Origin of Species
Darwin is credited with solving the question of where the species originated.
Mayr
- "Darwin never really did discuss the origin of species in his book 'The Origin of Species.'"
Not only could Darwin not site a single example of a new species originating, but neither
has anyone else in the 140 years since. Patterons - "No one has ever produced a species
by mechanisms of natural selection. No one has gotten near it ..."
Actually there are several examples of new species arising in the last few decades. Most of these are flowering plants which hybridised, that is to say two different but closely related plant species mixed their pollen, the result being a new plant which would not reproduce well with either parent, but unlike most hybrids, was fertile.
Locally (in Texas) the fire ant has evolved a new characteristic based on the local poison control. Fire ants in Texas are generally killed with a slow bait poison. As a result the fire ant mounds have evolved to contain multiple queen ants so the mound does not die when one queen is eliminated. In the deep south the original characteristic of one and only one queen is retained. Fire ants have only been in the U.S. for a bit more than 50 years.
In general as species change, they can still interbreed, and in doing so will mix the genes such that they do not become so different that they cannot breed. Once in a while some unusual changes can occur. These usually are in the chromosomes, the separate chains of DNA that make up the whole life picture for a creature. In general to mate, the animals must have the same number of chromosomes and they need to match up. There are cases where a chromosome can break in two parts. The creature can still mate, and the two parts will match up to the corresponding parts of a mate with an original unbroken chromosome.
There are also cases where two chromosomes can re-link. It is possible for the chromosomes to re-link in the opposite order from the original set. These creatures can also still mate with individuals with the two short (broken) chromosomes, but not with the original population. Over time these creatures will diverge greatly from the original population since all gene flow must go through the intermediate (short/broken) chromosome form of the population.
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