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Posted by Eric on January 30, 2002 at 16:48:48:
In Reply to: Intergrades, Hybrids and morphs... posted by Royston Hunte on January 21, 2002 at 12:04:08:
: Does anyone know of any sources, "hard science" which clearly defines what hybrids, intergrades and morphs are? and or any sources for arguments as to the ethics of producing intergrades, hybrids and morphs? and or arguments, thesis documents etc which argue for or against the production of intergrades, hybrids and morphs? Thanks Royston
Great Question! Glad you asked. I'll start with some definitions from the Dictionary of ecology, evolution and systematics, Cambridge University Press.
Hybrid: Offspring of a cross between genetically dissimilar individuals; in taxonomy, often restricted to the offspring in interspecific (between different species) crosses.
Intergrade: an individual occurring on the boundry between adjacent subspecies and which possesses intermediate characters or traits.
Morph: A form; any of the individuals of a polymorphic group; any phenotypic or genetic variant; any local population of a polymorphic species exhibiting distinctive morphology or behaviour.
As for your second question, caprive bred animals should in general never be released into the wild. So most accademics have not concern for such things. They are outside of the natural world that they study.
If they are never going to be released then why not hybridize? Well for one thing, organisms that are members of a species are so because they have evolved seperately from other species and probably have adaptations which have evolved together. When organisms are hybridized they may have intermediate phenotypes that make little to no sense. There are common examples of these wierd behaviors in most intro biology books.
If your goal is to have animals that represent what occurs in the wild then hybridization can be a major problem. Most hybrids do not occur naturally.
I find intergrades to be less of a problem. Mainly because subspecies are not real units. The rank is artificial. If what we currently call species are found to be real evolutionary units then they are called species. Then crossing them would be hybridization not intergradation.
The problem is that we are not sure about the taxonomic status of most species in North America much less anywhere else in the world. The best bet is to keep good records of where an animal is from then as taxonomy catches up, you will know what you have and what you should breed it with.
Also don't knowingly hybridize animals. The results often look cool, but the animal will have no real natural history and you never know what complications may result.
This is of course my opinion. Other people are free to disagree, but be prepared to back up you arguments with logic if you do.
P.S. I am a herpetologist and a systematists.