Academic Advisory Board

Fruit flies (Drosophila melanogaster) are model research organisms and are frequently reared in research institutions. Research specimens domesticated in a laboratory-reared setting may have different behavioral phenotypes as compared to their wild counterpart. Additionally, it has been determined that the absence of “key” stimuli in the physical environment of captive animals may result in altered behavioral patterns1. The purpose of this investigation was to test for differences in the behavioral phenotype of outdoor captured fruit flies as compared to laboratory-reared fruit flies with the use of three tests: an Upward Movement Assay, a Starvation Assay, and a Phototaxic Assay. Results from the Upward Movement Assay demonstrated statistically significant differences in the vertical moving speed of laboratory-reared flies and outdoor-caught flies. Results from the Phototaxic Assay revealed outdoor captured fruit flies exhibited a natural phototaxic behavior while laboratory-reared flies exhibited an inverse phototaxic behavior. The Starvation Assay proved that flies recently descended from outdoor caught fruit flies were able to withstand starvation twice as long as laboratory-reared flies. These results indicate a strong behavioral difference between flies that are descended from laboratory stock and flies that are caught from the outdoors. Research regarding the differences in domesticated organisms is an imperative topic for study because domestication and genetic drift have the potential to alter the behavioral phenotype. Changes in the behavioral phenotype may jeopardize the results of research experiments. Thus it is crucial to have a thorough comprehension of the behavior of outdoor caught fruit flies as compared to the behavior of their wild counterpart. It is suggested scientists change their fruit fly stock every few hundred generations in an effort to protect the natural gene pools of organisms which are bred in captivity for extended periods of time. Introduction Domestication is the evolutionary genetic change arising from the transition of a population from nature to deliberate human cultivation2. Animals have been domesticated both unconsciously and methodically since the end of the Pleistocene Era. Due to cultivation and routine human interactions with species, selection pressures are created and the effected species is forced to adapt to a new environment. The transition of a free-living culture to captive status is often accompanied by changes in availability A Comparison of Laboratory-Reared Stock and Captured Fruit Flies (Drosophila melanogaster) using Upward Movement, Phototaxic, and Starvation Assays Reveals Significant Behavioral Differences Trinity Russell1* and Richard Kurtz2 Student1, Teacher2: Commack High School, 1 Scholar Lane, Commack, NY 11725 *Corresponding author: [email protected] IN SCHOOL ARTICLE and/or accessibility of shelter, space, food, water, predation, and the social environment1. It is implied that the phenotype of the domesticated species will differ from its counterpart once it has undergone domestication. As natural selection has the ability to change the frequency of traits within a population, it has been discovered that the brain of an organism has the tendency to shrink when bred in captivity for extended periods of time3. Two approaches have been developed to gain a better understanding of the domestication process: a comparison of wild and domestic stocks (of a species), and the study of wild and domestic hybrids4. This experiment utilized the first approach, a comparison of the wild and domestic stocks of a species, to understanding the domestication process. The wild stock (outdoor captured fruit flies) is used as a representative and ancestor of the domesticated population (laboratory-reared fruit flies). A comparative approach between specific populations of wild versus domesticated animals at a single point in time is applied to this study. This experiment and other similar research tests suggest altered behaviors are a result of altered genes. Specific alleles have a relatively large impact on the development of behavioral characteristics specific to domesticated animals. For example, a study was conducted to identify the genetic variation between cultivated rice and its wild progenitor. This study assessed the genetic basis of the changes associated with the process of rice domestication. A total of 19 traits related to domestication in cultivated rice were discovered5. Another study demonstrated that laboratory-reared flies and wild fruit flies exhibit differences in an ovipositor choice test6. In the choice tests, using white and black artificial ovipositor domes, the wild flies’ selected black domes almost exclusively, but the laboratory-reared flies failed to display any preference6. Additionally, a study compared the behavior of wild and domestic stocks of Brook Trout. Results proved the domesticated group was much more vulnerable to trap-netting than the wild groups. After a week of trapping fish, 84% of the captured fish were from the domesticated group7. Drosophila’s favorable characteristics make it an ideal research specimen. They require minimal care, space, and equipment. In addition, fruit flies are easily cultivated in the laboratory; they have a high fecundity, and a short generation time. Thus, they are highly susceptible to genetic drift and domestication. Drosophila is presently one of the most commonly used model organisms in biological research. They serve as a genetic model for numerous diseases. They are also used to study aging, oxidative stress, immunity, diabetes, cancer, obesity and drug abuse8. Laboratory-reared fruit flies are essential in biological research and it is crucial to have a thorough understanding of their