To the classic case studies of evolution, such as Darwin’s finches and the peppered moth, a small group of researchers would now add the Mexican tetra. This small, freshwater fish is mostly found as a drably colored inhabitant of creeks and rivers. But at least a half dozen times, populations have taken up residence in caves, where they have been…
Only a few genetic changes are needed to spur the evolution of new species — even if the original populations are still in contact and exchanging genes. Once started, however, evolutionary divergence evolves rapidly, ultimately leading to fully genetically isolated species, report scientists from the University of Chicago in the Oct. 31 Cell Reports. “Speciation is one of the most…