Evolution is a process that occurs at a rapid pace and although it can be difficult to keep up with, new genetic analysis techniques make it possible to detect the earliest stages of species formation in order to better grasp the processes that drive speciation.
In order to understand these processes, a team of researchers from Switzerland's University of Bern analyzed the rapid speciation that occurs in three-spined stickleback in and around the area of Lake Constance. The results revealed that species can diverge very rapidly, even when the two daughter species are breeding alongside each other at the same time, contradicting the common necessity for reproductive isolation during speciation.
Unlike many other species, three-spined stickleback possess no commercial value and thus have not been affected by lake eutrophication, bank stabilization and channelization, allowing them to spread throughout the Swiss Central Plateau for the last 150 years.
The new genetic study reveals the secret to this species success: rapid adaptation to new habitats. In fact, this adaptation is so rapid that evolutionary biologists are now using them as a model for the divergence of one species into two or more distinct species.
The team discovered two different forms of the stickleback - one common in the lake and the other in inflowing streams - despite the fact that lake stickleback migrate into the streams during spawning seasons.
"It was completely unexpected for the species to diverge over such a short period, given that the sticklebacks breed at the same time and at the same sites," said David Marques, first author of the study.
Typically, independent species come into existence through adaptation to different habitats and reproductive isolation. Now, different breeding and spawning seasons can be added to that list.
The rapid evolution of a new variant alongside its original variant allows scientists to witness evolution in real time and may help scientists better understand how other species have diverged into two or more variants.
Although previous research has evidenced evolution in real time, the organisms examined were bacteria with short reproductive times, allowing the researchers to witness the process over thousands of generations.
The findings were published in the Feb. 29 issue of PLOS Genetics.
