The article's title is a lite. It should have been titled "No Fruit fly speciation even after 600 generations." Speciation is not the same as evolution. Evolution is simply heritable change. There have been many documented cases of heritable change in fruit flies and other animals. For example, there are wingless fruit flies for sale to those who need them to feed their young frogs. A wingless fruit fly is a change from the normal fruit fly, and this change can be inherited. These changes are in fact created by experiments. Facts therefore refute the claim that evolutionary biology is not an experimental science and therefore evolutionary theory is a myth or religious belief, not science.
Other kinds of evolutionary changes can be seen in other domestic animals, such as hairlesness in domestic dogs and pigs. They can also be seen in plants. Wild corn for example are very different from cultivated corn and these changes are heritable. Heritable change is different from non-heritable change such as tattoos. One can get a tattoo but one's child will not be born with a tattoo. OTOH, blond hair and blue eyes are changes to the genes that make some humans look different, and these differences are genetic and they can be passed along to future generations. Because these changes do not change one species into another, scientists call them microevolution. They also have a different term that describes changes that turn one species into another. They call it macro-evolution.
Macroevolution in nature may take thousands of years or longer, and they are not predictable. Most often they happen because there is a change in the environment. Normally a species may exist for millions of years and have hundreds of thousands of generations without changing much. In fact most changes would be deleterious if the environment does not change. OTOH, if the environment changes, some of the mutations that happen may by chance be advantageous instead of deleterious. These changes would then be incorporated into a species' genome. If the environment changes drastically enough, then the sum total of these changes may turn one species into a new one. But since these changes happen over a course of hundreds or even thousands of years in nature, no human being can observe these changes since humans live much shorter lives. To give an example. It takes for example 10 minutes to boil a pot of water. If we humans only live a total of 5 seconds, will we ever see a pot of water boil? If we must see something before we believe it, then we will claim that water never boils, which is of course false. Besides, how many creationists have ever seen god create anything living or non-living. Yet they do not demand any supporting evidence for their believes. Yet they demand eye witness evidence to show that one species actually evolve into another species within the lifetime of a single human being. That is simply unreasonable and they are also practicing double standards.
The last time humans evolved from one species to another was about 150,000-200,000 years ago. That means even if someone or something saw what happened back then, he/she/it cannot live long enough to tell us what he/she/it saw. Humans have not changed into a new species for close to 10,000 generations and we may not change for another 10,000 generations. That makes the fact that fruit flies have not become a new species after a mere 600 generations trivial. Our ancestor, Homo erectus, lived for 1.8 million years without changing into a new species. That is close to 100,000 generations without change. That puts into perspective the insignificant fact that fruit flies have not changed into a new species after 600 generations.