How Did Flies Evolve?
WouterWhether flies have always been related or not is an interesting question. Scientists often use fruit flies as models for evolution and genetic research. They breed at a rate of 20 generations per year, and they have tiny wings, which makes it easy to measure minute changes. Houle and colleagues studied the DNA sequences of fruit flies, as well as fossils and other evidence to determine the relationship between flies and their ancestors.
It is thought that folding wings helped the prey to hide from flying predators and exploit niches that are difficult to access otherwise. Insects that folded their wings over their abdomens were a dominant group, as they could use those wings to protect themselves. This would allow them to move through different environments more easily.
During the last glacial period, insects were mainly terrestrial. However, they also had the ability to live in the crowns of trees. These insects would have had limited space to hide in, so it would have been hard for them to develop wings if they lived in the trees. As a result, many of the primitive fossil forms had numerous subimagos. Although subimagos in modern species don’t eat, the ancient insects likely fed during this stage of life. In some cases, it would take several moults before they reached the adult form.
The wings and legs of modern mayflies are similar to those of their ancestors, but they have distinct modifications. For example, mayflies don’t have gills until after their first moult. This means that they could be the common ancestors of all flyers. However, it is unlikely that early terrestrial insects had wings.
