In biology, a ring species is a connected series of neighboring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two “end” populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each “linked” species. Such non-breeding, though genetically connected, “end” populations may co-exist in the same region thus closing a “ring”.
First, in the ring species, there are no Darwin’s “struggle for existence” or physical barriers such as mountains, valleys, rivers in the ring species. There were many ring species, but they are denied by late scientific finding. Herring gull or seagull was a famous ring species until 16 years ago.
Molecular biology has been an important tool in studying biological evolution. One of major principle is further two groups or species, more different in their DNA sequences. In terms of herring gull, a paper by a Dutch biology in 2004 change erroneous belief.
If herring gull were a so-called ring species, there should have more differences between the animals in different regions than ones in the same region. However, finding from molecular biology study shows there should have more differences within animals in same regions than ones in different regions. The author’s conclusion is “The herring gull complex is not a ring species.” (Liebers 2004).
Like attracts like. Animals have tendency to meet and mate with ones with similar habit, color, diet, language, which is a biological nature. If animals are adjacent each other, they would have more similar colors, diets, languages and habits, and farther they are away, more dissimilar they are with those characters. Those factors affect willing and possibility of mating among them. Russians and Brazilians speak different languages; it is more difficult for Russians mating with Brazilians than Russians mating Russians and Brazilians with Brazilians. By ring species theory, Russians and Brazilians should be considered different species, and become different species.
Ring species is another case the mainstream Neo-Darwinians misinterpreted phenomenon to fit their theory. If a group of animals are in adjacent regions, they are closer and easier to meet and mate; this is jus a common sense.
Factors to determine species is not whether they like to mate, but their ability to give birth to ones who must have reproductive ability if they have chance to mate. Mules are muting products between horses and donkeys, but they can not reproduce among themselves, so mule is not a species.
When ones interpret a natural phenomenon, they usually do it with a personal bias, or based on their own beliefs. If ones agree to a theory true, they can find out all kinds of so-called scientific evidence to prove their petty theory true. There are many cases in history to tell this kind story.
A ring species is nothing else, but belongs to one species spanning a long range, so animals in both ends do not recognize each other.
Irwin, D. E. (2000). “Song variation in an avian ring species.” Evolution 54(3): 998-1010.
Irwin, D. E., J. H. Irwin, et al. (2001). “Ring species as bridges between microevolution and speciation.” Genetica 112-113: 223-243.
Liebers, D., P. de Knijff, et al. (2004). “The herring gull complex is not a ring species.” Proc Biol Sci 271(1542): 893-901.