The Varsity takes a look at the latest research coming out of the University of Toronto. This week we examine fruit flies, genetics and natural selection.
Researchers
Professor Marla Sokolowski and doctoral student Mark Fitzpatrick.
Findings
The recently completed research shows that having the rare form of a gene can be beneficial in certain populations. This runs contrary to the normal expectations of natural selection, where only the fittest variant would survive and become the most abundant variant over time.
Method
Using fruit fly larvae, two variants of a gene that controls feeding behaviour were tested against each other. Larvae with the “rover” version of the gene tend to seek out food actively, whereas the larvae with the “sitter” version tend to be more stationary. The differing larval genotypes are physically identical and were identified through green fluorescent proteins that bind to a specific target protein and glow under UV light. The fitness of the larvae was measured by keeping track of how many lived to reach the end of the larval stage.
Variables
Colonies of flies were raised with different amounts of food and with differing ratios of rovers and sitters.
Results
In cases where only a few individuals had one form of the gene in a given environment, they fared better than their counterparts with the other form of the gene.
Implications
These results suggest a reason for the appearance of rare genetic variants in nature. Varying environmental conditions (food amounts) can favour different variants of a gene at different times. As this foraging gene is found in mice and humans, variations in this gene could potentially be linked to eating disorders.
Future Steps
The research team hopes to find evidence of this negative frequency dependent selection in the wild. This would help explain why individuals in most species differ from each other so greatly.
