The majority of adaptations that produce a species that is the fittest to survive take long periods of time. Researchers from Eawag and the University of Bern in Switzerland have discovered an example of evolution that only took 150 years to produce two different species of three-spined stickleback fish. The discovery was reported in the Feb. 29, 2016, edition of the journal Public Library of Science Genetics.
The original invasion of the stickleback into Lake Constance on the border between Germany and Switzerland was documented 150 years ago. The fish has no commercial value and is not considered to be a dangerous invasive species. The three-spined stickleback has mutated into two different genetic species in 150 years. The two different species predominately occupy the lake and the rivers that feed the lake.
Natural selection has been thought to demand that some drastic influence must occur to produce a new species. Difference in water temperature or a habitat at different depths is sufficient to spur the development of a new species. The researchers have found no definite cause for the Lake Constance stickleback to have become two species. The existence of two species was documented by genetic testing.
The two species breed in the same regions at the same times. This fact makes the development of two separate species even rarer. The two species should have mated with each other and produced one species but some unknown factor has caused two species to evolve from the original fish in a very short time frame in a small region.