Evolution of Learning Ability in Fruit Flies

Learning & Memory in Fruit Flies

Scientists have traditionally viewed learning and memory as "complex traits" in the sense that they are believed to be the net result of various different genetic and environmental factors interacting with one another. As it is not always practical or ethical to use human subjects in research, simpler "model" organisism are often used, and drosophila melanogaster (i.e. the fruit fly) is one of the most well known and well studied in the biological sciences.

Abstract

Two thousand fruit flies of the species Drosophilia melanogaster were maintained for six months before any experimenting began. Flies subjected to experimentation were 14 days old and were conditioned to be better learners.

Petri dishes filled with pineapple juice and orange juice were used on which the flies could lay their eggs. Quinine was added to one of the juices to turn flies away from that medium. By selecting eggs from the juice that did not contain quinine, flies who had learned to avoid the juice with quinine passed on their learning ability.

Subsequent generations of fruit flies did actually become "smarter" as demonstrated be their ability to more readily differentiate between the quinine medium and the regular medium as well as their ability to remember this association for a longer period of time.

Methods

Experimental Design

Base Population

All flies used in Mery & Kawecki's experiment were of the species Drosophilia melanogaster. The experimental population was derived from 2000 flies and maintained for six months before any experimenting began. All flies subjected to experimentation were 14 days old.

Experimental Evolution Design

Before any testing was actually con...

... middle of paper ...

... the different genetics of every individual fly, but in general, it is possible to say that it did improve. This proves the point that learning is favored when environmental factors and other cues play a significant role. The experiment also showed that the learning ability to modify oviposition substrate choice has direct correlations with fitness.

Single-locus large-effect mutants would be the best approach for this experiment, but the group wanted to simulate learning ability in a natural environment so they chose to use a variegated sample.

References

Mery, Frederic & Tadeusz J. Kawecki. "Experimental evolution of learning ability in fruit flies." Proc.Natl. Acad. Sci. 99.22 (2002): 14274-14279.

Papaj, Daniel R. and Emilie C. Snell-Rood. "Memory flies sooner from flies that learn faster." Proc. Natl. Acad. Sci. 104.34 (2007): 13539-13540.