UCI’s Fruit Fly Society

UC Irvine researchers have discovered how fruit flies evolve over time by decoding the fly’s genome.

Their findings contradict previously established scientific beliefs that sexual organisms evolve in a similar way as more simple organisms.

In the Sept. 15 issue of Nature Magazine Online, the extensive study was published highlighting major breakthroughs including new evidence of evolution in more than 500 genes. These genes were linked to size, sexual maturation and life span of the Drosophila melanogaster, more commonly referred to as the fruit fly.

The findings indicate a gradual, widespread network of selective adaptation. This contradicts the long-held belief that sexual organisms evolve similarly to single-celled bacteria when a single genetic mutation sweeps through a population and becomes fixed on a particular part of the DNA.

“We conclude that, at least for life history characters such as development time, unconditionally advantageous alleles rarely arise, are associated with small net fitness gains or cannot fix because selection coefficients change over time,” reads the study.

The UCI research team decoded the specific genetic functions behind aging, development and fertility. The lead author and doctoral student, Molly Burke, compared genetically engineered “super flies” that reproduce and die much faster than normal flies, to a control group of normal fruit flies on a genome-wide basis. This was the first time that this type of study was done on a sexually reproducing organism.

Dr. Michael Rose, UCI professor of ecology and evolutionary biology who began breeding the group of “super flies” in 1991, noted that many drugs currently used to treat diseases such as diabetes and heart disease were developed based on those flawed beliefs. The potential for serious side effects in those drugs stems from developers focusing on a single gene instead of examining hundreds of possible gene groups as the new study shows.

According to the study, a fresh look at genetic adaptation can be explained in a number of ways.

“Providing a new perspective on the genetic basis of adaptation … the probability of fixation in wild populations should be even lower than its likelihood in these experiments. This suggests that selection does not readily expunge genetic variation in sexual populations, a finding which in turn should motivate efforts to discover why this is seemingly the case,” the study reads on Nature.com.

Additionally, the team found new information concerning common ancestors between unlikely entities. Previous studies had established a 70 percent gene match-up between mammals and the fruit fly, but the study shows a possibility of higher percentage similarities.

Kevin Thornton and Parvin Shahrestani of UCI and Joseph Dunham of the University of Southern California are co-authors of the study, which was funded by UCI and National Science Foundation grants.

Researchers and those involved with the study hope that their findings will lead to breakthroughs in genetic research for pharmaceuticals and other products.