Can the formation of a new species be observed?
Two concepts of species We can now consider evidence for the evolution of new species. Most of the evidence so far has been for small-scale change within a species: house sparrows from all over North America are still classified as house sparrows, the same species as was introduced in the 1850s. The amounts of artificially selected change in pigeons and other domestic animals borders on the species level, but to decide whether the species barrier has been crossed we need a concept of what a biological species is. What does it mean to say a new species has evolved? The question lacks a simple answer that would satisfy all biologists. We can take two of the most important species concepts and see for each what the evidence for the evolution of a new species is. • One important species concept is reproductive, and defines a species as a set of organisms that interbreed among themselves but do not breed with members of other species. Humans (Homo sapiens ) are a separate reproductive speci
