousands of flies much faster than in mammals. Flies are inexpensive to care for and reproduce rapidly, allowing for several generations to be studied in just a few months.

The researchers do, however, offer a more positive possible result of the process. "An elevated mutation rate under conditions of genetic or environmental stress could also accelerate adaptation to new environments," says Sharp.

Explore further: Study: Junk DNA is critically important

More information: The findings are reported in the paper "Evidence for elevated mutation rates in low-quality genotypes".

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3 comments

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mosahlah
1 / 5 (1) Apr 16, 2012
I imagine benevolent and socialist western societies propagates poor genes at a higher rate than the most productive of our species. I should expect the same fate would apply to our culture. Mandarin lessons anyone?
Old Badger
2.3 / 5 (3) Apr 16, 2012
Now let me get this straight.....genetic mutation is the fundamental requirement for natural selection to take place....pity it leads to rapid extinction!!
klawy
1 / 5 (1) Apr 16, 2012
Isin't this NS a little bit reformulated or am I missing something? Good genes and you will probably survive, bad you will probably die - haven't we comprehended that yet?

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