at what point of evolution is a new species recognized?

Question

explanation to question: pigeons have lived for a while now, right!? they're, even now, in the process of evolving. so at what point do we name another species of pigeons? if there was SUDDENLY a mutated pigeon with rainbow colored feathers that came from a regular pigeon is that considered a new species?

thanks!

Answer 1

A population of organisms that will not, or cannot interbreed with another population and produce fertile offspring can be considered to be different species, no matter how closely the two species resemble each other. So if they will not interbreed, you can say for certain that they are separate species.



The problem is that there is a lot of historical baggage attached to the word, and in the past taxonomists classified similar looking animals into the same species, or different looking animals into different species because they had no other information. There is a slow revolution in this, since genomics are revealing that some species thought to be fairly closely related on the basis of appearance are considerably different, while some others of different appearance are in fact an interbreeding group. This will probably take 50 years or more to sort out, as taxonomy is not a field of science that has ever been terribly popular and is of course, underfunded.

Answer 2

A species is defined as follows:-



"A group of organisms which can only naturally interbreed within itself, the offspring of which are both viable and fertile"



What this means is that some species interbreed and but the offspring are infertile - therefore although they are closely-related they are still separate species (example: lion and tiger). Furthermore, "viable" means that although mating may take place between species, the offspring must be born - and born without deformity. "Naturally" means that although we can sometimes trick different species to successfully interbreed, they don't do so on their own (example: two particular species of European Grasshopper).



From this, it follows that a new species is recognised when a population becomes divided and each part stops interbreeding with the other for whatever reason. In the first instance, the cessation of interbreeding is usually the result of some behavioural change (in the example of the European Grasshoppers, it's just a change in frequency of their mating call) but later on as the two species continue to evolve separately physical and genetic barriers occur which means that the two species would never be able to interbreed.



An example of this separation into two species is being observed at the moment in Orca (Killer Whales) where some groups of Orca have been observed to only hunt fish and are noticeably smaller in size whilst other groups where the individuals are larger only hunt seals. The fish-hunting and whale-hunting groups do not interbreed as far as we have observed and are therefore in the process of becoming two separate species.



As with many things in nature, there is no one instant in time where they actually become two separate species - the concept of a species is a man-made invention which nature doesn't care about. So they will be two new species when someone writes a scientific paper calling for them to be recognised as such and the scientific community agree.

Answer 3

A change of plumage would not be considered evidence that a new species has evolved. A species is a type of organism that is adapted to a particular ecological niche, or way of life. Therefore a population is considered a new species if it has adapted to a new niche. The classic example of new species evolving can be found among the finches of the Galapagos Islands. These finches are adapted to different ways of life and that can be found in the shape of their bills. For example, there are finches with large short bills that allow them to crack nuts. There are also finches with long, thin bills that are adapted to feeding on nectar. There are a total of 13 species of Galapagos finches, also known as Darwin's finches. They have been found, using DNA and morphological evidence, to have evolved from a single species of finch that found its way to the islands.



Since individuals of the same species all occupy the same ecological niche, they are similar in what they eat, where they nest and so on. That also means they compete against one another. Because of such intense competition, many individuals will not be able to survive and may die because of starvation or other causes, such as the inability to find a nest site. If some of these starving birds were to try eating other foods, then they may find that they will be able to survive. If they keep eating the new kind of food, then they avoid competing with other individuals that still eat the old food. Since the food is new, these individuals may not have the right kind of bill to handle it, but since there is no other birds eating this new food, they are able to hang on. If and when there is a chance mutation that helps these birds eat the new food more efficiently, then the individuals with the mutation will have an advantage and they will survive better and reproduce better. After a series of such mutations, the birds that eat the new food may lose the advantage of these new mutations if they interbreed with the individuals that they had evolved from, because their descendants may have a bill that is intermediate between the old and new diets, and therefore they may not be able to handle either kinds of diet well.



At this point, if the two kinds of birds eating different foods can avoid interbreeding with one another, for example, if one of them evolves a new song, then the two kinds of birds are considered different species, since some of them have evolved to be so different that they can no longer interbreed with the old species without hurting the ability of their descendants to survive and reproduce. For example, if a finch with a nut-cracking bill were to interbreed with a finch with a long thin, nectar eating bill, then their young may have a bill that is neither strong enough to crack nuts nor long enough to eat nectar. If they do not refrain from interbreeding then they will produce young that has a reduced chance of survival. Natural selection will therefore weed them out, and that is why we often see different but closely related species behave themselves and refrain from interbreeding across species boundaries in nature, even if they live in the same area. When 2 populations live in the same area and they don't interbreed except on rare occasions, then these 2 populations have become different species.

Answer 4

If the rainbow pigeon mated with another rainbow pigeon and only had rainbow colored babies, and then, could no longer create offspring naturally with any other type of pigeon... Then it becomes a new species, no longer a "pigeon"

Answer 5

It's the sort of thing that one knows after the point they separate, not during.