Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Talia on 19/12/2010 19:49:13
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Hello!
What do you think about hybrids? Should we protect them?
And in cases if there is no "pure" populations anymore, should we protect hybrids or not?
Currently think of Cobitis hybrids.
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Talia:
A strict biological definition of species depends upon whether two separate populations are completely interfertile (they can interbreed and the young are fertile). Ones who are interfertile can be considered variants of the same species. Variants of a species (and new species) develop by being isolated from one another, or by adapting to different environmental factors within the territory of a widely distributed species. It isn't uncommon for variants of a species to interbreed naturally at a boundary between populations. A good example is the Mexican characin, Astyanax mexicanus. This species has two extreme variants, a cave form that has lost almost all pigmentation and has no outward evidence of eyes (there is a small degenerate vestigial cyst under the skin) while the river form is very visually active and pigmented. At a cave mouth the two forms interbreed naturally and they are interfertile.
So, I have obviously provided more information than anybody wants, but in light of this what specific situation are you concerned with? Is somebody breeding spiny loaches and releasing them?
Steve
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Thanks for your response!
So, I'm interested if there is no more pure generations (there are only its hybrids)... do we need to protect those hybrids?
For example, if these hybrids are located in isolated habitats or populations of these hybrids is low ... should they be declared as endangered species?
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In some sense all species are hybrids. If you are thinking of a naturally occurring population that bridges, or bridged in the past, variants of a species, then I would think that they should be protected. If the variants are gone, for some reason, hybrids would contain almost all of the genetic information of the originals, and this should be preserved. Natural and artificial breeding could actually recreate the original variants. It would help if you provided a specific example of what you are asking about. If your question is hypothetical, just make up an example.
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There would be many examples where a species has been completely eradicated. Then a close relative has been re-introduced.
For example native populations of wolves have been eradicated in many areas of the USA, then later reintroduced with close relatives. The same thing with the Grizzly Bear.
In the case of a re-introduced species, the introduced group should held in no greater esteem than the species as a whole.
The Zebra is interesting. There may be some local differences in coat coloration.
There is a subspecies named the Quagga that had no stripes on the rear. The current belief is that the Quagga was closely related to the Plains Zebra. So, there is now an effort to re-breed a group of zebras with coloration similar to the now extinct Quagga. Will it truly be the same? Perhaps it won't make a difference.
Equines are somewhat unique that Donkeys, Horses, & Zebras all have different numbers of chromosomes, and thus the offspring will have an odd number of chromosomes and is thus infertile.
http://en.wikipedia.org/wiki/Zebroid
Canines, however, are much more capable of interbreeding, but also run into chromosome differences between dogs, foxes, and certain jackals.
http://en.wikipedia.org/wiki/Canid_hybrid
Certainly an infertile hybrid should not be given any special consideration other than protection of its parent lines.
A fertile hybrid, such as those found in the dogs... I suppose it would just depend on the age of the subspecies, and if there is any cultural significance.
If I was to choose breed a Chihuahua and Saint Bernard it should not be given any special consideration other than being an oddity of nature.
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Steve and Clifford thank you very much! You have helped me a lot!
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Talia, you are welcome. Steve